This circuit is one of many that the reader can find in this section for testing crystals. The circuit uses an indicator LED. Transistor Q1 determines the maximum crystal frequency that can be tested.
This circuit generates sinusoidal signals that depend on the input oscillator. The circuit is from...
This input stage has unit gain but a high input impedance and low output impedance. The circuit is...
The figure shows how to increase the output voltage of a 7812 IC with a zener diode. Other...