Making a telephone ringer

[JimWebber]

Which in a basic form is precisely how the ring cadence used to be generated in each telephone exchange.

In fact the same machine drove different cams on the same shaft which supplied ALL of the different tones as well - dial tone, interrupted dial, busy, equipment busy, ring tone etc etc.

 

Tell me about it!

 

I spent four months as an apprentice in an old Strowger exchange, and the main workbench for repairing selectors and the like was sat right behind said machine......

 

Now all the random clicking and banging from the rest of the exchange did not bother me, but the constant regular "Click" "Click", "Clickety Click" Drove me up the wall!

 

An amazing four months though! What an experience.

 

Jim

[dbuckley]

On-board links choose whether the hook switch disconnects the bell on going off-hook...

Although it appears that is the case from the diagram, that is far from why its like that - back in the day if you had more than one phone in your house / business they were wired according to one of the wiring "plans" so there one a "plan 1" setup, and a "plan 5" and probably more I cant remember, and cant be botherered googling, but there is an excellent BT related site that will doubtless have all the data. But anyway, all the bells in the entire setup were wired in series from a master phone or bell box. The links were so a phone could be reconfigured for this mode where for extension phones the bell and the bell half of the hook switch were connected to an extra pair of wires, and had no other connection to anything inside that phone.

 

...though it may cause a nasty buzzing through the earpiece which may be audible to the audience unless the ringer simulator is turned off manually when they answer.

Not to mention deafening the actor!

 

All decent phone ringers can detect off-hook. Its not that hard, just need a capcitor, an optoisolator and a few bits. Or a couple of the right type of relays.

 

I have an untested design (including PCB layout) of a wireless phone ringer - the board in a standard 760 series phone is replaced by mine (you need tosteal the hook switch as its on the PCB and put it on the new board), wire in the bell, add a tiny RC receiver and a radio control car 7.6V batter pack and voila - a wireless remotely controlled ringable phone. Must finish that off one day...

[KevinE]

Although it appears that is the case from the diagram, that is far from why its like that - back in the day if you had more than one phone in your house / business they were wired according to one of the wiring "plans" so there one a "plan 1" setup, and a "plan 5" and probably more

 

Yep. I mentioned that so that anyone wanting to run the phone on a home made ringer supply could rearrange the links with the aid of the diagram I linked to and stop any weird effects.