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This is the Simple Auto Tachometer Circuit Diagram. Anyone performing their own automobile tune-ups knows how important it is to know your engines speed. With this tachometer, you can measure your engines speed without any connections or annoying timing lights.   Simple Auto Tachometer Circuit Diagram  PC board layout and parts placement Notes Calibrate the unit as folows: a.    Set up this circuit:    Turn on the Tach and allow a few minutes for temperature stabilization. Set S2 to 4 cylinders and adjust R5 for a meter indication of 180 (1800 rpm). Set S2 to 6 cylinders and adjust R6 for a meter indication of 120 (1200 rpm). Set S2 to 8 cylinders and adjust R7 for a meter indication of 90 (900 rpm). To use the Tach, turn it on and let it sit for one minute to allow for temperature stabilization. Extend the antenna, select the right number of cylinders and hold the unit over the engine. If the reading is erratic or the needle jumps around, move th...

This is a simple LED as a diode Rectifier Circuit Diagram. In certain situations where the current is not high, we can use the famous LED (LED) and diode rectifier voltage power circuits. The LED can be used without problem in a rectification circuit, and also works in the power ratings. Pay attention not to exceed the maximum current of the LED in a wave rectifier.  Using LED as a diode Rectifier Circuit Diagram

Without any dedicated buck converter/white crystal rectifier driver IC, you'll safely drive several customary Hi-efficient white crystal rectifier modules victimization the battery power out there in cars. Here may be a safe and easy white crystal rectifier driver designed for 12V cars. In the Automobile White crystal rectifier wiring, fastened transformer IC1 (7805) provides a gentle voltage of 5V across C2. Resistors R1 limits the present flow through the white crystal rectifier D1 (3v6/350mA) with the assistance of semiconductor T1 (and T2), i.e. parts R1, T1 (and T2) offer a relentless current to D1. Use a decent sink for T1. This crystal rectifier unit offers a relentless lightweight output for input voltages starting from eight to eighteen volts! Auto White LED Circuit Schematic

In this circuit, an HA-4900 series comparator is used in conjunction with a D/A converter to form a simple, Data accretion System Circuit Diagram versatile, multichannel analog input for a data acquisition system. The processor first sends an address to the D/A, then the processor reads the digital word generated by the comparator outputs, lb perform a simple comparison, the processor sets the D/A to a given reference level, then examines one or more comparator outputs to determine if the inputs are above or below the reference. A window comparison consists of two such cycles with two reference levels set by the D/A. One way to digitize the inputs would be for the processor to increment the D/A in steps. The D/A address, as each comparator switches, is the digitized level of the input. While stairstepping, the D/A is slower than successive approximation; all channels are digitized during one staircase ramp.

DC Motor Speed Controller Circuit Diagram. This circuit takes advantage of the voltage drop across bridge rectifier diodes to produce a 5-position variable voltage supply to a DC fan or other small DC motor. It is not as efficient as a switch-mode circuit but it has the virtues of simplicity and no switching hash. The four full-wave bridges are connected so that each has two pairs of series diodes in parallel, giving a voltage drop of about 1.4V, depending on the load current. DC Motor Speed Controller Circuit Diagram The rotary switch should have "make before break" contacts which should be rated to take currents up to about an amp or so. For higher currents, higher rated bridge rectifiers and a suitably rugged rotary switch (or solenoids) will be required. If you want smaller voltage steps, you could use the commoned AC inputs on the bridge rectifiers to give intermediate steps on the speed switch. Author: Stephen Butcher,

This basic circuit is simple to create and the tool's are not critical . Most of them can be found in your junk parts box . The L1 antenna coil can be made by close winding 8 to 10 turns of 22 gauge insulated hookup wire around a 1/4 inch form such as a pencil . You can exeprement with the size of the copile and the number of  turns to see how it affects the frequency and singnal out put of the oscilatter . You ought be able to pick up its signal with a standard FM radio receiver . The signal in ought be coupled by a disc capacitor of about 0.1 uF to stage in main of it . Author            Saifullah soomro

The whole project was developed on a friend's request. Its purpose was to remotely monitor the water-level in a metal tank located in the attic by means of a very simple control unit placed in the kitchen, some floors below. Mains requirements were: No separate supply for the remote circuit Main and remote units connected by a thin two-wire cable Simple LED display for the main unit Battery operation to avoid problems related to mains supply and water proximity As the circuit was battery operated a low current consumption was obviously welcomed The very small remote unit is placed near the tank and measures the water level in three ranges by means of two steel rods. Each range will cover one third of the tank capacity: Almost empty - signaled by means of a red LED (D3) in the control unit display About half-level - signaled by means of a yellow LED (D2) in the control unit display Almost full - signaled by means of a green LED (D1) in the control unit display Simple Water Level...

Description    This dual polarity power supply is easy to build, requires few parts, and is adjustable from 0-15 volts. It is great for powering op amp circuits, as well as other circuits that require a dual supply voltage. Circuit diagram Parts C1, C2 2200uF 35V Electrolytic Capacitor C3, C4, C5, C7 1uF 35V Electrolytic Capacitor C6, C8 100uF 35V Electrolytic Capacitor R1, R4 5K Pot R2, R3 240 Ohm 1/4 W Resistor BR1 2A 30V Bridge Rectifier U1 LM317 Adjustable Positive Regulator U2 LM337 Adjustable Negative Regulator T1 30V Center Tapped 2 Amp Transformer S1 SPST 2 Amp Switch MISC Heatsinks For U1 And U2, Line Cord, Case, Knobs For Pots, Wire Notes Since this project operates from 120 (or 220, or 240, etc.) volts AC, it MUST be built inside a case. U1 and U2 get quite hot and will require heatsinks. A fan is usually not needed. You can, of course, add a volt and amp meter. U1 and U2 can only go down to a minimum of +-1.2V. If you need to go lower, you can add two 1N4003 diodes...

This is a Simple Directional Signals Monitor Circuit Diagram . A unijunction transistor audio oscillator drives a small speaker. The oscillator`s frequency is determined by resistor R2 and capacitor C2. The ope rating voltage is supplied from the car`s turn-signal circuit(s) through Dl and D2. The diodes conduct current from the blinker circuit that is energized, and prevent stray current flow to the other blinker circuit. Simple Directional Signals Monitor Circuit Diagram

This is a compact three transistor, regenerative receiver with fixed feedback. It is similar in principle to the ZN414 radio IC which is now no longer available. The design is simple and sensitivity and selectivity of the receiver are good. Notes: All general purpose transistors should work in this circuit, I used three BC109C transistors in my prototype.The tuned circuit is designed for medium wave. I used a ferrite rod and tuning capacitor from an old radio which tuned from approximately 550 - 1600kHz. Q1 and Q2 form a compund transistor pair featuring high gain and very high input impedance. This is necessary so as not to unduly load the tank circuit. The 120k resistor provides regenerative feedback,between Q2 output and the tank circuit input and its value affects the overall performance of the whole circuit. Too much feedback and the circuit will become unstable producing a "howling sound". Insufficient feedback and the receiver becomes "deaf". If the circuit o...

Here is a phase-shift audio oscillator with excellent distortion characteristics thanks to “softened” diode limiting provided by the 1N914 and resistor divider and degenerated gain provided by the 68 ohm emitter resistor. For minimum distortion, increase the 68 ohm resistor to a point just below where oscillation stops. A simple buffer may be added for driving lower impedance loads. The output amplitude will be about 5 volts p-p but one of the 1N914 ’s 10k divider resistors may be changed for a different output amplitude. The circuit will work well with a power supply voltage other than 9 volts but the 68 ohm resistor may need adjustment

Telephone line Based Audio Muting and Light-On Circuit . Very often when enjoying music or watching TV at high audio level, we may not be able to hear a telephone ring and thus miss an important incoming phone call. To overcome this situation, the circuit presented here can be used. The circuit would automatically light a bulb on arrival of a telephone ring and simultaneously mute the music system/TV audio for the duration the telephone handset is off-hook. Lighting of the bulb would not only indicate an incoming call but also help in locating the telephone during darkness. . Telephone line Based Audio Muting and Light-On Circuit diagram :   Telephone line Based Audio Muting and Light-On Circuit Diagram  . On arrival of a ring, or when the handset is off-hook, the inbuilt transistor of IC1 (opto-coupler) conducts and capacitor C1 gets charged and, in turn, transistor T1 gets forward biased. As a result, transistor T1 conducts, causing energisation of relays RL1, RL2, and RL3...

 This is an IC Based Amplifier circuit. This is Using Lm1895N Mini Amplifier Circuit Diagram. This circuit with 3-V to 9-V supplies, this amplifier can provide from 100-mW to 1-W output into a 4 and bandwidth is approximately 20 kHz @ 3 dB. This circuit is useful for low-power and battery applications. Drain is 80 mA @ 3 V or 270 mA @ 9 V at maximum signal conditions. Using Lm1895N Mini Amplifier Circuit Diagram

Speed ​​Control of DC Motor PWM Circuit Diagram. Often, people try to control small DC motors with a variable resistor type potentiometer connected to a transistor. This system until works well but it generates heat and thus loses power. This circuit is a simple circuit for modulating the pulse width for controlling the DC motor, it eliminates this problem.  Speed ​​Control of DC Motor PWM Circuit Diagram The circuit is capable of controlling the engine speed pulses (PWM), these pulses have a duration variable to change the speed of the motor. The longer the pulses lead, the faster the motor will rotate, and vice versa. R1 1 Meg 1/4W Resistor R2 Potentiometer 100K C1 0.1uF 25V Capacitor Ceramic Disc C2 0.01uF 25V Capacitor Ceramic Disc Q1 MOSFET IRF511 or IRF620 U1 4011 CMOS NAND S1 KEY M1 Motor  The resistor R2 adjusts the speed of the oscillator and thus the speed of the motor, the motor can be any DC motor that operates from 6V and having no more powe...

This is the schematic design of HiFi Expandor Circuit with De-emphasis . The circuit is based NE570. The NE570 can be used to construct a high performance compandor suitable for use with music. This type of system can be used for noise reduction in tape recorders, transmission systems, bucket brigade delay lines, and digital audio systems. The circuits to be described contain features which improve performance, but are not required for all applications.  HiFi Expandor Circuit  Diagram  The expandor to complement the compressor is shown in the above circuit. Here an external op amp is used for high slew rate. Both the compressor and expandor have unity gain levels of 0dB. Trim networks are shown for distortion (THD) and DC shift. The distortion trim should be done first, with an input of 0dB at 10kHz. The DC shift should be adjusted for minimum envelope bounce with tone bursts. When applied to consumer tape recorders, the subjective performance of this system is excellent....

1000Watt Audio Power Amplifier Blazer Circuit This is a audio power amplifier Blazer circuit provides up to 1000Watt . This fascinating routes several sensible bass and treble alive. Importantly ought to opt for Power offer supply, that has been fairly high voltage category 70Vdc GND -70V 10A is that the current low level. The transistors are 2SC3858 (NPN) and 2SA1494 (PNP), and have high bandwidth, wonderful safe operating space, high linearity and high gain. Driver transistors are 2SC5200 (NPN) and 2SA1943 (PNP). All devices are rated at 230V, with the facility transistors having a 150W dissipation and also the drivers are 50W. This circuit describes an amplifier, power offer and tests procedures that are all inherently dangerous. Nothing described during this article ought to even be thought-about unless you're totally experienced, grasp specifically what you're doing, and are willing to require full 100% responsibility for what you are doing. There are aspects of the lo...

Full Power Mobile Phone Jammer Circuit Diagram .To day if we are talking about expert Cell phone Jammers we are conversing about this schematic underneath. First off all you should be very very cautious how to use this apparatus. Its completely illegal and so the reason. I post this Circuit is only for educational and testing causes. This type of apparatus is being utilised by security for VIPS, particularly at their limousines to avoid blasting device initiating while the vehicle passes from the goal cell phone-bomb. Off course there are those who use it to make a antic or to make the persons crazy in the rectangle block you are. The power of the jammer is currently sufficient to do your thing, but certainly you can place a 30W linear power amp at the RF output and impede a much wider locality. So, Be pleasant individual with that and recall that there are people who may need desperately to obtain or make a call and one of them could be you! And if you can't oppose of functio...

Often, for certain low voltage lighting systems; you would like to turn off the lights during the bright light of the day.  Most commercial day/night switches are designed for AC lighting.  This hobby circuit below was designed for a 12v DC system.  But, it could be modified for other voltage as well.  It uses an inexpensive photo-transistor as the light detector.  An n-channel FET is used to switch power to the lights.  A transistor circuit is included to provide some hysteresis.   This keeps the circuit from fluttering the light during the transition from day to night and night to day.  It is recommended that a plastic tube be placed over the transistor to prevent it from being illuminated by the lights it is controlling.  By selecting the appropriate power FET, the circuit could control over 100 watts worth of 12v lighting.   (July 22, 2008) Source: DiscoverCircuits

Designing various electronic circuit system (synthesizer, modem, decoder, data converter, etc) of ten need a frequency modulator subsystem. An FM modulator is very easy to build with TC9400 since the it has very good linearity as V/F converter. While Vin determines the amount of modulation (FM deviation) around the center frequency, the potentiometer determines the center frequency. Vin can be negative as well as positive. Superlinear FM Circuit Diagram

This post share about Mobile Phone charger circuits, previously you can see other Phone Battery Charger Circuit   or Charger Circuit  . This Charger ciruit use to charging phone battery using IC 7805 for plus voltage regulator or & 7905 for min voltage regulator.  Below is a schematic circuit adapter, power supply , or battery charger (for gadgets, mobile phones , MP4player, smartphone) that is equipped with a 5V voltage stabilizer : Diode Bridge diode bridge, known as a diode bridge is used for the rectifier circuit current ( rectifier ) from AC to DC . to make the diode bridge properly you need to know the type of diode to be used, to suit your needs. example: to make the power supply 12 Volt 3 ​​Ampere diode type 1N5401 is needed, for more detail how to choose the right type of diode to the adapter. Voltage stabilizers are commonly used are the 78XX or 79XX type LM, XX indicates the maximum voltage output is generated. see the example in the circuit schem...