Small stereo FM transmitter circuit

This article introduces to you a small stereo FM transmitter with BA1404 as the core. Because many friends are very enthusiastic about it and asked me about its information, I put it up. In fact, the application of BA1404 has been introduced in many electronic magazines and newspapers. It is not new, but it is indeed very practical. BA1404 is a dedicated integrated circuit for FM radio transmission produced by ROHM Company of the United States. It has a high degree of integration and requires few peripheral components. It works reliably and has a wide adaptable power supply voltage range. It can still work normally when it is as low as 1.5V. It is very suitable for production under amateur conditions. Various radio transmitting devices. Since I don’t have a scanner, I can only draw a typical circuit in PROTEL and its internal functional block diagram and pin description diagram in WORD to introduce it to you. It is said that this circuit can reach a distance of 1000 with a higher sensitivity FM radio. rice, you can go to trial production, as shown in Figure 1. The internal structure and pin diagram are shown in Figure 2. It is particularly pointed out that it is difficult to find a 38KHz crystal oscillator. A 57P capacitor can be used between pins 5 and 6 of the balance circuit to work instead, but the three-dimensional effect is not too obvious! With it you can create your own small stereo radio station! It should be noted that the transistor used in the power amplifier stage in the original picture is 2SC8050. In fact, everyone knows that the highest frequency of 2SC8050 is about 100MHz. It is very inappropriate to use it here. It will cause a sharp fever and burn out in a short time due to excessive power loss. , it is better to use domestically produced medium-power tubes such as 3DG130C or 3DG12C and add a heat dissipation cap. For example, the effect will be better if the special launch tubes such as D40 and D50 made in Taiwan are used, but the working point needs to be readjusted. Note: Due to my negligence, the power amplifier stage is not connected to the power supply. The upper part of T1 should be connected to the +4.5-6V power supply terminal. Based on the last circuit diagram, an output filter circuit is added to make the circuit more complete and the frequency performance better.