This circuit is from a March 1967 Radio Electronics. The circuit applies to general purpose SCRs such as the TIC106, C106 and others. The test is done by increasing the gate voltage to the trigger point.
This headphone amplifier using a pickup coil can be used as an extension for devices such as TVs,...
This rapid response amplifier uses an integrated one that is not common today but can be...
This low noise microphone preamplifier circuit was found in American documentation from the 90s....