Homemade single tube FM radio ----- FM Radio

Introduction: There are many circuits and suits of the AM radio, and many are working very well. But you will find that the circuit of the simple FM radio is almost no. In fact, these circuits disappeared after transitioning from the era of tubes to the transistor era. In the end of the 1950s, several simple super-regenerated architectures occurred. After the detailed study of these circuits, I developed this simple FM radio circuit in combination with some excellent design of the modern regeneration circuit. This is an extraordinary work, with high sensitivity and selectivity, and has enough volume. Circuit layout Since this is a super-regenerative design, the layout of the component is quite important. The tuning capacitor C3 has three pins, faces you, the pin is facing, the middle of this foot, the pin on the left L1, one pin on the right. L1 is close to C3, but as far as possible to stay away from your hand. If your hand is too close to L1, it will be very difficult. The winding L1 of L1 determines the frequency of the radio, as in the antenna, is a major adjustment element in the hyperbupler circuit. Although it is a very important job, it is very easy to operate, free to find a diameter of 0.5-inch cylinder to make a model, with a naked copper line 20, (other wires can, but to maintain a certain shape) Circle, then taken back, pull the coil to 1 inches. Welding C2 on the midpoint of the coil, when the lead in the coil is welded to the PCB board, pay attention to the gap between the coil and the plate. Debug If the wiring is correct, you may hit four possibilities: 1 Receive the radio, 2 big noise 3 whistling 4 no. If you hear the radio, this is a good start. With another FM radio to compare your frequency error, you can adjust L1 and C1 to correct. If you hear a lot of noise, you should receive a radio. Carefully adjust C3 to receive anything. If you have heard the whistling or nothing, it is too strong or too weak. L1 can be drawn or compressed. Check whether the circuit is connected correctly. If there is no improvement, you need to change R4, change R4 to 20K or replace it with a 50K, preferably a variable resistor. The R4 is adjusted until it can be stably received. Once the circuit is working properly, then the variable resistance is changed, and the fixed resistance of the same resistance is replaced.

Our other product:

Professional lightning protection system for Tower	Professional FM Radio Station Equipment Package	FMUSER FU-1000C 1000W FM Transmitter With USB Audio Input Interface
FMUSER 200W FM Radio Broadcasting Package	Hotel IPTV Solution	FMUSER FSN-1000T V5.0 1KW FM Radio Broadcast Transmitter