This is a design circuit for stereo encoder. This circuit is using BH1417 Stereo Encoder. This circuit using with pre-emphasis, limiter so that the music can be transmitted at the same audio level, low pass filter that blocks any audio signals above 15 KHz to prevent any RF interference and crystal based stereo encoder for stereo transmission. This is the figure of the circuit.
The BH1417 single chip IC can be supplied with 6 - 15V voltage, consumes only around 25mA while providing very sound quality and improved 40dB channel separation. The IC is only available in SOP22 IC case and this may be an inconvenience for some folks. On the other hand, because the chip is smaller than regular DIP-based ICs it is possible to fit the entire stereo coder on a small PCB. This IC is requires 7.6MHz crystal oscillator which is pretty hard to find. The good news is that you can use 7.68 MHz crystal instead. In fact our BH1417 stereo encoder prototype uses 7.68 MHz crystal. This has absolutely no effect on stereo encoding process, we have tested it and stereo sound is crystal clear.
