Suggested by an American publication of 1964 this circuit is intended for the capture of signals from film tracks recorded by optical systems, common at the time.
This protector was found in an Electronics Now from the 90s. The 250 V transient suppressors are common...
Based on an LM36000 OTA this circuit was found in the July 1988 issue of Radio Electronics...
This circuit only works with incandescent lamps and the frequency is adjusted in the pot,...