geoff004
Well-known member
A while back in the PM660 thread member 'codered' mentioned these cheap rotary switches:
http://www.electronicsurplus.com/commerce/catalog/product.jsp?product_id=74532&czuid=1214944002403
At $6 a piece I couldn't pass them up for my PM660 project - so I ordered a bunch and got them today.
They are 18 position, but 1 position is an 'off' position with no contact. These are also 'shorting' switches. Here's how I modified them to suit my needs:
here's the stock unit:
The 18th position, where there is no contact point, is where I put a stopper. There is a small hole there already. I open it up with a small drill bit and put in a screw.
Screw installed
Now I reassemble the switch. I put the deck with the stopper on first. You can kinda make out the screw thread - the head is on the back side of the deck next to that long screw that holds the whole thing together. Also make sure that of the brown spacers, the short ones are in the middle position - they go on after that first deck.
Once it's all together make sure both decks are aligned together. Then with a cutting disk on my dremel I cut off the extra length on the inside shaft and put a slot in the end of both shafts.
Finally I pop the balls from the inner switch to reduce extra friction - that would be the bottom deck. I do this because my knob is only really attached to the outer shaft - I want the inner shaft to follow without any extra force.
Now all you do is take a small flat piece of metal and stick it in the slot before putting on the knob of your choice.
This whole process can easily be done in under 10 minutes.
It's not a 24 position Elma, but it beats a 10 or 12 position switch, and for $6 how can you lose?
[hopefully I corrected the terminology]
http://www.electronicsurplus.com/commerce/catalog/product.jsp?product_id=74532&czuid=1214944002403
At $6 a piece I couldn't pass them up for my PM660 project - so I ordered a bunch and got them today.
They are 18 position, but 1 position is an 'off' position with no contact. These are also 'shorting' switches. Here's how I modified them to suit my needs:
here's the stock unit:
The 18th position, where there is no contact point, is where I put a stopper. There is a small hole there already. I open it up with a small drill bit and put in a screw.
Screw installed
Now I reassemble the switch. I put the deck with the stopper on first. You can kinda make out the screw thread - the head is on the back side of the deck next to that long screw that holds the whole thing together. Also make sure that of the brown spacers, the short ones are in the middle position - they go on after that first deck.
Once it's all together make sure both decks are aligned together. Then with a cutting disk on my dremel I cut off the extra length on the inside shaft and put a slot in the end of both shafts.
Finally I pop the balls from the inner switch to reduce extra friction - that would be the bottom deck. I do this because my knob is only really attached to the outer shaft - I want the inner shaft to follow without any extra force.
Now all you do is take a small flat piece of metal and stick it in the slot before putting on the knob of your choice.
This whole process can easily be done in under 10 minutes.
It's not a 24 position Elma, but it beats a 10 or 12 position switch, and for $6 how can you lose?
[hopefully I corrected the terminology]
