Morse key switch

If you have more than one rig or use a couple of paddles/keys and are fed up of fiddling with leads to switch between them then this may be a project you fancy.

(There is a prize for spotting the deliberate mistake on the label)

The circuit is just a switching matrix consisting of:

• 8 off 3.5 mm stereo sockets (Bitsbox CN070 £0.32)

• 2 off 3 pole 4 way rotary switches (Bitsbox SW079 £1.49)

• 1 off Plastic project box (Bitsbox EN002 £1.99 - larger than the one I used which was 90 x 60 x 40 but more room might be a good idea!)

• 2 off knobs

Total cost then is £7.53 and with £1.75 postage then we are still less than a tenner! As an aside I have no affiliation with Bitsbox other than being a satisfied customer and wanting to pass on the savings, especially in postage and wanting to support decent electronics suppliers.

The circuit is simple:

To accommodate paddles we need 3 wires so stereo connectors with tip, ring and sleeve are required. We want to connect the tip, ring and sleeve of the selected input to the tip, ring and sleeve of the selected output.

If you have never used a rotary switch before, the poles are in the middle circle and the 'ways' are around the outside of the switch. Each pole will have 4 corresponding 'ways'. Looking at the circuit you can see that S1 has 3 poles and each of these has 4 'ways'.

In the position shown S1 is connecting Tip 1, Ring 1 and Sleeve 1 to S2' Poles on the right. If we move S1 to the next position it connects Tip 2, Ring 2 and Sleeve 2 to S2 and so on. S2 does the reverse and allows you to select which output the selected input should follow.

Construction is pretty easy but again the 'measure twice cut once' rule applies and I created a drilling template for my box which made things a lot easier. I pre-wired all the switches and mounted them in the case, I then put the first row of sockets in (outputs in my case) and soldered them according to the circuit trying to make as neat a job as I could (not very well).

Then I added the inputs and soldered the remaining connections to end up like this...

Yes - a rat's nest if ever there was one!

Not a great fan of labelling - Tippex and a pen did it for me....

So does it work - as expected, I can switch my Kent, Bencher and straight key between the IC-718 and SS105 with no effort at all - result.