Intercom system is device for talking at short distance. 9V Battery Powered Transistor Intercom Circuit uses 9V battery which is good for home or office talk. It uses only transistors which is easy to understand and works well. The circuit has mic and small speaker as sound. BC547 transistors make sound loud and 2N2222 transistor […]
Transistor Based Battery Heater Circuit
Transistor Based Battery Heater Circuit uses 12V DC with good heat and very portable. Circuit is good for outdoor, no-electric place, small incubator and emergency heat. It uses astable multivibrator with transistors. Transistors switch power transistor and run heat coils. LED show if circuit is working. Circuit Working: Parts List: Component Value Quantity Resistors (All […]
Ultrasonic Mosquito Repellent Circuit
Mosquitoes are small bugs which are very annoying. They also spread bad sickness like malaria and dengue. This Ultrasonic Mosquito Repellent Circuit idea is to use high sound especially ultrasonic to above 20 kHz to scare mosquitoes. Ultrasonic sound can disturb them and make them go away. This simple circuit makes that sound. Mosquitoes do […]
Simple Boost Converter LED Torch Circuit using IC MAX660
Simple Boost Converter LED Torch Circuit using IC MAX660 is small but useful light tool. This project use MAX660 chip to make LED torch work well. MAX660 boost 3V battery to higher voltage and can light many LEDs. It is good for battery devices needing more voltage and with no inductor needed. Circuit design also […]
Simple QRP Antenna Tuner Circuit for RF Applications
QRP is word in ham radio which means to send signal with low power. It come from Morse code. ‘QRP’ say “lower your power” and this QRP use power rules like: Simple QRP Antenna Tuner Circuit for RF Applications help send signal better. It connect low power radio to antenna. Tuner fix mismatch, stop power […]
Designing a UJT-Based Audio Tone Generator Circuit
Designing a UJT-Based Audio Tone Generator Circuit is easy and fun. It makes music sound like small instrument. It use UJT as relaxation oscillator. Push buttons change frequency with different notes. Sound goes to speaker after amplifier. Press button, tone change and w UJT 2N2646 will make right frequency. Transistor boost the sound from speaker. […]