Author Topic: Anyone care to have a Technical descusion about bias springs in ringers?  (Read 191 times)

Offline RB

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I present my WE tin box...not sure of model, not much on it.
It appears to be a form of intercom, as there is no induction coil, and a single spst hook switch.
Anyway, the bell mounts were pretty banged up when I got her. Fixed that, and she rings beautifully!
Problem, I broke the string holding the tension spring. :(. So now I gotta replace that, too.
How do I know when I have enuf tension on the spring? what governs that?
The limited info I have, tells me the spring is to hold the clapper against one of the coil stops. Effectively keeping the clapper from sounding when the AC Ring signal is transitioning from "0 to max positive". But allowing it to sound while transitioning from "0 to max neg".
Or vice versa. Is this accurate?
And would that not result in a Ding, pause, Ding kind of sound?
« Last Edit: August 15, 2019, 08:47:26 AM by Sargeguy »

Offline Key2871

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Weren't those using a light spring and some thing like thread?
I had one once and that's what it had, some have had a light wire that clamps in the there was a screw that brought tension to adjust the bias.
But that's a great question, and should be an interesting thread.
KEN

Online Ktownphoneco

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RB   ....   Here's a link to a file in the Telephone Collectors Library explaining the adjustment process on the type 8 and 78 ringers, and perhaps others.    Ring voltage by the way, is pulsed DC.    If it were Pure AC, you wouldn't require a condenser /capacitor in the ringer circuit.

Link:  https://www.telephonecollectors.info/index.php/browse/bsps-bell-system/by-letter-code/all-letter-codes/c-series-station-installation-and-maintenance/c30-c31-general-apparatus-subsets-components/3282-c31-205-i3-numbered-type-ringers-tl/file

Jeff Lamb
« Last Edit: August 11, 2019, 04:38:36 PM by Ktownphoneco »

Offline RB

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Thanks Jeff.
I find myself having to switch between LB and CB, because I cannot it seems stay on just one road.
I need to include the forks, spoons, and knives found along the way.
So, I conclude, that a Ringer used purely in a LB environment, needs no Condenser, OR a bias spring...as the magneto will supply equal amounts of positive going signals, and negative going signals = Ding, a-Ling, a-ling...

Is this accurate?
The pulsed DC was my next rout.
Now I can see how the mfgr's were able to double the amount of stations on a given line.
albeit, now, we have another sandbox to play in.
DC + on left coil to ground, = Pulsed Ding,Ding??
DC + on Right coil, with bias spring, = nada
So, only ringers with a bias spring on the right coil, will respond to +DC on the Left coil, to ground.
Is that accurate?
Now, we must configure each station to be a "A or B" responder.
So...Now, we get into the relm of How much tension needs to be on an "A" ringer, or a "B" ringer???
That does not sound right.
What is it that requires an adjustable spring on a bias ringer?
Are we talkin line length here??

Offline Jack Ryan

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The short answer to how much pressure is required is - enough to stop bell tinkle.

Bell tinkle is the various dings that are generated when:
  • a handset is listed/replaced
    a parallel phone is operated
    a dial is operated on a parallel phone
    the weather causes overhead lines to touch
    the next door neighbour attaches his butt set to your line to make a free call
    other things I have forgotten

Bell tinkle generally doesn't happen on magneto lines and bells in magneto telephones don't have bias springs. It became a problem with the introduction of common battery (CB) because there was then a DC voltage on the line which, depending on its polarity, could pull the bell armature one way (ding) or the other (dong).

Nothing to do with ring generator ramp-up.

Auto systems have the ring signal superimposed on a DC voltage so that the exchange can detect that the subscriber has picked up. The DC current from the exchange that is drawn when the receiver is lifted is used to cancel the ringing signal - this is called ring trip.

There is no need for a bell capacitor on magneto circuits but on CB systems, if it were not for the bell capacitor, the phone would constantly seize the line (depending on the telephone circuit design). On auto systems and on CB manual systems that use ring trip, a bell capacitor is required as Jeff mentioned to prevent a DC current from flowing through the bell and rendering it inoperable.

There are exceptions because there are hybrids that are part CB and part magneto but these are less common.

The subject of bell bias is interesting because of the different approaches taken in different jurisdictions. In the US, bias springs were used from the first CB telephones until electronic ringers were introduced. In the UK, bias springs were dropped in (from memory), 1924.

OK, some of us are easily amused.

Jack

Offline Jack Ryan

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Thanks Jeff.
I find myself having to switch between LB and CB, because I cannot it seems stay on just one road.
I need to include the forks, spoons, and knives found along the way.
So, I conclude, that a Ringer used purely in a LB environment, needs no Condenser, OR a bias spring...as the magneto will supply equal amounts of positive going signals, and negative going signals = Ding, a-Ling, a-ling...
Is this accurate?

Not really. I think I addressed that in my last post.

Quote
The pulsed DC was my next rout.
Now I can see how the mfgr's were able to double the amount of stations on a given line.
albeit, now, we have another sandbox to play in.
DC + on left coil to ground, = Pulsed Ding,Ding??
DC + on Right coil, with bias spring, = nada
So, only ringers with a bias spring on the right coil, will respond to +DC on the Left coil, to ground.
Is that accurate?

No, that is another subject altogether. Superimposed ringing for selective party line ringing did use a DC offset plus a valve (tube) to ring a particular phone but this is different from the DC plus ringing signal used on a normal auto line. A bias spring is always in the same place - it is not used to determine which party rings.

Quote
Now, we must configure each station to be a "A or B" responder.
So...Now, we get into the relm of How much tension needs to be on an "A" ringer, or a "B" ringer???
That does not sound right.

No it isn't because the bias is to stop tinkle, not to implement selective ringing. I think leave selective ringing and party lines out of the discussion as it just complicates the issue.

Quote
What is it that requires an adjustable spring on a bias ringer?
Are we talkin line length here??

The adjustment is to cope with various amounts of tinkle and for springs that get tired over time. A telephone on a long line will generally tinkle less because the combination of line resistance + bell DC resistance + the bell capacitor makes an RC filter. This filter smooths out the pulses (momentary shorts and open circuits) that would cause bell tinkle. The extra line resistance might also reduce the ring intensity (power) requiring a softer bias spring.

E&OE

Jack

Offline dsk

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The way to solve bell tinkle is different from country to country, I do not believe the German phones did hav any ant tinkle device, and used here in Norway they always made those sounds. We use 90V for ringing, Germany use 60V.

Most Norwegian phones had a spring from 1934 to 1967. (pictures) Usually the tension was OK from the maker, but on long lines (or to may phones on the line  8)  ) you had to weaken the tension to get loud ringing. All this was done in the field, by hand with no instruments.

The 1967 modell had electronic ringer, and that one made sounds when another rotary was used! 
As a (naughty) kid I bilt my selves a test phone (with press to talk), and tested it out on the basement telephone wire junction box and hooked my clips on one pair, and called one neighbor. He answered, and so did the other where I called from, I kept silence and both claimed the other to have called...  From 82 and the start of push button phones here the problem was forgotten  ;)

The outdoor ringers did never have any anti-tinkle device, so you could always hear tha[size=78%]t they were dialing.

The UK phones had often a thermistor in series with the ringer to prevent tinkle, later they made a system with master and slave jacks with a 3'rd wire for the ringers.[/size]


[size=78%]dsk
[/size]


 
« Last Edit: August 12, 2019, 04:02:19 AM by dsk »

Offline Jack Ryan

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The thermistor in the UK was used in two party shared service where if one party dialled, the other party's phone tinkled.

The GPO dropped the bias spring in 1924 when the No 10 dial was introduced. The modified circuit used with the No 10 dial prevented (own) tinkle while dialling electrically. There were very few phones in parallel as people only had one phone (austerity) if at all.

Much later, when additional phones were used, the plug & socket system was introduced to mitigate bell tinkle.

Jack

Offline Sargeguy

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Most western electric ringers were equipped with a bias/tension screw and a hook for a spring even if the spring was not installed.  Some of the earlier ringers were LB specific and do not have it. 
Greg Sargeant
Providence, RI
TCI /ATCA #4409

Offline RB

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Thanks guys!
I rang it from a small magneto without the bias spring attatched as I still have not replaced the string. but will.
It rang beautifully!
I am wondering, tho... what will it sound like after the bias spring is re installed? and rang from a magneto?
I may have to leave it out???

Offline Jack Ryan

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I am wondering, tho... what will it sound like after the bias spring is re installed? and rang from a magneto?
I may have to leave it out???

If the spring tension is low, the bell will ring without any problem. If the spring stops the bell from ringing or makes it quiet, it is too tight.

Jack

Offline RB

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Ok, cool.
I will install spring with as little tension as possible, and still look normal.
It is adjustable anyway.