sundance-communications.com/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems A & K network terminal designations

Quick question, I know A and K have the ringer capacitor across them. Does A = anode, and k = kathode since the capacitor must be electrolytic.

No, those terminal designations have nothing to do with the capacitor itself. I assure you that it is a non-polarized capacitor that is used to block the flow of DC through the ringer coil. They just had to give the terminals names so that wiring diagrams would make sense.

If you think about it, the incoming Tip and Ring are on terminals C and RR. Those sure don't make any sense either.

I was just about to post that upon reflection, it was a stupid question, sigh!

You're right about the designation they gave. Make no sense at all!

Ed, what's the frequency of the AC voltage that rings...the ringer!?

So as far as the capacitor is concerned, it's used to block the -48VDC?

20hz and I'd say yes.

Thanks Bill! My ringer coil has an extra pair of leads on it. If I connected them in reverse order from the coils first pair, would I have continious ringing?

No. The interrupted ringing is controlled by the source. The ringer only responds to the cadence of the ringing voltage being sent to it.

Yes, the capacitor is intended to block 48 VDC from flowing through the ringer's coil. If the capacitor wasn't there, the coil would essentially place a short circuit on the line and cause it to stay off-hook.

Most ringer coils you will encounter actually consist of two coils wrapped around a common core. The black and slate leads are from one coil (1,000 ohms). The red and slate/red leads are from the other coil (2,650 ohms). The capacitor connects between the two coil windings, although it can be placed anywhere in the circuit.

Many newer coils only have red and black leads. This is because there is little likelihood that the separate coils will ever be necessary again. These were used back in the days of party lines to allow different ringers to operate on the same line with different resistances and capacitance. This is a very simplistic description of their purpose, but don't waste too much time pondering that old technology.

My reasoning was this: Ring on my phone is connected to A, and the red lead from the ringer coil is connected to K, thus the AC ringing voltage passes through the capacitor on its way to the coil.

The black lead from the ringer coil is simultaneously connected with tip and a hook switch lead which "makes" when the phone is off hook.

Normally, the discharging coil discharges through tip in my setup (I could be wrong).

I was thinking if I could channel the voltage of the discharging coil BACK into the coil via the other two leads (red slate/red), then I could get constant ring.

I know the AC signal coming from the source is in bursts.

Anyway, the technology may be redundant, but its simplicity makes learning the fundamentals easier.

You are using the red and black as the ends of each coil, but the capacitor is connected between the other ends of them (slate and slate/red).

You could probably use one coil or another to experiment, but you'd need a jumper wire of some sort for the final connection:

1,000 ohm:

Black to L1
Slate to A
Jumper between K and L2

2,650 ohm:

Red to L2
Slate/red to A
Jumper between K and L1

3,650 ohm (normal):

Red to L2
Black to L1
Slate to K
Slate/red to A

I don't think that you'll get much difference in the response by only using one coil, but it won't hurt anything to try.

Note: I'm not positive if the resistance values I've indicated are accurate. It has been a long time since I've messed with the separate coils. Maybe one of the other guys will chime in if I'm incorrect.

Just edited my previous post. Thanks for all the help Ed. Now I must sleep!