Frequency meter (CB7485E)

Found in a 1960 Sylvania manual, this circuit is intended to measure audio signals frequency. Transistors support modern equivalents.

Negative Feedback Stage (CB6131E)
This circuit is from a 1967 US publication. The configuration can serve as a basis for designs...
Field strength meter (CB8220E)
This passive tuned circuit was found in a 90s Popular Electronics. The coils must be according to the...
Temperature Compensated Crystal Oscillator (CB6144E)
This circuit was obtained from Linear Technology documentation from the 80's. Powered by 5 V it...