This circuit uses a common multimeter on the voltage scale. The calibration of the scale should be done based on transistors with known gains.
This circuit is from the manual of the components used, from the 80s. The circuit is valid for...
This circuit from the 1980s uses an operational amplifier that is uncommon today. The circuit can...
This "debouncer" was found in Popular Electronics, using TTL technology. For this reason, it can be...