Mosquito repellers are popular to keep bugs away, as they use ultrasonic sound or chemical spray; but if it is always ON then they use much electricity. To solve this problem, we designed a timer-based mosquito repeller power saver circuit, it switches the repeller ON and OFF at fixed intervals to reduce power consumption and […]
Hobby Circuits
Simple LED Alert for Telephone Off-Hook Detection Circuit
This simple LED circuit detects voltage drops when we lift the handset, actively turning ON an LED to show that our telephone is in use. Also, circuit is good for old phones with no light alert and it is very useful for shared phones and stops call interruptions. Here, circuit runs on simple 3V battery […]
Electromagnetic Telephone Ringer Circuit
Electromagnetic Telephone Ringer Circuit helps us know when call comes and when there is no need connect to phone line. Also, this circuit is useful when there is no access or do not want to touch phone line, as it works by sensing electromagnetic field from ringing signal and then buzzer turns ON; furthermore, the […]
Tone Generator Doorbell Circuit using Dual IC 555 Timers
This tutorial explains a Tone Generator Doorbell Circuit using dual IC 555 timers, also the circuit is simple and works well when we press the button One IC works in astable mode and other in monostable mode and it is very important for making sound to run a 8Ω speaker. Also, the circuit needs 9V […]
9V Battery Powered Transistor Intercom Circuit
Intercom system is device for talking at short distance; so a 9V Battery Powered Transistor Intercom Circuit uses 9V battery which is good for home or office talk. Also, it uses only transistors which is easy to understand and works well. Furthermore, the circuit has mic and small speaker as sound and a BC547 transistors […]
Transistor Based Battery Heater Circuit
Transistor Based Battery Heater Circuit uses 12V DC with good heat and very portable; also circuit is good for outdoor, no-electric place, small incubator and emergency heat. Furthermore, it uses astable multivibrator with transistors and this transistors switch power transistor and run heat coils and finally, LED show if circuit is working. Circuit Working: Parts […]