BS2 telephone ringer

bddbbd.b

Does anyone have any eperience with interfacing the BS2 with a Bell 2500 DTMF telephone (the classic desk phone seen in hotels and warehouses around the US). I have schematics and code for hooking it up to dial out, but I need to make the phone ring while it is dialing out. The best solution would be a simple relay that triggers the ringer or something along those lines, but if the only solution is a separate ringer circuit not actually attached to the phone line, so be it.
thanks,
bd

Franklin

bddbbd.b·said...
but I need to make the phone ring while it is dialing out

Not sure what you mean. Do you want it to make noise if somebody tries to use it?

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- Stephen

Mike Green

You'll probably be better off with a separate ringer. The POTS (Plain Old Telephone System) ringer requires around 90 VAC to be placed on the phone line. There's not much of a problem switching the 90VAC with a relay. The issue is the source of the 90VAC. It needs to be provided somehow or generated.

bddbbd.b

to clarify the desired function: the phone will be dialing out, with the handset still in the cradle, but technically off the hook by relay attached to stamp. It needs to be ringing on both ends at the same time, until someone picks it up, as expected. That is, it needs to ring on both sides until both sides answer, or one side hangs up.

Mike- do you have, or know where to find a schematic to set up the separate ringer? it wouldn't work just to hook the ringer's coil up directly to 90VAC (through a relay), right?

Mike Green

Here's a nice summary I found with a web search www.tkk.fi/Misc/Electronics/circuits/telephone_ringer.html