This shield circuit is from a 1968s Motorola documentation. The relay is according to the supply voltage. R1 can be reduced to lower trigger voltages.
Figure bellow shows how the 4510, a divide-by-1U, up/down counter with three-state outputs is...
This circuit was obtained from the Radio Electronics magazine of April 1991. The circuit is based...
This digital signal attenuator was found in a 90s Electronic Design. The circuit operates at...