Scoring game circuit

Description. A simple scoring game circuit that can be used for all occasions when a dice is needed.The circuit is based on a NE555 timer,a 74LS192 counter,a74LS247 decoder and a & segment LED display.The timer IC1 will produce the clock for the counter IC(IC2) whose frequency is determined by R1 and C2.When S2 is pressed the IC2 will count in up mode and when S3 is pressed the IC2 will count in down mode.The IC 3 will decode the count to display it on the seven segment LED display .Thats about the working of the circuit.The circuit is designed strictly…

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Aircraft radio circuit

Description. Here’s a low cost radio circuit that can be used to listen to the radio conversations between aircrafts. The radio circuit based on transistor 2N918 and diode 1N82 receives in the 220Mhz to 400Mhz range. Capacitor C1 and inductor L1 forms the tank circuit for tuning. Diode D1 performs the detection. Transistor T1 performs the necessary amplification. The out put audio signal is just enough to drive a small headphone. For driving speakers. Circuit diagram with Parts list.  Notes.  Use a 45cm long wire for antenna, For L1 make 2 turns of 22 AWG magnetic wire on a 5/32…

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Modified lamp dimmer circuit

Description. This is a modification of the circuit Simple Lamp Dimmer/Fan Regulator  previously  posted here. The working of the circuit is same as that of the previous, but in addition a snubber circuit consisting of resistor R4 and capacitor C3  is included to improve the performance of the triac T1. A fuse is also included for better safety. I think this is the better circuit to try . Circuit diagram with Parts list . Notes. No matter how  what ever may be the load lamp,fan , heater or anything it should be rated less than 200 Watts. No matter how …

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Two mode night light circuit

 Description. Here is a versatile night light circuit that can be used in two modes. The dimmer mode and a flashing mode. The circuit is based on dual opamp LM 358  and associated components. The first opamp IC1a is wired as a pulse generator and the second opamp is wired as a comparator. When the switch S1 is open the circuit is in dimmer mode where the intensity of the lamp can be varied by varying the POT R9. When the switch S1 is closed the circuit works in the flashing mode where the rate of flashing can be varied…

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3 W Stereo amplifier using MAX 7910

Description. A straight forward circuit diagram of a 3W stereo amplifier circuit using MAX 7910 IC is given here. This circuit is ideal for small power audio applications like portable CD players or radio sets. The circuit is designed strictly as per the datasheet and found to be working great. The MAX9710  a stereo audio power amplifier IC capable of delivering  3Watts  of out put to 4 Ohm loads. MAX9710 can be operated from a  single 4.5V to 5.5V power supply, makes it ideal for hand held applications. The IC also features thermal overload protection. Circuit Diagram with Parts list. …

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Battery Level Indicator

Simple Battery Level Indicator Description Here is a easy to build low battery level indicator circuit that produces a visible indication by flashing a LED when the battery voltage drops below a predetermined voltage.The circuit is based on Panasonic’s  IC MN13811G   and a efficient flasher based on transistors Q1&Q2.Here when the battery voltage drops below 2.4  V the output of the IC is activated and the flasher starts flashing.This circuit here is an ideal one for monitoring the level of all types of 3V batteries.The circuit is power efficient with a  idle current drawing as less as 1 uA  ,…

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Light activated switch circuit

A Simple Light activated switch Description. This is the circuit diagram of a light activated switch based on National Semiconductors comparator IC LM 311 and a LDR. The circuit is based on a voltage comparator circuit wired around IC 1.The non inverting in put of IC1 is given with a reference voltage of 6V using resistors R3 and R4. The input to the inverting input will be the voltage across the LDR that is light dependent. At darkness the resistance of the LDR will be high and so do the voltage across it. At this condition the voltage at the…

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Light to Frequency converter circuit

A simple Light to Frequency Converter Introduction. Here is the circuit diagram of a effective light to frequency converter circuit that can be used for variety of applications such as light intensity measurement,fun etc. The circuit is based on TLC555, the CMOS version of famous timer IC NE 555. A photo diode is used for sensing the light intensity.The timer IC is wired in astable mode.The leakage current of the reverse biased photo diode is proportional to the light intensity falling on it.This leakage current charges the capacitance C1.When the capacitor voltage reaches 2/3 of the supply voltage the out…

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Audio level meter circuit

Audio Level Meter Description A simple and low cost audio level meter circuit that can be used to measure the audio level of your sound source.This circuit is a valuable tool for those who are interested in audio circuits. The circuit is designed with a flat frequency response in the range of  20Hz to  50Khz. Input sensitivity is 100mV for a FSD on a 100uA ammeter.The circuit is build based on on two common emitter amplifiers, the first stage has a preset resistor R3 (1K) which may be adjusted for a FSD. The last stage is biased to operate at…

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AM Transmitter circuit

Simple AM Transmitter Description Here is the circuit diagram of a simple AM transmitter circuit that can transmit your audios to your backyard.This circuit is designed with limited  power output to match the FCC regulations and still produces enough amplitude modulation of voice in the medium wave band to satisfy your personal needs.You will love this!. The circuit has two parts , an audio amplifier and a radio frequency oscillator. The oscillator is built around Q1 (BC109) and related components. The tank circuit with inductance L1 and capacitance VC1 is tunable in the range of 500kHz to 1600KHz. These components…

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