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.
This TTL divider divide by 0 to 9 the frequency of a signal applied to its input. Maximum...
Found in the American 73 magazine for radio amateurs, this circuit can test common quartz...
Found in a 1966 General Electric documentation, this circuit controls an incandescent lamp from an...