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 was obtained from HAM Radio magazine in an 80's issue. The FETs are types of the time...
This circuit generates noise pulses for audio equipment probes. The circuit is from a 90’s 303...
This circuit was found in a 1970s General Electric documentation. This circuit already used an...