The ding effect

[Telephone Guy]

Hello,

I've two questions, one of which ( for the majority of users on this forum ) will I'm sure be a piece of cake, the other maybe not. I'll post the second question separately, but for now: we have four telephones, all of which I'm fairly sure are the old-style 782 type ( DMTF dialling including # and * keys ). When you pick up the receiver on one of these, any given one or combination of the others will 'ding' randomly; sometimes they do it, sometimes not. On a couple of the phones, the actual bell in the telephone you're picking up will do it when you lift the receiver.

I'm pretty sure this is a relatively simple fix; in fact, I've got a feeling I've probably done it myself in the past ... something along the lines of inserting a resistor or capacitor across two of the terminals where the line comes into the phone ...? Not quite sure, but that's where you come in! If anyone can enlighten / remind me, it will be appreciated!

By the by, as per an earlier post, incoming volume is very much an issue on these phones due to our distance from the exchange, so could you let me know whether any suggested fix might have any possible detrimental effect on that? ( I'm guessing not, inasmuch as presumably the 'ringing' current comes in on different terminals than the 'speech' current ... but as you gather, I'm far from expert in these things!! )

As always, any input gratefully received.

[Telephone Guy]

Following on from my earlier post … so: we’ve got four telephones which I’m reasonably sure are all BT 782’s ( DTMF dialling with # and * keys, various ages ). Depending on the answer to my previous query about the ‘ding effect’ ( or to be more accurate, depending on whether the answer to that has any bearing on the answer to this ) ...

I’ll admit up-front that this is another one like the previous telephone-amplifier question, to which I suspect the answer is basically just ‘no’. However, on the off-chance:

Is there any way to configure the phones in question in such a way that when one phone is in use, the others are effectively disabled until the receiver is replaced on the phone being used? The phones are in quite separate areas of the house, and it’s frustrating to be constantly coming in in the middle of other people’s conversations!

[Dave Moll]

The "ding" is caused by the change of voltage across the line when a telephone goes "off hook". Given that the bell is energised by the changing voltage of the AC ringing current, this smaller change in voltage may be enough to cause the armature to move once.

[Pellseinydd]

Originally Posted by Telephone Guy

Following on from my earlier post … so: we’ve got four telephones which I’m reasonably sure are all BT 782’s ( DTMF dialling with # and * keys, various ages ). Depending on the answer to my previous query about the ‘ding effect’ ( or to be more accurate, depending on whether the answer to that has any bearing on the answer to this ) ...

<snip>
Is there any way to configure the phones in question in such a way that when one phone is in use, the others are effectively disabled until the receiver is replaced on the phone being used? The phones are in quite separate areas of the house, and it’s frustrating to be constantly coming in in the middle of other people’s conversations!

Now you know what the old 'shared service' party lines were like!

There used to be a small device known as a 'privacy' adapter which you plug into a socket - then you plugged two phones into the adapter. If one phone was in use, the other phone couldn't be used/ overhear. Can't remember if it worked with more than one pair of phones. ]

To get around the problem, why not fit a small one exchange line, up to 8 extensions PABX (you need to wire four up) and it will solve the problem plus the ability to transfer calls or call between phones. PABXs come up on eBay quite cheaply - I picked up a Panasonic 3 line 8 extension system for 99p plus 6.99 carriage. Keep our eyes open.

Ian J

[Graham G3ZVT]

Originally Posted by Telephone Guy

Is there any way to configure the phones in question in such a way that when one phone is in use, the others are effectively disabled until the receiver is replaced on the phone being used? The phones are in quite separate areas of the house, and it’s frustrating to be constantly coming in in the middle of other people’s conversations!

Originally Posted by Pellseinydd

Now you know what the old 'shared service' party lines were like!

<snip>

To get around the problem, why not fit a small one exchange line, up to 8 extensions PABX (you need to wire four up) and it will solve the problem plus the ability to transfer calls or call between phones. PABXs come up on eBay quite cheaply - I picked up a Panasonic 3 line 8 extension system for 99p plus 6.99 carriage. Keep our eyes open.

Ian J

I tried that at home firstly 20 years ago with an Omnicom FS2828 which I wired into all rooms, and latterly with my current Asterisk system. I have come to the conclusion that there is something to be said about the simplicity of parallel phones in a domestic situation.

I have a compromise arrangement now, the wired POTS phones in the lounge, hall, kitchen, and bedroom are in parallel on ext 301
There is a DECT handset on 302 and my "private" POTS phone on 303.
Two Android phones run CSipSimple on 303 & 304 and work inside or outside the LAN.

[Graham G3ZVT]

The technical term is not "ding" I mean that's just silly.
It's "tinkle"

[nutteronthebus]

The first question is how are they wired 1: as a plan 1A ( old style hard wired )
2: new plan with sockets

the 1st needs 4 wires this includes a anti tinkle wire that shorts out the bell . The second requires 3 wires but the REN of the phone needs to be increased by fitting a 3K3 resistor in series with the bell and a master socket

Dave

[Dave Moll]

Let's unpick that a bit.

Surely, the "old plan" had bells in series and thus didn't need an "anti-tinkle" wire. One end of the internal ringer was connected to the green wire so that either an external ringer or a shorting link (if no further ringers) could be connected between it and the white wire. A fourth wire was only needed when an earth connection was required (e.g. for shared service or for recall on a PBX).

With new plan the bells are connected in parallel via the blue ("anti-tinkle") wire to an external capacitor in the master socket. The purpose of a series 3.3K resistor bodge is effectively to reduce the REN of an individual telephone* so that up to four can be connected in parallel without exceeding the maximum permitted REN of 4.

*I refer to this as a bodge, as the official modification was to replace the 1K ringer with a 4K one.

[nutteronthebus]

The N diagram N4502 shows 4 wires A & B for the line G for bell and Bn for bell tinkle

Dave

[ColinTheAmpMan1]

Originally Posted by rambo1152

The technical term is not "ding" I mean that's just silly.
It's "tinkle"

I know absolutely nothing about phones, but isn't "tinkle" equally as silly as "ding"? Tinkle is also "toilet number ones", isn't it? The problems with technical jargon...
Colin.

[Telephone Guy]

I'll look at the 'ding effect' posts for now, as I think the other problem is going to be a whole other ball game.

For the record, I'm sticking with 'ding' rather than 'tinkle' because 'ding' implies a single strike of the bell, whereas 'tinkle' implies more than one. That's my story and I'm sticking to it.

Also for the record, I'm old enough to remember party lines first-hand; not that we ever had one, as far as I can recall, but I was around when they were. To give you some idea, our first phone had an exchange name followed by a three-digit number. Those were the days ...

I digress. Surprisingly, for someone who acquired the bulk of their electronic knowledge from a Philips Electronic Engineer at the age of around nine or ten ( give or take ), I do actually get some of this, even down to the circuit diagrams obligingly provided - the operative word being 'some'. I do, for example, understand Dave's explanation of why the 'ding' ( still going with 'ding' ) happens in the first place.

To answer nutteronthebus ( I feel weirdly disrespectful using that name for someone clearly more knowledgable on the subject than I am ...! ), this is where it all starts to get a bit blurry for me. I don't know the plan numbers you mention, but the phones are all plug-and-socket., so plan 2, I guess. From the words 'the first needs 4 wires ...' to pretty much the bottom of the page, the rest is a mixture of bits I do understand and bits I don't. I can more or less read a circuit diagram, which is to say I know a capacitor from a diode - I even know more or less what a capacitor and a diode do - but the exact function of each component within the complete circuit is above my pay grade, which implies that I ever had a pay grade relating to this type of work, which I didn't. To give you an example, I know that a 3.3k resistor will reduce the REN ... I'm just not entirely sure why.

If - and I do say 'if' - I've gathered correctly, the solution to this problem is going to depend on how the incoming line is 'strapped' ( correct term? - apologies if not ) in the first place; which in turn means I'd have to open up each of the phones, take a photo of the connections at the back, and post the photos on here ( it being the case that all four phones were bought separately and may very well not be strapped identically ).

Or am I over-thinking this and there's a far simpler solution?

[dagskarlsen]

Originally Posted by Telephone Guy

Hello,

I've two questions, ....
I'm pretty sure this is a relatively simple fix; ...

As always, any input gratefully received.

As usual you will get lots of different answers, I am happy with this solution, and it solves bothe problems, tinkle and privacy:

https://www.epanorama.net/circuits/tele_privacy.html

You may use a quadrac instead, then you just follow the same chemeatics, but the diac is not needed and may just be a wire.

You need one quadrac in each telephone, but it is so small that you will always get the room you need for it.

For those who use modems or ADSL, this may even reduce the phones reduction of the data speed.

dsk

[Dave Moll]

Originally Posted by Telephone Guy

I know that a 3.3k resistor will reduce the REN ... I'm just not entirely sure why.

If you think of REN as a measure of the current drawn by the ringer, then increasing the resistance will reduce the current drawn (according to Ohm's Law).

Originally Posted by Telephone Guy

I'd have to open up each of the phones, take a photo of the connections at the back, and post the photos on here ( it being the case that all four phones were bought separately and may very well not be strapped identically ).

Doing so would certainly be helpful. 700 series telephones are not difficult to open up.

[dagskarlsen]

Originally Posted by Dave Moll

If you think of REN as a measure of the current drawn by the ringer, then increasing the resistance will reduce the current drawn (according to Ohm's Law).

Doing so would certainly be helpful. 700 series telephones are not difficult to open up.

We have another thread with the REN load discussed here: https://www.vintage-radio.net/forum/...ad.php?t=42123

The only thing I am missing in that hence is the need of approximately equal equal power draw on equal phones. By my opinion the use of a series capacitor will result in less loss of power, but it will also be difficult to calculate. North American phones uses about 1/2 microFarad so adding an extra 1 uF in series with each ringer could be a start.

dsk

[nutteronthebus]

Hi this site may help https://www.britishtelephones.com/pstconv1.htm

Dave

[bluepilot]

Originally Posted by ColinTheAmpMan1

isn't "tinkle" equally as silly as "ding"? Tinkle is also "toilet number ones", isn't it? The problems with technical jargon...

To give someone a tinkle was quite a common expression at one time. There was even a song "Will Willy tinkle Tilly on the telephone tonight". I suppose language evolves.

[Herald1360]

"Ding" on pickup is just a subset of "Tinkle" which is a reasonable description of the sound you would get from parallel wired 'phones' bells when dialling out using a real loop disconnect dial. Tinkle as a word I suspect originated in the bell arena and has subsequently been applied to other, similar sounding, activities. A suitable amount of thought was exercised in the early days of dialled telephones in order to get rid of this and other undesirable problems. Nowadays the sound of the DTMF tones as you push buttons is a lot easier on the ear than the explosive pulses you would have got from a phone with no or malfunctioning dial "off normal" contacts shorting out the receiver.

[G4YVM David]

We always used "tinkle" at home...I'll give you a tinkle later..

Tinkle is much more poetic than ding.

[russell_w_b]

Originally Posted by nutteronthebus

The N diagram N4502 shows 4 wires A & B for the line G for bell and Bn for bell tinkle

Dave

That would be because the only bell capacitor is in the first (RH as shown) telephone. This capacitor also serves as part of the C-R spark-quench circuit which causes 'tinkle' if unsuppressed. The other telephones have their capacitors disconnected so need a route back to quench their dial pulses when a call is made from them.

I've always referred to the sound as a 'ting' (single) or a 'tinkle' (multiple). A 'ding' is what you get in a car when you bash it. A 'ting' used to happen of a night about midnight, during automatic line testing, where I believe the line polarity was momentarily reversed. I used to kid my mam on that the line was being tapped!

[OscarFoxtrot]

Originally Posted by Telephone Guy

Is there any way to configure the phones in question in such a way that when one phone is in use, the others are effectively disabled until the receiver is replaced on the phone being used?

In theory it would be possible to give phones series priority, by wiring one wire of each phone through the hookswitch of the previous one.

This might require a Tele 740 or at least an extra hookswitch, and I don't think it was a standard Plan.

The first phone on the line would have secrecy against all phones lower down the chain, but would interrupt an existing call.

The "privacy adapter" mentioned by dagskarlsen, or a smilar circuit, is probably easier.