In this text, an RC oscillator is used as a baud fee generator. If that you can be able to calibrate the frequency of such a circuit adequately competently (within a few percent) utilizing a frequency meter, it goes to work very neatly. However, it should smartly drift slightly after some time, and then…. Consequently, right here we current a small crystal-controlled oscillator. If you begin with a crystal frequency of two.45765 MHz and divide it by means of more than ones of 2, you may very effectively obtain the smartly-known baud charges of 9600, 4800, 2400, 600, 300, a hundred and fifty and seventy five. If you seem to be intently at this series, you are going to see that 1200 baud is lacking, because divider within the 4060 has no Q10 output!
If you don't want 1200 baud, this is not an issue. However, seeing that 1200 baud is utilized in observe more continuously than 600 baud, we've put a divide-by-two stage within the circuit after the 4060, within the type of a 74HC74 flip-flop. This yields a similar series of baud rates, through which 600 baud is missing. The trimmer is for the calibration purists; a 33 pF capacitor will frequently provide enough accuracy. The current consumption of this circuit may be very low (around 1mA), because of the usage of CMOS elements.
www.ecircuitslab.com
