How do I make a telephone ring?

I have a seemingly simple problem that I am stuck with.

We have an office that is detached from a garage. There is currently a phone in both locations as well as a bell that rings when the telephone rings. All three devices (two phones and the ringer) are on the same telephone line. The receptionist would like for the phones to ring but to have the bell on it's own system, away from the telephone system. This way she can answer the phone, and if the call is for someone in the garage she can push a button and make the bell ring to let the mechanics know to pick up the phone.

I am assuming a power supply of some sort (120v ac to 5v dc??) that connects to a button and runs over a wire to the ringer would work. When she presses the button, the 5volts are sent to the ringer and voila, ring ring!

120v===5v===button========ringer

The ringer is a standard telephone device with a red and green connector on it, a ringer (bell), and no way to pick up the line. It simply rings when theline is ringing and stops when it is answered.

Thanks for any help!
Rene

That's basically right, but if the ringer was designed to plug into the phone network, it won't be expecting 5V DC to ring. On the UK phone network it would be 75V AC 25Hz; Wikipedia says the US is 90V AC 20Hz. It'd probably be harder to generate those waveforms, than it would to just buy a non-phone-related bell or buzzer that you could run from normal voltages.

Peter

Commonly refered to as +/- 48V in the industry.

Cheers

Gotcha. The voltage was hiding from me. My Google-Fu is weak today.

I was hoping to use what we have on hand, but I'll look into a remote buzzer of some sort.

Thanks!

A 35-45VDC PSU, a 555 timer, a resistor, capacitor, inverter, and an H-Bridge chip (eg. L293D for 35VDC).

Cheers

Why not just use a common household doorbell and pushbutton? Can't be that expensive or difficult to rig up...

Stig

That's already been suggested earlier. I was just responding to the "I was hoping to use what we have on hand" comment.

Cheers!

I'm thinking that Ma Bell wouldn't like having a ring signal sent back to her. Not at all.

It would have been disconnected from the telephone circuit and wired directly to a power supply and a push button.

Due to Occupational Health and Safety reasons with having wires strung and all associated "risks" and the associated costs to minimize the "risks" we ended up just buying a wireless doorbell.

Thanks for the voltage info though. I was always curious about what was sent over those wires.

Rene

Ok, that makes some sense. You could have even used the spare pair in the wiring to signal the secondary phones.

Stupid steel building! The wireless doorbell won't work through the wall! Looks like we will have to wait until the ground thaws to install conduit between the buildings and make sure all is up to code. Doh!

You just need a better sending unit. This one ought to do the trick.

tanstaafl.

Ordered! Thanks!!

You could try one of these.

No, sounds too dangerous.

The Internal Antenna is a passive device designed to capture stray radiation within the phone and re-radiate the signal to improve the phone's performance.

You'd have to install shielding everywhere and make everybody wear lead-lined underwear to deal with all the RF energy that would be permeating the environment.

tanstaafl.

Gee, I never thought of those boosters. My friend has some that he received with an ebay order a few years ago. I should get them and plaster all over the transmitter. I wonder if they will support the frequency as it is different from the cell frequencies. As for shielding, I don't think I'd have to worry too much. There's only one employee in the receptionist building and that position rotates every few months so they wouldn't be getting a year round dose. The rest of the employees are already in a big steel building.

Reene

Those things do NOTHING, except transfer money from your pocket to someone else's.

I should have put a smile on that. Eh.

Me too...

I was thinking they were both tongue in cheek, but one can never be too sure.