Here the simple and low cost FM transmitter which powered using two transistors. This circuit may be tuned to operate over the range 87-108MHz with a range of 20 or 30 metres. The circuit works with 9V power supply, use regulated power supply for better quality. The coil L1 was consist of 7 turns on… Read More »
This is a simple, well designed 1.5 Watt FM Transmitter circuit using power transistor 2N2219A. This circuit should be able to cover 1-2 KM range. It use +5-30V power supply to work. Refer to the above diagram, the input source is an electret condenser microphone (you may try to use other input sources) and signal… Read More »
If it is desired to connect a video signal originating from a camera or other video source to a normal TV set, you will need this modulator. The audio and video signal is converted into a UHF TV signal so that the signal can be received through the TV antenna input. In certain countries (find… Read More »
This is the ultrasonic distance detector or sonar ranging system which can be used for general purpose. There are kit version available on the market, but of course the price is 3x more expensive than if you build your own sonar ranging system. Some application may use this circuit such as robot applications, body height… Read More »
This is the schematic diagram of Infrared (IR) cordless headphone. Maybe it also can be called “wireless headphone”, but it use infrared as sound signal carrier. It use a pair of circuit diagrams that are IR transmitter and IR reveiver. Using this low-cost project one can reproduce audio from TV or other electronic devices without… Read More »
This kind of circuit is a helpful device for testing of infrared (IR) based remote control transmitters utilized for TVs and VCRs and so forth. The IR motions from a remote control transmitter are sensed by the IR sensor module in the analyzer and its output at pin 2 goes low. This thusly switches on… Read More »
The circuit, consisting of an infrared transmitter-receiver pair, utilizes IR beam transmission to switch the toy car “on” or “off’, yeah… it will be only switching on and switching off, you may modify this circuit to make the toy car to turn left or right. To operate the toy car, you have to hold the… Read More »
This is a ultrasonic motion detector (or movement detector) circuit. The circuit claimed has a high movement sensitivity. Even air moving (hot air rising, wind blowing) will trigger it when the trimpot is set near the most sensitive position. The transmitter sends out a steady ultrasonic tone at 40kHz. At this frequency the wavelength is… Read More »
Above diagram is a very easy and efficient receiver for actuating garage doors, starter motors, alarms, warning systems and many some other possibilities. The SCR, which has a extremely low trigger current of 30 uA is typical — it demands an input electricity of just 30 uW to activate the relay. A high Q tuned… Read More »