Found in a Popular Electronics from the 90s, this shield is activated by a 20 mA current. The inverter is an Open Collector TTL type. The power is 5 V.
Found in Popular Electronics from the 90s, this circuit generates signals in a frequency range set to...
This circuit provides 6.3V of output from a 9V input. The circuit was found in a Dutch publication from...
Based on operational amplifiers of the time, this circuit from the 1980s has high input impedance. The...