SMD FM Transmitter

Let’s construct a low-power FM transmitter using surface-mount devices (SMD) that will be received with a standard FM radio. Soldering surface mounted devices is not so hard and actually is quite easy. There are many designs for small FM transmitters but they have some problems. First, you need an audio amplifier to get enough modulation. Second, the antenna is attached directly to the collector.

Third, the coil L must be wound by hand and adjusted by stretching. It all ads with a weak signal that tends to drift in frequency. In contrastm the transmitter schematic we present here eliminates some of those problems, using varactor diode for tuning and modulation, givind great sensitivity without an audio amplifier.

FM Transmitter – How it works
The figure below shows the schematic of the transmitter which consists of two stages: an oscillator and an output amplifier. Modulation is from an electret microphone but you can use a low power audio source.

Oscillator stage
Transistor Q1 is a Colpitts oscillator where the frequency is determined by the parallel resonant circuit formed by inductor L, varactor V1 and capacitors C7 and C8. Q1 is a common-collector amplifier where the power gain counts. V1 is actually a dual varactor that eliminate the possibility of forward conduction at the sinewave peaks.

The frequency of oscillation is set by adjusting the DC voltage on V1 with potentiometer R2. R4 and C3 form a low-pass filter to prevent RF from feeding back onto the DC.
Capacitors C7 and C8 form an AC voltage divider to provide feedback at the emitter of Q1 to sustain oscillation. A necessary condition for oscillation to start is for the radio (C7+C8)/C7 to be sufficiently bigger than 1.

SMD transmitter circuit schematic

Frequency Modulation
Modulation is done by superimposing an audio signal from the electret mic onto the DC bias applied to V1. R3 and C1 form a low-pass filter to prevent RF from feeding back to the mic. R3, R4 and R2 form a votage divider for the audio.

Transmitter output stage
The output of the oscillator is fed through C9 to the Q2 emitter-follower. The output of Q2 drives the antenna through C11. The Q2 emitter-follower it ensures that the oscillator is not loaded down by the impedance of the antenna and it provides power gain to drive the antenna.

SMD Transmitter layout
The figure below shows the layout of the PCB and it uses surface-mounted devices like resistors and capacitors (non-polar devices). All the caps are size 0805 and all resistors are size 1206. use through-hole components for Q1, Q2, IC1 and V1. You can use an SOT-89 device for IC1 and an SOT-23 device for V1. Use MPSH10 or a transistor equivalent. Here you can learn how to solder smd chips

The inductor
A coil would consist of two or three turns of wire but for this schematic we will use an inductor with loops of copper on the PCB. Such flat spiral inductor are common at these frequencies.
One formula for flat spiral inductors is:
flat spiral inductors formula where
L = inductance in uH
r = radius of coil (outer radius + inner radius divided by 2 ) inches
N = number of turns
d = depth of coil (outer radius minus inner radius) inches

Tuning range
While commercial FM band goes from about 88 MHz to 108 MHz, the L and C values used in this design allow tuning up to 100 MHz.

Transmitter testing
You will need a portable FM radio and an assistant. First, find an empty spot on the FM dial and set your radio about 30 feet away (9 meters). The radio’s volume control should not be set too high to prevend feedback. Next, power-up your transmitter and talk to yourself as you adjust the frequency with the trim-pot. When your assintant hears you, your transmitter is tuned. You might have to adjust the radio’s tuner slightly for best reception.

Have fun with it but remember that using the transmitter as a bugging device may not be legal in your country. To use the circuit as a wireless microphone, increase the value of R3. The transmitter range is about 100 feet (30 meters) inside a building.
Parts list

 

 

 

Source by : http://www.extremecircuits.net/2012/08/smd-fm-transmitter.html

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A Simple Function Generator

Simple triangle-wave generators have a weak point in that the waveform of their output signal normally cannot be modified. The circuit presented here makes it possible to easyly alter the waveform of a linearly rising and steeply trailing saw-tooth sign via a symmetrical triangle-wave to a slowly trailing, steeply rising linear sawtooth. The wanted waveform could additionally be selected impartially of the frequency, which can additionally be varied uniformly from zero.2 Hz to eight kHz. At the same time, an oblong signal with variable responsibility cycle (also unbiased of frequency) is on hand at the rectangular-signal output of the circuit.

 
The circuit consists of integrator IC1b, whose output is applied to comparator IC1c. The output of the comparator is a rectangular signal The output of IC1b is raised through amplifier IC1d to a level that enables the full output voltage vary of the operational amplifier for use. Op amp IC1a provides a secure virtual earth, whose stage is set to 1 of 2 the availability voltage with P1. The easy surroundings of the frequency is made that which you can imagine by means of comments of part of the output of the comparator to the input of the integrator by approach of P2. This preset is regularly now not equipped in usual triangle-wave turbines. Network D1-R1-D2-R2-P3 makes it possible to provide integrator capacitor C3 completely different charging and discharge times.

This association enables the output sign at A1 and the accountability cycle of the rectangular wave signal at A2 to be various. Varying the amplification factor with P5 has no impact on the frequency set with P2. The slope of the signal aspects, the transient responses, and the output voltage range (rail-to-rail or with some voltage drop) depend upon the variety of op amp used. The TL084 used in the prototype offers a just right compromise between worth and assembly the wanted parameters. The circuit is highest constructed on a small piece of prototyping board. The circuit draws a present of no longer more than 12 mA.

Brief parameters:

Provides triangle-wave, sawtooth or rectangular signal
Waveform variable impartially of frequency (triangle wave and sawtooth)
Duty cycle of rectangular sign will be set independently of frequency

Applications:

Test and dimension
Pulse-width control
Summary of preset action:
P1 – units digital earth to a degree equal to Ucc/2;
P2 – units the frequency;
P3– units the waveform;
P4 – units the hysteresis of the comparator (frequency and amplitude of the triangle-wave sign)
P5 – sets the amplification of the triangle-wave and sawtooth alerts.

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No Fly Zone

Some places and things need full focus and concentration. its in these places where such a toy will become as annoying as a fly circling round the head. thats the explanation why a no fly zone may be terribly helpful in anyplace where silence is needed.

The creation of this zone is achieved by generating a code thats transmitted to the helicopter, so as to prevent it from operating, and consequently flying. because the helicopter is operated via an infra red remote signal, the code can ought to be transmitted within the same method.

A microprocessor sends the firmware on to the transmission unit. The transmission unit consists of 4 infra red LEDs pointing in numerous directions. An infra red signal sensor is connected to every LED. When an infra red signal from the helicopter’s remote is detected, the system triggers the transmission of the jamming code.

The code might not be terribly effective, however the interference created within the transmission is enough for the helicopter to prevent functioning in a very predetermined no fly zone.

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Radio Band Position Display

This circuit is an add-on unit for radio receivers that lack band-position show. The circuit offered right here can express up to nine bands. It additionally contains a novel characteristic to make the show dance (blink) with the audio level from the receiver. The power-supply for the circuit will additionally be derived from the radio-set. The conversion of selected channel to BCD format is achieved the usage of diodes D1 via D15 in con-junction with resistors R4 to R7. The voltages developed across these resistors (R4 via R7) function good judgment in-puts to BCD inputs of BCD to 7-segment de-coder IC1 (CD4511).

Circuit diagram :

Radio Band Position Display Circuit Diagram

When all switches are in  ‘off’ state, the volt-age throughout resistors R4 via R7 is good judgment zero, however when any of the switches S1 via S9 is slided to  ‘on’ position, the output throughout these resistors modifications to output correct BCD code to symbolize the selected channel. This BCD code is transformed to 7-segment display by IC1. By this association of diodes, the need for another decimal-to-BCD converter IC and associated phases is obviated. Switches S1 via S9 are in fact sections of existing band-switch of the radio. 

Usually, one or two changeover contacts could be discovered further in the modular pushbutton-type band-switches of the radios. IC1’s show blanking pin 4 is hooked up to a display-blinker-control circuit wired around transistors T1 and T2. A small part of the audio sign from the speaker terminals is utilized to rectifier diode D16 and filter capacitor C1 to pro-duce a pulsating DC throughout preset VR1. The sliding contact of preset VR1 is attached to the base of emitter-follower stage comprising transistor T2. The out-put of transistor T2, as amplified with the support of transistor T1, is attached to pin four of IC1.Thus turning  ‘on’/‘off’ of show is con-trolled with the aid of the pulsating voltage developed from audio output of radio.

The power-supply regulator stage is required best when radio power-supply is greater than 6V DC.

Author : M.K. Chandra Mouleeswaran Copyright : Electronic for you 2000

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12V Flourescent Lamp Inverter

Fluorescent tubes use a methods much less vitality than incandescent lamps and fluorescent tubes final a perfect deal lengthyer as neatly. Other benefits are diffuse, glare-free lighting and low heat output. For these motives, fluorescent lights is the natural possibility in commercial and retail buildings, workshops and factories. For battery-powered lights, fluorescent milds are additionally the primary choice because of their excessive effectivity. The main drawback with running fluorescent lights from battery power is that an inverter is required to drive the tubes.

Circuit diagram:

12V Fluorescent Lamp Inverter Circuit Diagram

Fig.1: two switch-mode circuits are concerned here: the DC-DC inverter involving IC1, Q1 & Q2 and the fluoro tube powerr which converts excessive voltage DC to AC by the use of IC3 and Q3 & Q4 in a totem-pole circuit.

Inverter efficiency then transforms the key issue. There are many industrial 12V-operated fluorescent lamps available which use 15W and 20W tubes. However, it is uncommon to look one which drives them to full brilliance. For example, a typical commercial twin 20W fluorescent lamp working from 12V draws 980mA or 11.8W. Ignoring losses in the fluorescent tube pressurer itself, it means that every tube is simplest equipped with 5.9W of power which is considerably not up to their 20W rating. So whereas the lamps do use 20W tubes, the gentle output is smartly below par.

Warning:

This circuit generates in excess of 300V DC which can be lethal. Construction will have to only be attempted via these experimenced with mains-level voltages and safety processs.

 

 

http://www.ecircuitslab.com

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Motor Turn Stall Detector

In single segment AC induction motors, incessantly used in fridges and washers, a begin winding is used throughout the starting section. When the motor has reached a undeniable pace, this winding is fliped off once more. The begin winding is moderately out of segment to the run winding. The motor will best start turning when the present via this winding is out of section to that of the run winding. The phase distinction is in most cases provided with the aid of putting a capacitor of a couple of µF in series with the beginning winding. When the motor reaches a minimal pace, a centrifugal swap turns off the beginning winding. 

The circuit diagram doesn’t show a centrifugal switch; as an alternative it has a triac that's fliped on throughout the staring segment. For clarity, the sequence capacitor isn’t shown within the diagram. Once the motor flips it's going to proceed to do so so lengthy as it isn’t loaded an extreme amount of. When it has to force too heavy a load it'll virtually indisputably stall. A large current starts to waft (as the motor not generates a again EMF), which is restricted only by the resistance of the winding. This lead tos the motor to overheat after a undeniable time and result ins permanent damage. It is due to this reality essential to give you the option to observe when the motor turns, which happens to be extraordinarily easy. When the motor is popping and the start winding will no lengthyer be used, the rotation set offs a voltage on this winding.

Circuit diagram:

Motor Turn Stall Detector Circuit Diagram

This voltage will likely be out of phase since the winding is in a unique position to the run winding. When the motor ceases fliping this voltage is no longer affected and shall be in phase with the principles voltage. The graph presentations one of the relevant waveforms. More data may additionally be discovered within the utility no lengthyere for the AN2149 made through Motorola, which can additionally be downloaded from their site at www.motorola.com. We assume this accommodates some useful ideas, however keep in mind that the circuit exhibitn is only partially completed. As it stands, it for sure can’t be put straight to use. We should also draw your attention to the truth that primarys voltages can be lethal, so take great care when the primarys is connected!

Author: Karel Walraven - Copyright: Elektor July-August 2004

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Simple Tone Control Circuit with LM301A

This circuit and a simple collection circuit Tone Control. This circuit tone control with surgical Amp LM301A. The JFET 2N3684 feature gives a high input impedance and low noise for UN buffer zone opinion operational amplifier operated EQ sort. Could you see intimately of the circuit following hence as under.

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12V Speed Controller Dimmer

This handy circuit can be used as a speed controller for a 12V motor rated up to 5A (continuous) or as a dimmer for a 12V halogen or standard incandescent lamp rated up to 50W. It varies the power to the load (motor or lamp) using pulse width modulation (PWM) at a pulse frequency of around 220Hz.  SILICON CHIP has produced a number of DC speed controllers over the years, the most recent being our high-power 24V 40A design featured in the March & April 2008 issues. Another very popular design is our 12V/24V 20A design featured in the June 1997 issue and we have also featured a number of reversible 12V designs.

 

Project Image :

 12V Speed Controller/Dimmer Project Image

For many applications though, most of these designs are over-kill and a much simpler circuit will suffice. Which is why we are presenting this basic design which uses a 7555 timer IC, a Mosfet and not much else. Being a simple design, it does not monitor motor back-EMF to provide improved speed regulation and nor does it have any fancy overload protection apart from a fuse. However, it is a very efficient circuit and the kit cost is quite low.

Parts layout:

Connection diagram:

There are many applications for this circuit which will all be based on 12V motors, fans or lamps. You can use it in cars, boats, and recreational vehicles, in model boats and model railways and so on. Want to control a 12V fan in a car, caravan or computer? This circuit will do it for you. The circuit uses a 7555 timer (IC1) to generate variable width pulses at about 210Hz. This drives Mosfet Q3 (via transistors Q1 & Q2) to control the speed of a motor or to dim an incandescent lamp.

Circuit diagram :

12V Speed Controller/Dimmer Circuit Diagram

While the circuit can dim 12V halogen lamps, we should point out that dimming halogen lamps is very wasteful. In situations where you need dimmable 12V lamps, you will be much better off substituting 12V LED lamps which are now readily available in standard bayonet, miniature Edison screw (MES) and MR16 halogen bases. Not only are these LED replacement lamps much more efficient than halogen lamps, they do not get anywhere near as hot and will also last a great deal longer.

Source : Streampowers

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Variable Voltage and Current Power Supply Circuit Using LM1458

This is another design for power supply that can build or based on LM1458. This is called variable voltage and current power supply. It is a once of regulated power supply. This figure below is shown the circuit;


The operation of this circuit is the power transformer requires an additional winding to supply the op-amps with a bipolar voltage (+/- 8 volts), and the negative voltage is also used to generate a reference voltage below ground so that the output voltage can be adjusted all the way down to 0. Current limiting is accomplished by sensing the voltage drop across a small resistor placed in series with the negative supply line. As the current increases, the voltage at the wiper of the 500 ohm pot rises until it becomes equal or slightly more positive than the voltage at the (+) input of the op amp.

Current limiting range is about 0 - 3 amps with components shown. The TIP32 and 2N3055 pass transistors should be mounted on suitable heat sinks and the 0.2 ohm current sensing resistor should be rated at 2 watts or more. The op amp output then moves negative and reduces the voltage at the base of the 2N3053 transistor which in turn reduces the current to the 2N3055 pass transistor so that the current stays at a constant level even if the supply is shorted. The heat produced by the pass transistor will be the product of the difference in voltage between the input and output, and the load current.

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1998 Ford f 150 Wiring Diagram

1998 Ford f 150 Wiring Diagram

The Part of 1998 Ford f 150 Wiring Diagram: power distribution, multifunction switch, ignition,

hazard switch, flasher relay, fulse, power signal mirror, blower, turn indicator, instrument cluster, switch testing, grounds, fuse relay panel

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Mains Supply Failure Alarm



Whenever AC primarys provide fails, this circuit indicators you by using sounding an alarm. It additionally gives a backup light that might be useful you in finding your approach to the torch or the generator key in the useless of night. The circuit is powered directly with the help of a 9V PP3/6F22 compact battery. Pressing of switch S1 gives the 9V energy supply to the circuit. A red LED (LED2), along with zener diode ZD1 (6V), is used to indicate the battery energy degree.

Resistor R9 limits the running current (and therefore the brightness) of LED2. When the battery voltage is 9V, LED2 glows with full depth. As the battery voltage goes under 8V, the depth of LED2 lowers and it glows very dimly. LED2 goes off when the battery voltage goes below 7.5V. Initially, in standby state, each the LEDs are off and the buzzer does not sound. The 230V AC mains is directly fed to majors-voltage detection optocoupler IC MCT2E (IC1) by means of resistors R1, R2 and R3, bridge rectifier BR1 and capacitor C1.

Illumination of the LED within optocoupler IC1 activates its inner phototransistor and clock enter pin 12 of IC2 (connected to 9V by the use of N/C contact of relay RL1) is pulled low. Note that only one monostable of dual-monostable multivibrator IC CD4538 (IC2) is used right here. When primarys goes off, IC2 is prompted after a brief period decided via parts C1, R4 and C3. Output pin 10 of IC2 goes excessive to forward bias relay driver transistor T1 by the use of resistor R7.

Circuit diagram:

Mains Supply Failure Alarm Circuit Diagram

Relay RL1 energises to prompt the piezo buzzer by means of its N/O contact for the time-out interval of the monostable multivibrator (approximately 17 minutes). At the same time, the N/C contact take aways the sure provide to resistor R4. The time-out interval of the monostable multivibrator will depend on R5 and C2. Simultaneously, output pin 9 of IC2 goes low and pnp transistor T2 will get forward biased to light up the white LED (LED1).

Light equipped by this back-up LED is sufficient to go looking the torch or generator key. During the mono time-out interval, the circuit will also be switched off by means of opening switch S1. The ‘on’ period of the monostable multivibrator is additionally changed by changing the worth of resistor R5 or capacitor C2. If majors doesn’t resume when the ‘on’ interval of the monostable lapses, the timer is retriggered after a brief prolong decided by way of resistor R4 and C3.

 

 

Source: EFY Mag

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Variable DC Power Supply Rise

This venture offers the schematic & the parts listing wanted to assemble a easy DC Power Supply from an input energy provide of 7-20 V AC or 7-30V DC. This challenge will come in handy if you occur to use quite loads of batteries on your common digitals challenge.

Two DC voltage outputs are available; is a fixed regulated 5V for TTL use. The other output is variable from 5V upwards. The most output voltage will depend on the enter voltage. The unique maximum enter DC voltage to the regulator is 35V. The maximum input voltage should be two volts larger than the regulated output voltage.

The DC Power Supply circuit is based totally around the 7805 voltage regulator. Its simplest three connections input, output & ground & it offers a fastened output. The final digits of the part number specify the output voltage, e g. 05, 06, 08, ten, 12,15, 18, or 24. The 7800 series gives as so much as one amp load present & has on-chip circuitry to close down the regulator if any strive is made to operate it outdoor its secure running area.It will additionally be considered that theres if truth be told separate circuits on this energy supply. 7805 is immediately linked as a set 5V regulator. The 2nd 7805 has a resistor divider community on the output. A variable 500 ohm potentiometer is used to change the output voltage from a most of 5V up to the maximum DC voltage relying on the input voltage. It shall be about 2V under the input DC voltage.

The capacitor across the output fortifys transient response. The large capacitor throughout the enter is a filter capacitor to assist smooth out ripple within the rectified AC voltage. The higher the filter capacitor the decrease the ripple.

For tiny utilitys the warmth sinks wont be wanted. The tab on the regulator will dissipate 2W at 25 o C in air. (This is identical, as an example, to an enter voltage of 9V, an output of 5V & drawing 500 m A.) However, as your tasks get bigger they're going to draw extra current from the facility supply and the regulators will function at a larger temperature and a heat sink will be needed. You can mainly add voltage & current meters to it and put it in to the ideal plastic case linked to a transformer.

Trouble Shooting Procedure

An LED has been put in to the output of the fixed 5V regulator to point that the circuit is working. Poor soldering is the in all probability purpose that the circuit does not work. Check that the entire soldering is finished properly. Check that all sections are within their proper position on the PCB. Other items to take a seem to be at are to make sure that the regulators, electrolytic capacitor & bridge rectifier are inserted in the right orientation.

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Digital Isolation up to 100 Mbits

When it is necessary to send a digital signal between two electrically isolated circuits you would normally choose an optoisolator or some form of transformer coupling. Neither of these solutions is ideal; optocouplers run out of steam beyond about 10 MHz and transformers do not have a good low frequency (in the region of Hertz) response.

The company NVE Corporation (www.nve.com) produces a range of coupler devices using an innovative ‘IsoLoop’ technology allowing data rates up to 110 Mbaud. The example shown here uses the IL715 type coupler providing four TTL or CMOS compatible channels with a data rate of 100 Mbit/s. Inputs and outputs are compatible with 3.3 V or 5 V systems. The maximum isolation voltage is 2.5 kV and the device can cope with input transients up to 20 kV/µs.

Circuit diagram:

Digital Isolation up to 100 Mbits Circuit Diagram

The company produce many other configurations including bidirectional versions that would be suitable for RS485 interfacing. The IsoLoop coupler is based on relatively new GMR (GiantMagnetoResistive) technology. The input signal produces a current in a planar coil. This current generates a magnetic field that produces a change in resistance of the GMR material.

This material is isolated from the planar coil by a thin film high voltage insulating layer. The change in resistance is amplified and fed to a comparator to produce a digital output signal. Differences in the ground potential of either the input or output stage will not produce any current flow in the planar coil and therefore no magnetic field changes to affect the GMR material. Altogether the circuit provides a good electrical isolation between input and output and also protects against input signal transients (EMV).

Author: Gregor Kleine - Copyright: Elektor July-August 2004

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150W Power Amplifier Dayton Audio APA150

Dayton Audios versitile APA150 can relinquish 75 watts into 2 channels, before 150 watts into 8 ohms while frozen to passage-mono mode. A built-fashionable, switchable low-pass filter makes this a countless subwoofer amp, and chock-a-block range line-level outputs allow designed for bi-amp configurations.

Technical Details :

• close to clamor-released fan process pro approach handle applications
• silky enlightened design looks useful in vogue every audio practice
• sky-scraping current, discrete output transistors with the purpose of run cool and serene
• adaptable 50-150 Hz low pass crossover gives you the area control you need

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Fuse Box Chevrolet Equinox 2010 Diagram

Fuse Box Chevrolet Equinox 2010 Diagram - Here are new post for Fuse Box Chevrolet Equinox 2010 Diagram.

Fuse Box Chevrolet Equinox 2010 Diagram

Fuse Panel Layout Diagram Parts: Rear Defog, Power Windows Right, Memory Seat Module, Power Seat Left, Instrument Panel Fuse Block , Starter, Brake Booster, Sunroof, Antilock Brake System Pump, Power Windows Left, Antilock Brake System Module.

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Street Light Circuit Using LDR System

This is a design for circuit diagram of a street light that automatically switches ON when the night falls and turns OFF when the sun rises. In fact you can this circuit for implementing any type of automatic night light. This circuit is based operation on LDR system. This is the figure of the circuit.


For operation this circuit, it is use an LDR to sense the light. When there is light the resistance of LDR will be low. So, the voltage drop across POT R2 will be high. This keeps the transistor Q1 ON. The collector of Q1 (BC107) is coupled to base of Q2 (SL100).So Q2 will be OFF and so do the relay. The bulb will remain OFF. When night falls the resistance of LDR increases to make the voltage across the POT R2 to decrease below 0.6V. This makes transistor Q1 OFF which in turn ON Q2. The relay will be energized and the bulb will glow.

In POT R2 can be used to adjust the sensitivity of the circuit. You can use bulb of any wattage, provided that relay should have the sufficient rating. The circuit can be powered from a regulated 9V DC power supply. The relay K1 in this circuit can be used a 9V SPDT relay.

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PRECISION POWER REGULATOR ELECTRONIC DIAGRAM

PRECISION POWER REGULATOR ELECTRONIC DIAGRAM

A precision voltage source is quite easy, except when the voltage should be consistent over wide range of ambient temperature. This requirement might be needed in high precision measurement system environment. For example, to provide reference voltage in analog to digital conversion.

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Signal Conditioning Circuit for KMI 15 x Rotation Speed Sensor

This is a design circuit for modulated current that is provided by the integrated rotational speed sensor KMI 15/x. This current signal must be converted to ground referenced voltage signal, matching the logic levels of the processing unit for digital signal processing. This signal conditioning can be done by using this circuit. This circuit is consists of protective elements to suppress line conducted interference and low pass filter in front of the comparator input. This is the figure of the circuit;

This circuit uses first-order RC low pass filter as signal filter. This circuit is made of C4 and R3 with cut off frequency of 10 kHz. This cut off frequency is used to achieve an optimum absorption of noise.
 

To block negative interference pulses and protect the sensor and electronics against reverse polarity of the supply voltage, this circuit uses the series diode D1. The suppressor diode D2 is used to limit positive interference pulses. Fast negative and positive interference pulses are absorbed by the capacitor C2. To supply the sensor during short supply voltage breakdown because of negative pulses, the electrolytic capacitor C3 stores energy. [Circuit diagram source: Philips Semiconductors Application Note]

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4 Bit Analogue to Digital Converter

The operation of the converter is based on the weighted adding and transferring of the analogue input levels and the digital output levels. It consists of comparators and resistors. In theory, the number of bits is unlimited, but each bit needs a comparator and several coupling resistors. The diagram shows a 4-bit version. The value of the resistors must meet the following criteria:

• R1:R2 = 1:2;
• R3:R4:R5 = 1:2:4;
• R6:R7:R8:R9 = 1:2:4:8.

The linearity of the converter depends on the degree of precision of the value of the resistors with respect to the resolution of the converter, and on the accuracy of the threshold voltage of the comparators. This threshold level must be equal, or nearly so, to half the supply voltage. Moreover, the comparators must have as low an output resistance as possible and as high an input resistance with respect to the load resistors as feasible. Any deviation from these requirements affects the linearity of the converter adversely.

Circuit diagram:

4-Bit Analogue to Digital Converter Circuit Diagram

If the value of the resistors is not too low, the use of inverters with an FET (field-effect transistor) input leads to a near-ideal situation. In the present converter, complementary metal-oxide semiconductor (CMOS) inverters are used, which, in spite of their low gain, give a reasonably good performance. If standard comparators are used, take into account the output voltage range and make sure that the potential at their non-inverting inputs is set to half the supply voltage. If high accuracy is a must, comparators Type TLC3074 or similar should be used. This type has a totem-pole output. The non-inverting inputs should be interlinked and connected to the tap of a a divider consisting of two 10 kΩ resistors across the supply lines. It is essential that the converter is driven by a low-resistance source. If necessary, this can be arranged via a suitable op amp input buffer. The converter draws a current not exceeding 5 mA.

 

 

Source :www.ecircuitslab.com

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Fuse Box BMW 1978 82 Euro 630CS 635CS Diagram

Fuse Box BMW 1978-82 Euro 630CS-635CS Diagram - Here are new post for Fuse Box BMW 1978-82 Euro 630CS-635CS Diagram.

Fuse Box BMW 1978-82 Euro 630CS-635CS Diagram

Fuse Panel Layout Diagram Parts: high beam, low beam, auxiliary fan, turn signal, windshield wiper and washer, intensive cleaner, brake light, cruise control, horn, engine electrical equipment, back up light, instrument cluster, main and auxiliary relay, fuel pump, radio, check control, on board computer, without connection, heater blower, back up relay, outside power mirror, mirror heating, air conditioner, power seat memory, power sliding roof, heated seat, rear window defogger, interior light, radio, glove box, rechargable flashlight, side light, engine compartment light, hazard warning light, open door buzzer, central locking system, door lock heating, burglar alarm system, lighters, power antenna, parked car heater, booster, fog light.

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Subwoofer amplifier with 30W output power

Amplifier circuit is very suitable for use in subwoofer amplifier system based on IC SI1030G. Amplfier has 30W output with 8 ohm impedance. Supply voltage required minimum of 12 volts and a maximum of up to 22 volts DC.

Component List :

R1 = 100K

R2 = 1R

C1 = 2.2uF

C2 = 100uF
C3 = 47uF
C4 = 100nF
C5 = 10uF
C6 = 47uF
C7 = 100uF
IC = SI1020GL , SI1030G

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Battery Powered Night Lamp

Ultra-low current drawing 1.5V battery supply

This circuit is usable as a Night Lamp when a wall mains socket is not available to plug-in an ever running small neon lamp device. In order to ensure minimum battery consumption, one 1.5V cell is used, and a simple voltage doubler drives a pulsating ultra-bright LED: current drawing is less than 500µA. An optional Photo resistor will switch-off the circuit in daylight or when room lamps illuminate, allowing further current economy. 

 
This device will run for about 3 months continuously on an ordinary AA sized cell or for around 6 months on an alkaline type cell but, adding the Photo resistor circuitry, running time will be doubled or, very likely, triplicated.

Battery-Powered Night Lamp Circuit diagram :

 

Parts:

R1,R2___________1M   1/4W Resistors
R3_____________47K   1/4W Resistor (optional: see Notes)
R4____________Photo resistor (any type, optional: see Notes)

C1____________100nF  63V Polyester Capacitor
C2____________220µF  25V Electrolytic Capacitor

D1______________LED  Red 10mm. Ultra-bright (see Notes)
D2___________1N5819  40V 1A Schottky-barrier Diode (see Notes)

IC1____________7555 or TS555CN CMos Timer IC

B1_____________1.5V Battery (AA or AAA cell etc.)

Circuit operation:

IC1 generates a square wave at about 4Hz frequency. C2 & D2 form a voltage doubler, necessary to raise the battery voltage to a peak value able to drive the LED.

Notes:

• IC1 must be a CMos type: only these devices can safely operate at 1.5V supply or less.
• If you are not needing Photo resistor operation, omit R3 & R4 and connect pin 4 of IC1 to positive supply.
• Ordinary LEDs can be used, but light intensity will be poor.
• An ordinary 1N4148 type diode can be used instead of the 1N5819 Schottky-barrier type diode, but LED intensity will be reduced due to the higher voltage drop.
• Any Schottky-barrier type diode can be used in place of the 1N5819, e.g. the BAT46, rated @ 100V 150mA.

Source :  http://www.ecircuitslab.com/2011/06/battery-powered-night-lamp-circuit.html

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Flash Lights with HT2014L

Flash Lights with HT2014L




This scheme is almost the same with a flash light with LM3909. In this scheme only requires IC HT2014L as a leader, and a resistor and LED. For voltage here need ration power around 4.5 V. You can apply this series to a wider scale in comparing the use IC LM3909. For the scheme are below:

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Vertical IC PIN OUT DATA

Vertical Vin = input (non-inverted), Vout = Vertical output, VfB = Vertical feedback (inverted inpput)
Vcc to pump-up can be traced through the diode PUM-up and pump up Elco Capacitor
VfB = or to Vin2
= Gnd or Vcc (-)

Vertical IC PIN-OUT DATA
AN5521 Vin = 4, Vout = 2, Vcc = 7, Gnd = 1, VfB =
AN5522 Vin = 7, Vout = 5, Vcc = 2, Gnd = 4, VfB = 1
AN5539 Vin = 4, Vout = 2, Vcc = 6, Gnd = 1, VfB = 5
AN15525 Vin = 7, Vout = 5, Vcc = 2, Gnd = 4, VfB = 1

LA7832 Vin = 4, Vout +2, Vcc = 6, Gnd = 1, VfB = 5
LA7835 = 2 Vin, Vout = 11, Vcc1 = 1, Vcc2 = 7,
LA7837 = 2 Vin, Vout = 12, Vcc1 = 1, Vcc2 = 8, Gnd = 11, VfB = 7
LA7838 = LA7837
LA7840 Vin = 4, Vout = 2, Vcc = 6, Gnd = 1, VfB = 5
LA7841 = LA7840
LA7845 = LA7840
LA7846 = 5 Vin, Vout = 3, Vcc = 7, Gnd = 2, VfB = 6
LA7848 Vina = 5, VinB = 6, Vout = 3, Vcc (+) = 7, Vcc (-) = 2
LA7876 Vina = 5, VinB = 6 Vcc (+) = 7, Vcc (-) = 2

STV9302 = see AN5522
STV9379 = See AN5522


TA8403 Vin = 4, Vout = 2, Vcc = 6, Vcc = 6,
TA8445 Vin = 2, Vout = 11, Vcc1 = 1 (9v), Vcc2 = 7 (26v), Gnd = 10, 50/60 =

TDA1771 Vin = 3, Vout = 1, Vcc = 9. Gnd = 5
TDA4865 Vin = 6, Vout = 5, Vcc = 1, Gnd = 4, VfB = 2
TDA8175 Vin = 7, Vout = 5, Vcc = 2, VfB = 1
TDA3653 Vin1 = 1, Vin2 = 3, Vcc1 = 9, Vcc2 = 6, Vou = 5, Gnd = 4
TDA8350 Vina = 1, VinB = 2, VoutA = 10, VoutB =, Vcc1 = 3, Vcc2 = 9, Ewin = 12, Ewout = 11
See tda8357 TDA8351 =
See TDA8357 TDA8356 =
TDA8357 Vina = 1, VinB = 2, VoutA = 7, VoutB = 4, Vcc1 = 3 (12v), Vcc2 = 6 (45V), Gnd = 5
TDA8358 Vina = 1, VinB = 2, Vcc1 = 3 (12v), Vcc2 = 9 (25V), VoutA = 4, VoutB = 10, Gnd = 6.7, Ewin = 5, Ewout = 8
TDA9302 = see LA78040

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Wiring Diagram Electrical Components Symbols House Home

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Mains Pulser

The pulser is intended to switch the mains voltage on and off at intervals between just under a second and up to 10 minutes. This is useful, for instance, when a mains-operated equipment is to be tested for long periods, or for periodic switching of machinery. Transformer Tr1, the bridge rectifier , and regulator IC1 provide a stable 12V supply rail for IC2 and the relay. The timer is arranged so that the period-determining capacitor can be charged and discharged independently. Four time ranges can be selected by selecting capacitors with the aid of jumpers. Short-circuiting positions 1 and 2 gives the longest time, and short-circuiting none the shortest.

Mains Pulser Circuit diagram:

In the latter case, the 10µF capacitor at pins 2 and 6 of the timer IC determines the time with the relevant resistors. The value of this capacitor may be chosen slightly lower. The two preset potentiometers enable the on and off periods to be set. The 1k resistor in series with one of the presets determines the minimum discharge time. The timer IC switches a relay whose double-pole contacts switch the mains voltage. The LEDs indicate whether the mains voltage is switched through (red) or not (green). The 100mA slow fuse protects the mains transformer and low-voltage circuit. The 4 A medium slow fuse protects the relay against overload.

Source :   http://www.ecircuitslab.com/2011/05/mains-pulser.html

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Best Start up Aid for PCs

Since one of the servers owned by the author would not start up by itself after a power failure this little circuit was designed to perform that task. 

The older PC that concerned did have a standby state, but no matching BIOS set-ting that allows it to start up unattended. Although a +5 V standby supply voltage is available, you always have to push a but-ton for a short time to start the computer up again. Modern PCs often do have the option in the BIOS which makes an automatic start after a power outage possible. After building in the accompanying circuit, the PC starts after about a second. Incidentally, the push-button still functions as before.

 

The circuit is built around two golden oldies: a NE555 as single-shot pulse generator and a TL7705 reset generator. The reset generator will generate a pulse of about 1 second after the supply voltage appears. The RC circuit between the TL7705 and the NE555 provides a small trigger pulse during the falling edge of the 1 second pulse. The NE555 reacts to this by generating a nice pulse of 1.1RC. During that time the output transistor bridges the above mentioned pushbutton switch of the PC, so it will start obediently. 

Other applications that require a short duration contact after the power supply returns are of course also possible.

Author : Egbert Jan van den Bussche – Copyright : Elektor

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Police Lights associate crystal rectifier Project

This circuit uses a 555 timer that is setup to each runn in associate Astable operative mode. This generates a nonstop output via Pin three within the type of a sq. wave. once the timers output changes to a high state this triggers the a cycle the 4017 4017 decade counter telling it to output consecutive sequent output high. The outputs of the 4017 ar connected to the LEDs turning them on and off.

Schematic


Parts List

1x - NE555 Bipolar Timer
1x - 4017 Decoded Decade
6x - 1N4148 Diode
1x - 1K Resistor (1/4W)
1x - 22K Resistor (1/4W)
2x - 4.7K Resistor (1/4W)
6x - 470 Resistor (1/4W)
1x - 2.2µF Electrolytic Capacitor (16V)
2x - BC547 NPN Transistor
2x - LED (Blue)
2x - LED (Red)
1x - 9V Voltage Battery 

 

Streampowers

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Quick Draw

The object of Quick Draw is to test your reaction time against your opponents. A third person acts as a referee and begins the duel by pressing S1, which lights LED1. Upon seeing LED1 go on, you try to outdraw your opponent by moving S2 from "Holster" position to "Draw" position before your opponent moves S3 from "Holster" to "Draw" position. Who ever gets there first will light the corresponding LED and will automatically prevent the other LED from lighting, clearly indicating a winner.

Source:www.home.maine.rr.com

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Low Power FM Transmitter

This article should satisfy those who might want to build a low power FM transmitter. It is designed to use an input from another sound source (such as a guitar or microphone), and transmits on the commercial FM band - it is actually quite powerful, so make sure that you dont use it to transmit anything sensitive - it could easily be picked up from several hundred metres away. The FM band is 88 to 108MHz, and although it is getting fairly crowded nearly everywhere, you should still be able to find a blank spot on the dial.

NOTE: A few people have had trouble with this circuit. The biggest problem is not knowing if it is even oscillating, since the frequency is outside the range of most simple oscilloscopes. See Project 74 for a simple RF probe that will (or should) tell you that you have a useful signal at the antenna. If so, then you know it oscillates, and just have to find out at what frequency. This may require the use of an RF frequency counter if you just cannot locate the FM band.

Description

The circuit of the transmitter is shown in Figure 1, and as you can see it is quite simple. The first stage is the oscillator, and is tuned with the variable capacitor. Select an unused frequency, and carefully adjust C3 until the background noise stops (you have to disable the FM receivers mute circuit to hear this).

Figure 1 - Low Power FM Transmitter

Because the trimmer cap is very sensitive, make the final frequency adjustment on the receiver. When assembling the circuit, make sure the rotor of C3 is connected to the +9V supply. This ensures that there will be minimal frequency disturbance when the screwdriver touches the adjustment shaft. You can use a small piece of non copper-clad circuit board to make a screwdriver - this will not alter the frequency.

The frequency stability is improved considerably by adding a capacitor from the base of Q1 to ground. This ensures that the transistor operates in true common base at RF. A value of 1nF (ceramic) as shown is suitable, and will also limit the HF response to 15 kHz - this is a benefit for a simple circuit like this, and even commercial FM is usually limited to a 15kHz bandwidth.

Capacitors
All capacitors must be ceramic (with the exception of C1, see below), with C2 and C6 preferably being N750 (Negative temperature coefficient, 750 parts per million per degree Celsius). The others should be NPO types, since temperature correction is not needed (nor is it desirable). If you cannot get N750 caps, dont worry too much, the frequency stability of the circuit is not that good anyway (as with all simple transmitters).

How It Works
Q1 is the oscillator, and is a conventional Colpitts design. L1 and C3 (in parallel with C2) tunes the circuit to the desired frequency, and the output (from the emitter of Q1) is fed to the buffer and amplifier Q2. This isolates the antenna from the oscillator giving much better frequency stability, as well as providing considerable extra gain. L2 and C6 form a tuned collector load, and C7 helps to further isolate the circuit from the antenna, as well as preventing any possibility of short circuits should the antenna contact the grounded metal case that would normally be used for the complete transmitter.

The audio signal applied to the base of Q1 causes the frequency to change, as the transistors collector current is modulated by the audio. This provides the frequency modulation (FM) that can be received on any standard FM band receiver. The audio input must be kept to a maximum of about 100mV, although this will vary somewhat from one unit to the next. Higher levels will cause the deviation (the maximum frequency shift) to exceed the limits in the receiver - usually ±75kHz.

With the value shown for C1, this limits the lower frequency response to about 50Hz (based only on R1, which is somewhat pessimistic) - if you need to go lower than this, then use a 1uF cap instead, which will allow a response down to at least 15Hz. C1 may be polyester or mylar, or a 1uF electrolytic may be used, either bipolar or polarised. If polarised, the positive terminal must connect to the 10k resistor.

Inductors
The inductors are nominally 10 turns (actually 9.5) of 1mm diameter enamelled copper wire. They are close wound on a 3mm diameter former, which is removed after the coils are wound. Carefully scrape away the enamel where the coil ends will go through the board - all the enamel must be removed to ensure good contact. Figure 2 shows a detail drawing of a coil. The coils should be mounted about 2mm above the board.

For those still stuck in the dark ages with imperial measurements (grin), 1mm is about 0.04" (0.0394") or 5/127 inch (chuckle) - you will have to work out what gauge that is, depending on which wire gauge system you use (there are several). You can see the benefits of metric already, cant you? To work out the other measurements, 1" = 25.4mm

NOTE: The inductors are critical, and must be wound exactly as described, or the frequency will be wrong.

Figure 2 - Detail Of L1 And L2

The nominal (and very approximate) inductance for the coils is about 130nH.This is calculated according to the formula ...

L = N² * r² / (228r + 254l)

... where L = inductance in microhenries (uH), N = number of turns, r = average coil radius (2.0mm for the coil as shown), and l = coil length. All dimensions are in millimetres.

Pre-Emphasis

It is normal with FM transmission that "pre-emphasis" is used, and there is a corresponding amount of de-emphasis at the receiver. There are two standards (of course) - most of the world uses a 50us time constant, and the US uses 75us. These time constants represent a frequency of 3183Hz and 2122Hz respectively. This is the 3dB point of a simple filter that boosts the high frequencies on transmission and cuts the same highs again on reception, restoring the frequency response to normal, and reducing noise.

The simple transmitter above does not have this built in, so it can be added to the microphone preamp or line stage buffer circuit. These are both shown in Figure 3, and are of much higher quality than the standard offerings in most other designs.

Figure 3 - Mic And Line Preamps

Rather than a simple single transistor amp, using a TL061 opamp gives much better distortion figures, and a more predictable output impedance to the transmitter. If you want to use a dynamic microphone, leave out R1 (5.6k) since this is only needed to power an electret mic insert. The gain control (for either circuit) can be an internal preset, or a normal pot to allow adjustment to the maximum level without distortion with different signal sources. The 100nF bypass capacitors must be ceramic types, because of the frequency. Note that although a TL072 might work, they are not designed to operate at the low supply voltage used. The TL061 is specifically designed for low power operation.

The mic preamp has a maximum gain of 22, giving a microphone sensitivity of around 5mV. The line preamp has a gain of unity, so maximum input sensitivity is 100mV. Select the appropriate capacitor value for pre-emphasis as shown in Figure 3 depending on where you live. The pre-emphasis is not especially accurate, but will be quite good enough for the sorts of uses that a low power FM transmitter will be put to. Needless to say, this does not include "bugging" of rooms, as this is illegal almost everywhere.

I would advise that the preamp be in its own small sub-enclosure to prevent RF from entering the opamp input. This does not need to be anything fancy, and you could even just wrap some insulation around the preamp then just wrap the entire preamp unit in aluminum foil. Remember to make a good earth connection to the foil, or the shielding will serve no purpose.

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