Project files: Universal selectors (part 2)

This is the second part of my ”universal selector” series (the first one is here). This post includes the control boards designed to match the selector boards from the first post.

What is it?
Control boards for the relay-based selectors. The download file consists of three designs:

  • A “push-button” input selector based on the 4017 counter IC. This is more or less the same circuit as the selector-part of the ICE-int PCB.
  • A PCB for a rotary-switch based selector.
  • A simple PCB for a 4-LED input indicator that can be used with the above boards.

The last two boards are also suitable as “companions” for the ICE-int board.

How big are the boards?
The board sizes are as follows:

  • The 4017 button switch board measures 1.35″ x 1.35″ (app. 34 x 34 mm.)
  • The rotary switch board measures 2.0″ x 1.25″ (app. 51 x 32 mm.)
  • The LED indicator board measures 0.6″ x 1.3″ (app. 15 x 33 mm.)

What is the status of the boards?
The switch PCBs are both v1.5 because they are existing designs that I have revised to match the standard pinout for the selector boards. The LED PCB is v1.0 because I only realised I needed it after putting everything else together 😉

Does it use any special/expensive/hard-to-find parts?
Nothing that’s worthy of any real concern: The rotary switch is a standard 3pole/4position rotary switch which is made by many different manufacturers (Lorlin, C&K etc.). I’ve tried a few and some seem to fit the PCB a little better than others but with a bit of lead-bending they should all work.

Anything else I need to know?
Some quick notes:

  • The connections between the boards carry power as well so under normal circumstances these boards do not need their own PSU (power is applied via the relay board).
  • 4017 PCB: This is basically the control circuit from the ICE-int PCB, separated from its companions and “spiced up” a bit. The selection is performed by operating the 4017 as a counter, triggered via a debounced mechanical switch. The “spice” consists mostly of a second control input via a PC817 optocoupler which can be connected to a microcontroller port if that suits the application better than a manual switch. The optocoupler then acts as a level shifter making it independent of the relay voltage.
    Most versions of the 4017 will run on power from app. 3V-18V, so as long as relay voltages are within that range it should be fine. For 24V relays, there is a resistor on the board that can be used to drop the supply voltage to within a safe range for the 4017. For 48V relays this solution isn’t really practical and the rotary switch selector should be used instead.
  • Switch board: The switch PCB uses two of the three decks of the switch. One side can be powered externally so it is e.g. possible to use 24V/48V relays and then a separate supply for the LED board which prevents having to drop a lot of power in the LED resistors. If you want to connect the two sides and use a single supply from the relay board, use the jumpers marked JG (for GND) and JV (for V+).
  • LED-board: The “normal” board has separate resistors for each LED so you can use different LED colours if needed. A simpler version with just one resistor is also included. The two boards are mechanically identical and made so they can be mounted vertically on a 1U enclosure front panel. The LEDs are spaced 0.35″ (9mm) apart and the mounting holes are 1″ (25.4 mm.) apart. The offset between the center lines of the LEDs and the center line for the mounting holes is 0.275″ (7mm.).

Download design files here

Related information:
Note: Always read the “intro post” for additional important information about my designs.

One Response to Project files: Universal selectors (part 2)

  1. ksjung88 says:

    Thanks for sharing.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: