I am using this board to pre-select power supply for me garden layout. I primarily use Marklin Digital, but sometimes I also have guest trains running on DC power, also external digital station. One of the 5 inputs will be reouted to the output connection. I have created this board so safely switch up to 10A power to the rails. The rotary selector switches I was able to find in the shops were all rated just for 1-2A.

Please note

• I run this board from 12V, but if you pick different relays you can use lower voltage as well. In that case you need to check the resistors
• There is no polarity protection on the supply input terminal, please double check your connections
• In the schematics, I included 2.2K resistor for the LED, but actually for the LED I picked (random LED from my parts bin), I ended up using a 5K resistor.

BOM

• IC4017 decade counter IC, optional IC socket
• 6pcs 10k resistor
• 5pcs 5k resistor: you may need to pick different values depending on your LED type.
• 5pcs 5mm LED (I used a generic high power white LED)
• 5pcs 1N4004 diode
• 5pcs BD547 transistor
• 7pcs double 5.08mm pitch screw terminals
• Generic push button
• 100nF ceramic capacitor
• 5pcs AZ733W-2A-12DE (12V relay, switching current 10A)