Telephone "buzzer" or "Rattler"

[markosjal]

I recently acquired a decorator telephone and encountered a curiosity.

It was a buzzer

At first I removed it from the phone and assumed it to be bad or that it was perhaps a DC Buzzer. The Phone itself contained what appears to be a WE/NE/SC network labelled 4010BNET which is apparently the smaller (newer) of the units fount in Princess phones. There is a .47 mF capacitor in series with this buzzer so I knew it was not DC but oddly enough that is the typical value of a ringer capacitor. I connected the capacitor and buzzer across the line and called it it buzzed (or more like rattled slightly). Recognizing that the capacitor in series also had been in parallel with points A and K on the 4010BNET I tried a .33mf capacitor parallel with te .47 mF and sure enough it rattled louder.

This lead me to check the hookswitch contacts which resembles more of a princess set of contacts as well with a modified plunger arrangement. (maybe like the ATC Mickey/Snoopy with WE guts???), which surely enough the contacts were way out of whack.

So my question really is why would a phone have a barely audible buzzer installed?

Do points A and K on the 4010BNET have a .47 mF capacitor across them? If not .47 what is the value?

thanks,

Mark

[unbeldi]

The 4010B is equivalent to the 425E.

BSP 501-135-100 Issue 4 (Oct 1980) "Networks" lists and compares networks.

I don't know why you state "sure enough it rattled louder" as if it is expected.  You have to examine this buzzer for its properties, before you can make such assumptions.  If it is an A.C. buzzer it should operate just fine without a capacitor at all.  Only in that case it would seem logical that a larger capacitor would cause it to buzz louder as the capacitive impedance decreases with capacitor size at any frequency. But you still need the capacitor to prevent DC-shunting the line permanently.  Such buzzers do not operate resonantly like a telephone ringer. Typical telephone ringers, OTH, usually need the capacitor to create the electrical resonance to match the ringing frequency to transfer enough power into the mechanical parts to cause ringing.  Buzzers usually draw a lot more current than telephonic ringers, because they don't operate resonantly.

A DC buzzer has a break contact that operates with the operation of the clapper, which makes it easy to distinguish them from pure AC buzzers.  Many buzzers for switchboards could be operated both ways, with AC or DC, by using different terminals on the buzzer.

[markosjal]

The 4010B is equivalent to the 425E.

BSP 501-135-100 Issue 4 (Oct 1980) "Networks" lists and compares networks.

I don't know why you state "sure enough it rattled louder" as if it is expected.... 

Yes I see that BSP 501-135-100 Issue 4 (Oct 1980)  confirms it is in fact a capacitor however does not answer my question still. That is if that is the ringer cap and its value. .47mf??

I am trying to get this buzzer back to its original "buzz level" and if that is a .47mf then there are 2 .47 mf caps in parallel both in series with the ringer, thus my comment was "louder as expected"

You sound kind of like you are being an ass or you do not like my post and unsure as to WHY.

Please be nice.

[Alex G. Bell]

Yes I see that BSP 501-135-100 Issue 4 (Oct 1980)  confirms it is in fact a capacitor however does not answer my question still. That is if that is the ringer cap and its value. .47mf??

I am trying to get this buzzer back to its original "buzz level" and if that is a .47mf then there are 2 .47 mf caps in parallel both in series with the ringer, thus my comment was "louder as expected"

You sound kind of like you are being an ass or you do not like my post and unsure as to WHY.

Please be nice.

It would be helpful if you posted a photo of the buzzer.  Small compact buzzers intended for use in association with a phone were small cylindrical devices, about 3/4" dia. and 3//4" high with a mounting tab at the base and screw in the center of the disk which vibrates when operating.  The screw can be turned to adjust the space between the disk and body, which is part of the magnetic circuit thus it affects sound and sensitivity.  To the best of my recollection buzzers of this kind have a neon lamp built into the connecting leads instead of a capacitor.  Suttle and Edwards both made this style.  Not sure they both made a high Z version intended for ringing current.

But since we don't know what kind of buzzer you have this may or may not be relevant.  As usual a picture cuts to the chase and avoids the need for guessing and avoidable words.

[Alex G. Bell]

A DC buzzer has a break contact that operates with the operation of the clapper, which makes it easy to distinguish them from pure AC buzzers.  Many buzzers for switchboards could be operated both ways, with AC or DC, by using different terminals on the buzzer.

Not quite.  Most switchboard buzzers are modifications of the B-type ringer motor or earlier ringer structures and are AC only.  Even the #4 buzzer used in 506 cordless PBXs are high voltage AC-only buzzers although they do not contain a permanent magnet so the armature operates at 40Hz instead of 20Hz.

The only AC/DC buzzers (and single gong bells) were the #7 type primarily used in key telephone systems or intercom adjuncts in "wiring plans" (slightly more complex customer arrangements but without any hold or lamp features), but not in switchboards, and to in lesser quantities as equipment alarm bells in SXS dial PBXs. 

The 7A-7F are rated from 6-48VDC depending on the suffix letter and for higher 60Hz AC voltages due to the inductance limiting AC current to a lower value than DC, but not for 20 or 30Hz ringing current.  They're shown in a broad range of WECo catalogs and in BSPs.

[unbeldi]

Not quite.  Most switchboard buzzers are modifications of the B-type ringer motor or earlier ringer structures and are AC only.  Even the #4 buzzer used in 506 cordless PBXs are high voltage AC-only buzzers although they do not contain a permanent magnet so the armature operates at 40Hz instead of 20Hz.

....

That applies only to WECo buzzers, perhaps. I certainly have switchboard buzzers, for example by Kellogg, that can be used for AC or DC for operation off the talk battery or the ringing supply.  We have no information what kind of buzzer is used here, or whether it even is a telephonic device.

[unbeldi]

Yes I see that BSP 501-135-100 Issue 4 (Oct 1980)  confirms it is in fact a capacitor however does not answer my question still. That is if that is the ringer cap and its value. .47mf??

I am trying to get this buzzer back to its original "buzz level" and if that is a .47mf then there are 2 .47 mf caps in parallel both in series with the ringer, thus my comment was "louder as expected"

You sound kind of like you are being an ass or you do not like my post and unsure as to WHY.

Please be nice.

Watch your language, if you want to insult, then don't expect any answers anymore in the future.

Is the statement of equivalence not enough ?

[Alex G. Bell]

That applies only to WECo buzzers, perhaps. I certainly have switchboard buzzers, for example by Kellogg, that can be used for AC or DC for operation off the talk battery or the ringing supply.  We have no information what kind of buzzer is used here, or whether it even is a telephonic device.

Point taken about Kellogg buzzers.  I don't have the time to research that.

It's unlikely any non-telephonic buzzer would have high enough impedance to operate from ringing current with .45-1.0uF in series.  Most are for 24V or less and require far too much current.  Commercial (non-telephony) buzzers usually are intended for operation on Class 2 (low voltage) wiring.

[markosjal]

Watch your language, if you want to insult, then don't expect any answers anymore in the future.

Is the statement of equivalence not enough ?

I have no clue what "statement of equivalence" you refer to. My original question was the VALUE of the capacitor between A and K  and the value was found nowhere in the document you suggested.

"please be nice" is what I suggested to you. Not sure what problem you have with my post but in the future if you do not like my post please abstain from replying. Nobody is obligating you. Please lighten up on me , yes I called you an ass and I still would because I posted my test and you seem to act as if I was somehow being an idiot.

[markosjal]

That applies only to WECo buzzers, perhaps. I certainly have switchboard buzzers, for example by Kellogg, that can be used for AC or DC for operation off the talk battery or the ringing supply.  We have no information what kind of buzzer is used here, or whether it even is a telephonic device.

HMMMM Was only factory mounted in a phone. I would say that qualifies as a "telephone buzzer"

[markosjal]

Here is the buzzer

Again there is a .47uf connected in series and then the .47uf cap was connected across the A and K terminals so not sure but I think that is another .47uf cap  , so two caps in parallel were in series with buzzer.

[Alex G. Bell]

I see no contacts therefore it must be an AC buzzer.  Is it a high voltage (low current) AC buzzer intended for ringing current or low voltage (high current) AC buzzer intended for power line frequency operation?  You will have to measure the resistance to find out.