We found this circuit in a Radio Electronics from October 1963. The circuit uses an output transformer with a center tap. The trimpot is adjusted for higher gain and lower quiescent current.
This common configuration source with diode bridge and single winding transformer was found in a...
This 2009 circuit is a bilateral call warning. Easy to build, using light communication between two...
This circuit was found in a 90s Popular Electronics. The integrated circuit used is similar to the 741....