Wiring Experts Chime In: Ring Supply 551A

[ramegoom]

Hoping to get someone out there to confirm that I'm doing this correctly. I have a 551A switchboard that I'm attempting to add a 30Hz power supply to produce a ring signal. I *think* I have the right tie-in location but want to be sure. The schematic is not very specific. In the red circle is where I believe the AC supply should be attached, but need verification.

Anyone?

Thanks!

[trainman]

Schematically it looks correct. On your terminal board in the back, it should say Ring, and the terminal numbers should match the schematic.

[ramegoom]

Sounds like a plan. There is a switch on the front panel of the switchboard where you can choose either the CRANK or EXTERNAL source, and there is a light bulb in series with it, so I figure it's got to be those two terminals on the MISC terminal block. Just don't want to pour AC into something that can't handle the power.

Almost ready to test this beast.

[trainman]

The bulb is a ballast bulb. It is in the ringer circuit. Its basically overload protection. As more current is drawn, the bulb will start to grow brighter. If there is a short circuit, the bulb will light to full brightness and eventually burn out.