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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Single chip FM transmitter circuit

Single chip FM transmitter Description Here’s a single chip FM transmitter circuit using Maxim semiconductors IC MAX2606. The MAX2606 is a compact, high-performance intermediate frequency VCO specially designed for wireless communication circuits. They have monolithic construction with low-noise and a low-power operation in a compact 6-pin SOT23 packing .Th1s low-noise IC feature an on-chip varicap diode and feedback capacitances that avoid the need for external tuning components, making the MAX2606 perfect for portable systems. Only an external inductor is needed to set the oscillation frequency.In addition to this, an integrated differential output buffer is also there for driving a mixer…

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150 Watt amplifier circuit

Low Cost 150 Watt Amplifier Circuit Description This is the cheapest 150 Watt amplifier circuit you can make,I think.Based on two Darlington power transistors TIP 142 and TIP 147 ,this circuit can deliver a blasting 150 W Rms to a 4 Ohm speaker.Enough for you to get rocked?;then try out this. TIP 147 and 142 are complementary Darlington pair transistors which can handle 5 A current and 100V ,famous for their ruggedness. Here two BC 558 transistors Q5 and Q4 are wired as pre amplifier and TIP 142 ,TIP 147 together with TIP41  (Q1,Q2,Q3) is used for driving the speaker.This…

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100 Watt inverter circuit

100 Watt Inverter Description Here is a 100 Watt inverter circuit using minimum number of components.I think it is quite difficult to make a decent one like this with further less components.Here we use CD 4047 IC from Texas Instruments for generating the 100 Hz  pulses  and four 2N3055 transistors for driving the load. The IC1 Cd4047 wired as an astable multivibrator produces two 180 degree out of phase 100 Hz pulse trains.These pulse trains are  preamplifed by the two TIP122 transistors.The outputs of the TIP 122 transistors are amplified by four 2N 3055 transistors (two transistors for each half…

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Hi Fi Amplifier circuit

Hi Fi Amplifier Circuit – 2X12 Watts Description. Here is the circuit of a 2X12 watt H iFi  amplifier circuit using IC TDA 2616 from Phillips.A quiet simple and robust circuit using very less components.This makes the circuit ideal for a portable power amplifier.The circuit delivers 12 Watts power on  8 Ohm speaker for each channel at +/- 12 V dual supply. The TDA2616 is a  stereo power amplifier IC comes  in a 9-lead single-in-line (SIL9) plastic power package (SOT131). This IC is  specially designed for mains fed amplifier circuits, such as stereo radio,tape  and television .The IC has good…

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Mini Audio Amplifier circuit

Mini Amplifier Circuit Description Here is a simple and humble 2 Watts mini audio amplifier circuit suitable for small pocket radios and other portable audio gadgets.The circuit is based on Phillips Semiconductors IC TDA 7052.The amplifier can be run even from a 3V Mercury button cell.This makes it ideal for battery operated gadgets. The IC TDA7052 is a mono output amplifier coming in a 8-lead DI package (DIP). The device is mainly designed for battery-operated portable audio circuits. The features of TDA 7052 include ,no external components needed,  no switch-on or switch-off click sounds , great overall stability ,very low…

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