atcomsystems.ca/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems Latching relays

Did you guys have a specific type of latching relay to use for controlling off/on states from either a momentary key or an intercom buzzer input?

I have a couple things I would like to control using the unused extra station outputs on my Melco intercom that is using LB buzzers.

Of course I could get new relays from mouser or digikey but I was curious if there were WE, Melco or other type specifically designed for telco installation that might look more at home on my backboard.

The 237B (1A1) KTU was perfect for this application. Although it was officially branded as an add-on conference unit to tie two pre-determined lines together for conference calling, there's no reason why the many NC and NO contacts provided can't be used for any purpose. The original circuit design provided for it to be controlled by the A lead of a non-locking key (basically a momentary ground) to activate or de-activate the latching circuit.

We often used these KTUs for a night service or ring transfer button on the attendant's 1A2 phone, rather than those silly TKM side car switches. With all of the available relay contacts, we could even use this KTU to busy out the lines in hunt on small systems if needed.

You could certainly use a dial intercom code to control one of these, but you'd have to reverse the polarity of the buzzer voltage input to it. Rather than having the intercom switch the +/-10VAC battery, you'd have it switch the ground and have the battery voltage standing on the other side of the buzzers. All packaged intercom units had provisions to allow for this reversal.

Now finding a 237B will be another subject.

Thanks Ed, of course it would be hard to find. Why not? Lol
You guys never cease to amaze me with the tricks you pulled off with repurposed parts.

As I recall, there was a latching relay contact on the Melco/ Teltone ICM units. I believe it was designated PC (Page Control) and designed to cut off background music or whatever.

Depending what you want to do that might help.

Or.....

I used to deal with an outfit called Blan Electronics. They had every type of relay known to man (not WECO, but commercial or industrial models). I'm not sure if they're still around (google is a little vague) but their number is/was 212-233-6288.

Sam

That's a good idea Sam I hadn't thought about the page contact. I'll have to look into that a bit more.

While not BSP, and definitely not MilSpec, I like to use Altronix relays (Google "Altronix relay") which are designed for the alarm industry. There is a whole family of relays in 12 and 24 volts, power supplies with or w/o charging capability, and mounting rails and enclosures to make a neat installation.

I have used dial intercom units for controls and have mounted them and these relays in a metal alarm panel box. If you are using a Teltone icm unit, you can use a single code (such as a 5) to operate and latch, and its complementary two-digit code (such as 25) to knock it down.

Or if the device being controlled only needs to be up while the DICM is off-hook (like a paging unit or speaker) you can use the LAMP or other Off Normal lead to hold the relay, so that when you go On Hook, the relay falls.

You can often find Altronix relays on Ebay.

Altronix makes excellent products.
I use their CCTV power supplies on all my installs.
I also use one of their power supplies for the fire alarm pull stations and horn strobes on display in my shop.