Ambient light indicator (CB21567E)

This circuit uses an LDR as a sensor to trigger an LED indicator at a preset lighting level. The power supply does not have to be symmetrical.

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Scale Adapter for Multimeter (CB16845E)
The purpose of this circuit is to allow common analog multimeters to measure low resistances, on...
Analog Multimeter N 201 (CB18869E)
This is the circuit of the N-201 commercial multimeter of the analog type. The circuit is from...
Single transistor receiver (CB22568E)
This receiver was found in the Radio Electronics magazine of March 1953. It tunes to the medium wave...