RF Radio Circuits

Remote Operated Home Appliances Circuit

Suitable for operating, Lamps, Fan, Radio etc.., Small n easy unit Here is the circuit diagram of Remote Operated Home Appliances or Remote controlled Home appliances. Connect this circuit to any of your home appliances (lamp, fan, radio, etc) to make the appliance turn on/off from a TV, VCD, VCR, Air Conditioner or DVD remote […]

Circuit Keeps Wandering Children and Pets Nearby

The receiver circuit in Figure 1 sounds an audio alarm when the transmitter (Figure 2) moves beyond a designated perimeter. The transmitter, a voltage-controlled oscillator, operates at approximately 915 MHz in the unlicensed ISM (industrial/scientific/medical) band. It has a tuning voltage of 1.5V=3×R2/(R1+R2), which lets you easily adjust the frequency by varying the values of […]

RJ45 Network Card to IR Communication

This system, composed of two opto-insulated circuits, allows the data transmission per infra-red network device between two computers. For example, someone can transfer his files starting from his desktop computer to his laptop computer without using any cable. How? By using infra-red diodes. We have to connect a circuit to the 10/100 Mbps network card […]

300m FM Transmitter

This FM transmitter circuit is very simple and it has a acceptable transmission . The signal transited from this FM transmitter circuit can be received at almost 300 meters in open air .The circuit require a 3volts operating voltage and can be tuned anywhere in the FM band.The coil should be about 3mm in diameter […]

IR Music Transmitter and Receiver

Using this circuit, audio musical notes can be generated and heard up to a distance of 10 metres. The circuit can be divided into two parts: IR music transmitter and receiver. The IR music transmitter works off a 9V battery, while the IR music receiver works off regulated 9V to 12V. First diagram shows the […]

IR Remote Switch

Imagine the convenience of selecting TV channels using your remote and then pointing the same remote to your switchboard to switch on/off the fan or the tubelight. Here is a simple circuit to remotely switch on/off any electrical device through a relay using the normal TV/VCR/VCP/VCD remote control unit. It works up to a distance […]

Simple AM Radio Receiver

This circuit is essentially an amplified crystal set. The inductor could be a standard AM radio ferrite rod antenna while the tuning capacitor is a variable plastic dielectric gang, intended for small AM radios. The aerial tuned circuit feeds diode D1 which functions as the detector. A germanium type is far preferable to a silicon […]

Tuned Radio Frequency (TRF) Receiver

Superheterodyne receivers have been mass-produced since around 1924, but for reasons of cost did not become successful until the 1930s. Before the second world war other, simpler receiver technologies such as the TRF receiver and the regenerative receiver were still widespread. The circuit described here is based on the old technology, but brought up-to-date a […]

FM Booster

A low-cost circuit of an FM booster that can be used to listen programs from distant FM stations clearly. The circuit comprises a common-emitter tuned RF preamplifier wired around VHF/UHF transistor 2SC2570 ( C2570). this FM booster circuit is constructed using few common components( not require some special components ) and provide a very good […]

Mobile Bug Detector

his handy, pocket-size mobile transmission detector can sense the presence of an activated mobile phone from a distance of one-and-a-half metres. So it can be used to prevent use of mobile phones in examination halls, confidential rooms, etc. It is also useful for detecting the use of mobile phone for spying and unauthorised video transmission. […]