Radio circuit diagrams

Q- Multiplying Loop Antenna

This circuit is designed to be used in conjunction with the standard 4 foot square loop used in MW for long distance reception.

2 Transistor FM Transmitter

This circuit may be tuned to operate over the range 87-108MHz with a range of 20 or 30 metres.

FM Transmitter Circuit

An low power FM Transmitter using an op-amp as the audio preamp and a single transistor as the RF amplifier.

TV Transmitter

This is an Analogue TV Transmitter. Sound modulation is type FM with a 5.5MHz carrier and video transmission is PAL. Frequency is adjustable via C5 and tunes 54 to 216Mhz with components shown. This is suitable for countries using TV systems B and G.

Cellular Phone calling Detector

Flashes a LED when detecting an incoming call Powered by one 1.5V cell

FM Receiver

An FM regenerative receiver using a single FET and one audio amplifier IC

Long Range FM Transmitter

With a good matching 50-ohm ground plane antenna or multi-element Yagi antenna, this transmitter can provide reasonably good signal strength up to a distance of about 2 kilometres.

Medium Wave Active Antenna

This is a compact three transistor, TRF receiver with fixed feedback. It is similar in principle to the ZN414 which is now replaced by the MK484. The design is simple and sensitivity and selectivity of the receiver are good.

4 Transistor Transmitter

This circuit provides an FM modulated signal with an output power of around 500mW.

Radio Friendly Power Supply

Power supplies should not create any unwanted interference across the radio spectrum. Switch mode power supplies are one of the strongest sources of interference, and harmonics can be heard throughout long, medium and short wave bands. This power supply, is extremely noise free, and therefore radio friendly. In addition, it has a very high rejection of line frequency and is suitable for powering receivers and small power transmitters.