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Music On Hold... a simple circuit...

Started by Babybearjs, January 04, 2018, 01:58:58 AM

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Babybearjs

OK, Ive asked this before and finally found a simple circuit for what I want. I can build this without any problem, but where would I tie the switch (S1) in to a 1A1 system? and if I wanted to tie into all 4 lines, would I need to have just one unit for all lines or 4 units....
John

compubit

I believe you'd need 4 separate circuits to prevent cross-talk between the lines.

I'm not sure where you'd introduce this into a 1A1 (or 1A2) circuit, but I'd think it would be around the point where the resistance is bridged across the line to keep the line from hanging up.

Most of the circuits I recall from the 80s used a Silicon-controlled Rectifier as part of the circuit along with a momentary switch (vs. a single pole switch like you have in the diagram).   It basically latched the hold circuit until someone picked the phone (or an extension) up drawing enough current to release the "latch" on the hold circuit.

I phone I purchased about a year ago had an external hold button installed - I'll dig it up (when I get home) and see how it was designed...

Jim
A phone phanatic since I was less than 2 (thanks to Fisher Price); collector since a teenager; now able to afford to play!
Favorite Phone: Western Electric Trimline - it just feels right holding it up to my face!

rdelius

On some line cards, there was a MOH jumper and a ground. I used a simalar circuit but had multipal transformers to isolite the circuit boards. otherwise there was a talk path between callers on hold.i did not have a ksu with a MOH buss