How to build Electronic Selector for 10 sources with Display-Relay Drive

Description

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

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

Source: http://www.hqew.net/circuit-diagram/How-to-build-Electronic-Selector-for-10-sources-with-Display$2dRelay-Drive_5985.html