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 is from the time when photos were revealed in darkrooms. We found it in a 1968...
This high-gain circuit was found in an American publication from the 1990s. The circuit can use...
This circuit provides an output of 5 to 10 V at its output from inputs of 1.5 to 4.5 V. The output...