Multi-pulse trigger (CB21477E)

This circuit was found in a 1967 EEE. The transistors are from the time and can be tested equivalent.

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Telephone dialer (CB9235E)
This circuit was obtained in Radio Electronics from the 90s. The integrated circuit is uncommon...
10 Hour Digital Clock (CB17007E)
This 4-digit digital clock for hours and minutes with CMOS integrated circuits was found in a 1995...
Preamplifier for Microphone (MSB062E)
This circuit is indicated to operation with low intensity sources such as electret microphones and...