TREE

A simple PLL FM demodulator circuit using IC XR2212 is shown here. XR2212 is a highly stable, monolithic PLL (phase locked loop) IC specifically designed for communication and control system applications. The IC has 0.01 Hz to 300KHz frequency range, 4.5 to 20V operating voltage range, 2mV to 3Vrms dynamic range, high temperature range, TTL / CMOS compatibility and adjustable tracking range. The block diagram of a typical PLL FM demodulator circuit is shown below. PLL FM demodulator block diagram The working of a PLL FM demodulator is very easy to understand.The input FM signal and the output of the VCO is applied to the phase detector circuit. The output of the phase detector is filtered using a low pass filter, the amplifier and then used for controlling the VCO. When there is no carrier modulation and the input FM signal is in the center of the pass band (i.e. carrier wave only) the VCO’s tune line voltage will be at the center position. When deviation in carrier frequency occurs ( ...

BH1417 IC The circuit shown here is of a good Stereo FM transmitter that can transmit high quality signals up to a range of 70 feet. The circuit is based on BH1417 PLL stereo transmitter IC from Rhom semiconductors. The IC has separate audio processing sections for the left and right channels, pre emphasis circuit for improving signal to noise ratio, crystal control circuitry for accurate frequency locking, multiplex circuit for making sum ( left plus right) and difference ( left minus right) {see this article for better understanding – Stereo decoder circuit} etc. Another important feature of this IC is that the transmission frequency can be set using a 4 channel DIP switch. The IC can be powered from anything between 4 to 6V DC and has an output power around 20mW. At full output power the circuit consumes only 20mA and has a channel separation of 40dB.There are 14 possible preset transmission frequencies, starting from 88.7MHz and incrementing in steps of 0.2MHz that can be selected ...