Multipurpose temperature control (CB21368E)

This circuit was found in a 1967 RCA SCR manual. It uses period components that can be replaced with modern equivalents.

Frequency meter (CB7383E)
Found in a Popular Electronics from the 90s, this circuit reaches 100 kHz and battery power is...
LDO 5 A TTL (CB19834E)
This high current regulator with low voltage drop was found in the datasheet of the used...
20 W BTL Automotive Amplifier TDA2005S (CB15241E)
This circuit has a gain of 34 dB and a good power to be used as an audio booster in cars. The...