Here is a simple FM Radio using an IC1 1260.This IC is a 16-pins. All the components used for this FM radio can be easily purchased in a market or can be taken away from your old Black & White TV set, radio e.t.c.
Most of FM radios work on 10.7MHz IF frequency but this on works on 5.5 MHz IF frequency. As a 10.7MHz IFT coils is hard to find in a market we used here 5.5MHz IFT coil which can be easily find in a market and also can be taken away from your old Black & White TV sets. Also 5.5MHz 3-pin ceramic filter used for this FM radio can also be easily find in a market.
Circuit and Working
The heart of this circuit is a transistor Q1 (BF494) and IC1 (LA1260) and using few resistors and capacitors, 5.5MHz ceramic filter and 5.5 MHz IFT coil.
Transistor Q1 (BF 494) together with coil L1 (5 turns of 23 SWG wires of 5mm air core), trimmer capacitor VC1 (2-22pF), resistors R1 (470K), R2 (470) and a capacitor C1 (102), C2 (103), C10 (10pF) makes an oscillator of frequencies of 93.5MHz-113.5 MHz. A 88.00MHz-108MHz input signal form an antenna( 75cm) and to a base of a transistor Q1(BF 494) through a capacitor C1 is mixed with 93.5MHz-113.5MHz oscillator and a 5.5 MHz IF frequency is taken away from a capacitor C3(33pF) and is connected to a pin 1 of 5.5MHz ceramic filter.
Next connect a pin 2 of X1 to a ground and pin 3 to a pin no: 1 of LA1260. Pin 2, pin 3 of IC1 are also connected ground with a capacitors C4, C4 (403). Pin 4 is connected to ground. Pin 5 is connected to +6V with a resistor R3 (6K8), pin 6 is connected +6V, pin 7 is connected to +6V through a D1 and R4.An AF output is taken away from a pin 8 of IC1 through an electrolytic capacitor C7 (10uF/25V). Capacitor C6 (103) is grounded. Pin 11 of IC1 is connected to ground with an electrolytic capacitor C9 (1uF/25V). Pin 13, 14 are ground. Pins 15, 16 are connected together and are connected to C8 (1uF/25V).
Construction and Testing
A vero board of size 5cm*7cm is suitable for your project. You can also build this on a PCB board given on an article. An inductor coil L1 can be made by winding 5 turns of 23 SWG wire on 5mm air core. You’ll need a 16-pin IC socket for your project. Place 16-pin IC socket on a middle of a veroboard. Place all the components on a veroboard as given on a circuit diagram and solder all the components on a vero board or on a PCB board.
Now we will test your FM radio. Connect a power supply of +6Volts to your FM radio. Connect an AF output from your FM radio to an AF amplifier. Turn on an AF amplifier and set a volume of AF amplifier to mid position. You’ll hear a hissing sound from a speaker of an AF amplifier.
Now is your FM radio is working and ready for using. Connect a 75cm long wire and connect to your FM radio. Take a small plastic screwdriver and gently tune VC1 until you’ll hear a station.
Also tune a 5.5 MHz IFT coil until you’ll hear clear and loud signal. You’ll see a LED1 glowing as soon as a signal is received.
So, your’ FM radio using LA1260 is working and ready for a using.*
C3: ( 33pF)
C4, C5: (403)
C6: ( 103)
C8, C9: ( 1uF/25V)
X1(3-pin 5.5MHz Ceramic Filter), T1 (5.5 MHz IFT coil, 16-pin IC socket, 5cm*7cm vero board, VC1, 6Volts battery, wires.