Found in a 1967 Electronics World, this preamplifier uses an integrated circuit from that time, difficult to obtain today. The maximum frequency is 15 kHz.
This circuit can be used as an optical switch or photosensor to excite TTL logic. The transistor can be...
This circuit was found in a Popular Electronics of the 90s. The output amplitude will be between...
This 80's Exar circuit has a carrier detector for frequencies up to 500 kHz. The circuit uses a...