The Elect. Sel. 8 is a simple circuit, with a choice of 8 sources of any sort ,of 8 independent switches. Each switch corresponding with a relay for example the switch S1 activates the RL1 e.t.c. The uses of the circuit are quite a few, choice of entrances in a sound amplifier, choice of command, in a digital circuit etc. In each entrance a LED which may be independent, except if switches with led are used.
R1-8=10Kohms IC1=74LS374 D1-8=Led 3mm
R9=470 ohms IC2=74LS27 C1-3=47nF 63V MKT
R10-17= 4.7Kohms IC3=74LS10 RL1-8= 6-12V DC Relay
TR1=4.7Kohms Trimmer T1-8=BC550 S1-8=Push button SW