Old Ringer Capacitor Value needed

[markosjal]

I bought this ringer on ebay


I am trying to get it to ring but have tried three different ring capaitors (values not known) and can get only a mild rattling sound wen ringing frm my ATA .


What is the normal or best capacitor value to use with this ringer?
It looks like I have about 50 ohms per coil resistance,  100 ohms resistance in total.

[countryman]

No picture displayed here. But a total of 100 Ohms is very low for a regular AC ringer.

[markosjal]

sorry, my bad , I forgot attachment, it is there now.

This is the Capacitor that makes it "tinkle" , but I tried three ringer caps in total an this is the only one that makes it tinkle. I suspect the others wer .33uf and .47mf but not sure of the values. I am even less sure of the value of this one , I think it came from older Stromberg Carlson but not sure of that either.

[RB]

How did you measure/arrive at 50 ohms per coil?

[markosjal]

Digital MultiMeter

[Jack Ryan]

If it is really a 100 ohm ringer, it is too low. They haven't been that low since they used to be in series with other phones on the line.

You might try a 1 or 2k (OK, 1k8 or 2k7) resistor in series. From the original image of the ringer, the gongs are too far apart. They need to be closer so the clapper doesn't get puffed out running between them.

Was there anything else connected when you measured the resistance of the coils?

Jack

[HowardPgh]

What was the meter dial set at?  If it was at R X 10 it would be 500 ohm/coil.

[Babybearjs]

always start with a .47uf capacitor, and go up from there.... tuning the bells also helps once you get it working...

[dsk]

The REN load of a ringer like that may be extreme, and not good for the ATA. 
A transformer may solve it.  Typical a small transformer about 110-24V could be tried.

dsk

[tubaman]

I too would be surprised if it's 50 ohms per coil - the lowest I've come across is 150 per coil on a local battery set.
Also, the gongs look way too far apart for it to work well. Have you tried moving them closer together?

[dsk]

It may absolutely be a possibility that the meter readings are wrong. At such lo resistance a 9V battery that are held on the wires, turned and held again should cause a pretty strong hammering making a gong each time.  I have an old magneto set with 300 ohms ringer, and have to make a little dugout in the basement to see if it even could be lower resistance on an old ringer.  Mechanichal tuning and moving the bells are always a good idea on such old ringers.   My oldest CB phone has 2 uF capacitor and 400 ohms ringer.  I had to reduce that capacitor to get it OK on my ATA, and it works well with 1 uF.
A modern ringer will have a load not far from 4000 ohms + a cap.   To make a transformer matching that will be difficult.  When I suggested a 110-24V it was because it should do , and that will compensate for a loss.  Transformers made for  50 or 60 Hz are not good for 20Hz.
If you just want something simple a cap of max 1 uf may do, but the calculations of such things are extremely complex.  Test and fail may be the easiest solution, The smaller cap that makes it work, the lower REN load. Resistors are not a good idea since they cause a loss that just ends up as heat. 

[markosjal]

These gongs are not adjustable. The holes in te gongs are on centers and the posts they mount on are fixed as well. I was thinking of using a rubber mallot to bang them closer together.

I will re-check resistance once I pull this phone out of storage agan.

[countryman]

It might be deceiving but it looks like the posts are bent outwards. I would not use a mallet though but take the gongs off and straighten the posts with pliers or a vice.

[dsk]

I agree in what countryman says about bending, and it may be to small gongs unoriginal ??

I dug out an old ringer, and measured 118 ohms between the terminals. The ringer moves from side to side when I apply 3V or more.

Connected to 70V 20Hz it rang barely hear-able with a 0.47uF capacitor, much better with 1uF.  Did not test more than that but it strengthens my idea about a transformer, maybe from an old "battery eliminator" rated around 6watts.

dsk

[dsk]

Did some testing and measuring, my ringer in series with 1 uF had a impedance of approx  (All numbers are what I measured and should not be deeemed to be more accurate than +/- 10%) 8333ohms or 0.84 REN
I had a transformer made for 20 Hz with windingratio 6:1 and that made the rining much loader, and the REN increased to 1.12  With a tranformer from an old adapter with ratio 18:1 the same load ringing and REN at 1.10.  Tried a third transvormer pretty equal to the last, no ringing at all...

dsk