Published in a PE Hobbyst Handbook of 1991, this sensor uses an integrated circuit that is unusual today. The circuit is based on a high frequency oscillator.
This Radio Electronics circuit, in an 80's edition, decodes the 67 kHz signal used at the time to...
This circuit was found in a 1966 General Electric documentation. The circuit makes use of PUTs...
This circuit was found in an old Electronic Design. It makes use of sidacs and operational not very...