SP Multiple Throw relay?

The old pulse dial telephone did their job by pulsing stepper relays back a the telephone office. You might do a search for [stepper relay]. But I think 10 (or maybe 11, a start position and 10 other positions for the 10 digits) throw are a lot more common than 12. But that is an opinion based on ignorance.

What behavior are you looking for? The stepper relay that John is talking about moves to another contact each time an input is pulsed, and must have a way of resetting the thing back to zero (presumably with a second input). Is that what you want, or do you want something like a 4- wire system that selects one of 12 contacts, only for as long as power is applied?

HOW MUCH **CURRENT**?

you mean like a stepping relay?

Bob

Here's on that's available on ebay. The search term was "strowger".

Bob

--- Ledex and Oak used to make motorized switches using rotary solenoids, and they can be had surplus nowadays.

Google "LEDEX switch" for quite a few hits.

If you don't want to go that route it's easy enough to build one using logic and discrete relays.

What's your application?

-- JF

I have seen and held in my hand stepper relays with 50 positions and 10 rows of contacts. But that was 25 years ago.

-- but if you want it to remember it's state like a stepping relay, you have to supply power to the microcontroller.

This is probably the right answer, but the OP has to cough up some more information before it's clear.

Hunt around for 'rotary stepping switch' or 'motorized switch'

You can find a few examples here:

I suppose, if you can't find exactly the switch you need, you could build your own motorized switch, using a dual-pole, 12 position switch. You'd use one pole for your 120 VAC switching, and the other pole for indexing the motor drive.

Good luck!

Tom

Ha, We still maintain an old HIPOT test cage at work that uses 2 8 Position stepper single pole relay. The two formed as a matrix to select 1 out of the possible 255 leads in the cage. One Selects the low ROW while the other selects The High COL scan to select the proper vacuumed relay when connecting a lead wire. The machine has a mechanical timer, lead down counter, paper printer etc.. very old but still working.

Thanks everybody for your advice. Folks here are _really_ smart!

Turns out I was thinking about it wrong, and indeed all I needed to do was learn to think of the problem in a matrix. I've got a lot to learn.

Thanks again for the help!

cheers dafydd

...and the rather elegant row/column solution was the famous Cunningham Crossbar.

Use latching relays. During the 'step' pulse the uc wakes up, senses the current position or reads it from eeprom, changes the relays as appropriate and loses power. With a suitable cap and the biultin brownout detection in most modern micros you can ensure that pulses are either ignored or result in one complete step.