Author Topic: Blew out Bell?  (Read 2263 times)

Offline jarwulf

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Blew out Bell?
« on: March 09, 2014, 04:10:34 AM »
I've been tinkering around with connections to this P1A? ringer from a candlestick phone





to the poweredsine ringing generator




And suddenly the bell seems to have stopped working in testing.  I tried attaching the bell to a 6v battery and 7v power supply directly to no avail while before it seemed to give weak ring. The only thing I can figure is I attached the wrong blue and white ends to the wrong leads coming from the bell. Or possible didn't use a resistor Otherwise something might be wrong in the attachment to the power supply.

What is the proper connection? The bell has two wires black and red. I assume the blue goes to the red and white goes to the black? Do you think the ringer is FUBAR? HOw could I test? If it is where can I buy a new one?
« Last Edit: March 09, 2014, 04:24:00 AM by jarwulf »

Offline twocvbloke

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Re: Blew out Bell?
« Reply #1 on: March 09, 2014, 04:32:36 AM »
The ringer needs 90v AC at about 20 to 30Hz, a 6v DC battery directly to the bell won't do anything but ruin the magnet built into the ringer as a DC current will produce a solid-on electromagnet, the sort of thing you see lifting scrap metals at a junkyard...

The simplest way to test it is with a line cable and a .47uF capacitor in series connected to a phoneline, phone system or a magneto generator (inside a crank phone or a linesman's test phone), if it rings then, you have a problem with your circuit... :)

And I can see in the diagram you posted that there's no capacitor, which is needed for the ringer to work, again, a .47uF capacitor in series with the ringer will do the job, assuming the coil assembly hasn't been demagnetised from having a DC battery directly connected to it...  :)

Offline jarwulf

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Re: Blew out Bell?
« Reply #2 on: March 09, 2014, 05:10:09 AM »
The ringer needs 90v AC at about 20 to 30Hz, a 6v DC battery directly to the bell won't do anything but ruin the magnet built into the ringer as a DC current will produce a solid-on electromagnet, the sort of thing you see lifting scrap metals at a junkyard...

The simplest way to test it is with a line cable and a .47uF capacitor in series connected to a phoneline, phone system or a magneto generator (inside a crank phone or a linesman's test phone), if it rings then, you have a problem with your circuit... :)

And I can see in the diagram you posted that there's no capacitor, which is needed for the ringer to work, again, a .47uF capacitor in series with the ringer will do the job, assuming the coil assembly hasn't been demagnetised from having a DC battery directly connected to it...  :)

SO you're saying that connecting a battery or PS or the ring generator without a resistor shouldn't harm the ringer? Do you know the proper wiring for the ring generator to the ringer leads?  Is there anyway to 'remagnetize' the thing? As for connecting to the phoneline I'm afraid we're past that stage now. I've removed the network and all the associated wiring. Its just the bell with the two leads sticking out. THe bell has worked as I planned before, its just that its suddenly stopped working now and I don't know why.

Offline dsk

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Re: Blew out Bell?
« Reply #3 on: March 09, 2014, 05:33:26 AM »
I have doorbell setup, push button connects battery to ring generator. The ringer failed until I got a capacitor in series with the ringer.
I have no resistor in my circuit, and do not see any need for that. The ringer was an old 1000 ohms ringer and I 1 uF capacitor was used on these, so just used a 1 uF capacitor, no science in this case.

dsk

Offline twocvbloke

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Re: Blew out Bell?
« Reply #4 on: March 09, 2014, 05:49:37 AM »
SO you're saying that connecting a battery or PS or the ring generator without a resistor shouldn't harm the ringer?

Connecting a DC battery directly to the ringer is not a good idea, regardless of using a resistor, as a DC current is generating a solid magnetic field inside the ringer coil which may act against it's built-in magnet causing it to demagnetise (and remagnetising is not possible with anything you have at home, it needs specialised equipment to do so) and thus weakening or ruining the ringer...

You need an AC supply to make the bell ring (as the AC waveform is what moves the clapper back and forth to repeatedly strike the bell to create the ringing) which is what the PowerDsine unit creates, 12vDC (not 6v or 7v!!) goes in one side (Red and Black to the generator), the electronics inside perform some magic, and then out of the other side (Blue and White) comes as depicted 70vAC at 20Hz, regardless of the colour of the wires, add a 0.47uF capacitor in series and it should work...

As the ringer is an AC device, it doesn't matter which way round the Red and Black wires from the ringer are connected to the blue and white wires form the ring generator, it'll will work whichever way round you wire it...

Quote
As for connecting to the phoneline I'm afraid we're past that stage now.

No we're not, for testing on a phoneline, all you need is the ringer, a 0.47uF capacitor and a line cable, nothing more, no network required, as that is how simple ringer boxes are wired, I built one myself a couple of years back using a C4A ringer from a 500 phone... :)

If the ringer works connected to the phoneline in this manner, then the ringer is fine, if not then something has either gone wrong with the coil, or you have turned down the ringer volume control which has silenced the ringer... :)

Offline dsk

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Re: Blew out Bell?
« Reply #5 on: March 09, 2014, 06:11:29 AM »
I would not worry about a little dc over the ringer. Siemens used a circuit putting the ringer and a 100 ohms resistor in series across the line since 19 twenties until they stopped using mechanical ringers.
dsk

Offline G-Man

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Re: Blew out Bell?
« Reply #6 on: March 09, 2014, 06:55:55 AM »
First, measure the resistance of the ringer’s coils and then measure the input and output voltages of the ringing generator. It should be obvious where the fault is.
 
Connecting the ringer directly to the ringing generator without a capacitor is an accepted practice on key systems and will not harm the ringer.  Still it would be advisable to connect one in series with it.
 
Connecting it directly to a low-voltage dc source should not demagnetize it though for other reasons it should not be applied.
 
The 330-ohm resistor is probably for current-limiting to prevent catastrophic failure in the event the generator’s output subjected to an unacceptable load or is shorted. If you by-passed it then irreparable harm may have occurred if such a fault has occurred.
 
I do not know if this particular model has a reverse polarity diode and if it does not and you happened to transpose the polarity on the generator’s input it possibly could burn-out critical components.
 
Applying a lower voltage to its input is not a good idea either.
 
The best practice would be to follow the manufacturer’s simple instructions in these areas and not to improvise.

Offline poplar1

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Re: Blew out Bell?
« Reply #7 on: March 09, 2014, 07:19:08 AM »
If you are looking for a 0.47 uF capacitor, there is one in the network between terminals A and K.
"C'est pas une restauration, c'est une rénovation."--François Martin.

Offline G-Man

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Re: Blew out Bell?
« Reply #8 on: March 09, 2014, 07:37:27 AM »
 The good news is that there is a BUY IT NOW auction on eBay that is selling a similar model in lots of two for $9.90.



 [/font]Part : PCR-SIN03V12F20-C
 
 Mfr.: PowerDsine
 
 Description: RINGING GENERATOR 12VDC TO 70 Vrms 20Hz

(Title says Mhz by mistake. It is 20-Hz-)
 2Pcs Lot
 Item weight: 43gr

Offline G-Man

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Re: Blew out Bell?
« Reply #9 on: March 09, 2014, 07:39:12 AM »
It would help if I included the eBay link:

http://www.ebay.com/itm/PowerDsine-PCR-SIN03V12F20-C-RINGING-GENERATOR-12VDC-TO-70V-20MHz-2Pcs-Lot-/121058890727



The good news is that there is a BUY IT NOW auction on eBay that is selling a similar model in lots of two for $9.90.



 [/font]Part : PCR-SIN03V12F20-C
 
 Mfr.: PowerDsine
 
 Description: RINGING GENERATOR 12VDC TO 70 Vrms 20Hz

(Title says Mhz by mistake. It is 20-Hz-)
 2Pcs Lot
 Item weight: 43gr

« Last Edit: March 09, 2014, 07:53:01 AM by TelePlay »

Offline dsk

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Re: Blew out Bell?
« Reply #10 on: March 09, 2014, 08:06:53 AM »
That is the same as I use in my door bell system.

dsk

Offline DavePEI

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Re: Blew out Bell?
« Reply #11 on: March 09, 2014, 09:16:00 AM »
The 330-ohm resistor is probably for current-limiting to prevent catastrophic failure in the event the generator’s output subjected to an unacceptable load or is shorted. If you by-passed it then irreparable harm may have occurred if such a fault has occurred
That is exactly why the resistor is there - to protect the generator against shorts which, without the resistor can blow out the generator. Basically, it guarantees a load within the acceptable range. Its not just there to look pretty! :)

Dave
« Last Edit: March 09, 2014, 10:15:25 AM by DavePEI »
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