Multi-purpose signal generator diagram made by μpc1651

Crystal oscillator

Quartz Oscillator 3225 20M OSC

The signal generator circuit made with μpc1651 is shown in the figure. IC1 and C1 form a low frequency oscillator of about 400HZ; IC2 and C3 form a high frequency oscillator of about 37MHZ. The low frequency signal output by C2 modulates the high frequency signal.

The harmonics of the high-frequency oscillator can display black and white strip signals on the TV's three channels or other channels for testing the TV. The signals output from point A and point B are used as detection signal sources for low frequency and image channels respectively. Changing the C3 to a quartz crystal stabilizes the oscillation frequency, as shown by the dotted line in the figure. If you replace the C3 with a small socket (note that the wiring is as short as possible), then insert a crystal oscillator of different frequency to make the intermediate frequency signal source of the recorder and TV. The frequency of the crystal oscillator can be selected with reference to the following values: 465 KHZ, 10.7 KHZ, 6.5 KHZ, 4.43 MHz, 37 MHz.