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Radio circuit diagrams electronics projects

Radio circuit diagrams electronics projects for radio transmitter, radio receiver circuit, rf amplifiers, rf boosters and some other related RF circuits like: fm antenna booster, microwave transmitter and wireless modules.

MC2833 FM RF Transmitter

A very simple FM transmitter circuit can be constructed using this schematic diagram based on MC2833, designed for cordless telephone and FM communication equipment. It includes a microphone amplifier, voltage controlled oscillator and two auxiliary transistors.

This FM transmitter circuit , based on the MC2833 IC has an low drain current ( ICC =2.9mA typically ) and supports a wide range operating voltage ,from 2.8 to 9 volts .

Other features of this MC2833 FM transmitter circuit are : – 30 dBm power output to 60 MHz using direct RF output ,+10 dBm power output attainable using on–chip transistor amplifiers .
Crystal X1 connected at pin 16 and pin 1 ( trough a 5.1uH coil ) is fundamental mode, calibrated for parallel resonance with a 32 pF load.

The final output frequency is generated by frequency multiplication within the MC2833 IC. The RF output buffer (Pin 14) and Q2 transistor are used as a frequency tripler and doubler, respectively, in the 76 and 144 MHz transmitters.

The Q1 output transistor is a linear amplifier in the 49.7 MHz and 76 MHz transmitters, and a frequency doubler in the 144 MHz transmitter.
All coils used are 7 mm shielded inductors, CoilCraft series M1175A, M1282A–M1289A, M1312A or equivalent.

Power output is 9 + 10 dBm for 50 MHz and 76 MHz transmitters, and 9 + 5.0 dBm for the 144 MHz transmitter at VCC = 8.0 V. Power output drops with lower VCC.
Other transmitter frequency can be set , by modify the components value ai is shown in this table .
MC2833 fm transmitter components
This FM transmitter circuit need to be powered from a 9 volts DC power supply ( for full performance) .
MC2833 fm transmitter schematic circuit

LM1800 PLL Stereo Decoder

An very simple FM Stereo Demodulator circuit that use phased lock loop techniques to regenerate the 38kHz subcarrier can be constructed using the LM1800 integrated circuit .
The LM1800 integrated FM stereo demodulator has numerous features like :
automatic stereo/monaural switching , 45 dB power supply rejection ,wide operating supply voltage range ,excellent channel separation .

Particularly attractive for this circuit are the low external part count and total elimination of troublesome tuning coils , all tuning requirements are made using a single inexpensive potentiometer .

As you can see in the circuit diagram this lm1800 fm stereo demodulator has a 100mA stereo indicator lamp driver.
For this LM1800 Phase-Locked Loop FM Stereo Demodulator circuit , you will need an dc power supply that can provide an output voltage between 10 and 18 volts .

Also if you can not find the LM1800 Phase-Locked Loop FM Stereo Demodulator circuit on the market you can use the UA758 ic which is pin-to-pin compatible with LM1800 .
LM1800 Phase-Locked Loop FM Stereo Demodulator circuit

FM booster schematic circuit

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 gain .
To calibrate this circuit you need to adjust input/output trimmers (VC1/VC2) for maximum gain.
Input coil L1 consists of four turns of 20SWG enamelled copper wire (slightly space wound) over 5mm diameter former.

It is tapped at the first turn from ground lead side. Coil L2 is similar to L1, but has only three turns.
Both of the trimmers are 22pF value .This FM radio signal booster needs to be powered by a 12 volts DC power supply .

fm signal booster circuit schematic


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