Crystal variable oscillator (CB9506E)

Found in Radio Electronics from the 90s, this circuit can vary the frequency in small values around the crystal frequency.

Auto Bias for FET (CB6125E)
This configuration is from a 1964 US documentation valid for any FET. The range of power voltages...
Electronic Piggy Bank (CB16268E)
Only the right combination of the positions of the 6 rotary switches of 1 pole x 10 positions of...
Debuncer 4049 (CB24877E)
Another of the many anti-bounce circuits that we have in this section of our website. This one...