Electronic Selector for 10 sources with Display-Relay Drive


This is a circuit for alternative sources selection. It combines mechanical selection using a rotating switch S1, the electronic drive of the relays RL 1-10 and also the optical indication of the selection by the Display DSP1. The function is based on the connection of the mechanical selections into 4 Bit (BCD) code. It is managed by the proper polarization of the diodes D1-10 and simultaneous convention into decimal output by IC2 which is a BCD to decimal decoder. The monitor is driven by the IC1, which is a BCD to 7- segment Latch/ decoder/ driver. We can made a lot of combinations and selections on the circuit. For instance, we may add Led' s in parallel with the RL1-10.

Circuit diagram

Circuit diagram

Part list

  • R1....4= 10Kohms
  • R5....11= 820 ohms
  • R12....21= 15Kohms
  • C1= 100nF 63V MKT
  • C2= 47uF 25V
  • D1.....20= 1N4148
  • IC1= 4511
  • IC2= 4028
  • Q1-10= BD679
  • DSP1= Display 7 segment Common Cathode
  • S1= 1X10 Step Selector
  • RL1....10= 6V or 12V Relay