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We found this circuit in the November 1992 issue of Radio Electronics magazine. The 30V power supply must be symmetrical and preamplification stages are included.
This circuit uses an LDR as a sensor to trigger an LED indicator at a preset lighting level. The...
We found this circuit in an American publication from the 80's translated into Portuguese. The...
We found this circuit in an old French documentation from the 70s, but it can be assembled using...