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-   -   Using Bellset 41 with a Candlestick 'phone. (https://www.vintage-radio.net/forum/showthread.php?t=71292)

Darren-UK 29th Jun 2011 3:16 pm

Using Bellset 41 with a Candlestick 'phone.
 
3 Attachment(s)
As per title, I've had this ensemble for a good many years but it's been stored away, forgotten, until now.

It works but there's a horrendous click in the receiver when dialling out, this being the reason I stopped using it and stored it away.

Britishtelephones makes it perfectly clear this bellset can/should only be used as an extension bell.

As can be seen in the images, the capacitor and rectifiers have been disconnected and the relay is missing.

I don't have any other bellsets so my question is can I do anything with this No.41 to eliminate the click in the receiver? and, if so, would using it cause any problems with the telephone network(BT)? I have used it like this years ago with no apparent problems though.

Of the attachments, the Zip just contains a gargantuan version of the bellset thumbnail.

TIA.

Dave Moll 29th Jun 2011 6:17 pm

Re: Using Bellset 41 with a Candlestick 'phone.
 
What you have now (following the previous "surgery") appears to be simply a (presumably 1K) bell, so it should behave the same as any other 1K bell.

I also have a bellset 41 - which I have wired up simply as an extension bell connected (via the usual 3.3K resistor) to the externally capacitated bell wire.

Incidentally, given that a bell should not be doing anything while the loop is made (i.e. off-hook), at what point does the click occur?

Darren-UK 29th Jun 2011 7:45 pm

Re: Using Bellset 41 with a Candlestick 'phone.
 
There's a very loud click in the receiver at commencement of dialling and again when the dial hits the stop following the dialling of each numeral.

Dave Moll 29th Jun 2011 9:32 pm

Re: Using Bellset 41 with a Candlestick 'phone.
 
Just to clarify - this only occurs with this bell(set) connected?

Quote:

Originally Posted by Darren-UK (Post 444944)
I don't have any other bellsets...

In that case, what are you using to provide the induction coil for the candlestick - and how is the setup wired?

Darren-UK 30th Jun 2011 4:20 pm

Re: Using Bellset 41 with a Candlestick 'phone.
 
There is no induction coil and the instrument's worked seemingly quite alright without it. The nuisance is that almighty click in the receiver, which I don't think is down to there being no induction coil?

The terminals in the No.41 are difficult to cross-refer to those of Bellset 1A, which is relevant as that latter is what the 41's trying to operate as. I'm not even sure where to connect a 3.3K resistor although, again, it's seemingly been fine without one.

The linecord is a non standard one. With BT colours in brackets it's connected Black (white) to T4, Red (Green) to T9 and Yellow (Red) to T7.

The telephone cord is connected to T4, T7 and T9 but it's difficult to tell which wire is which.

The bellset apparently began life as a No.1. On the rear it has the crossed out markings 'GPO (something illegible) No.1'. Below that is '41 FHR 54/1' so presumably the conversion was done in 1954.

Dave Moll 30th Jun 2011 5:23 pm

Re: Using Bellset 41 with a Candlestick 'phone.
 
What model of candlestick 'phone is it?

I was (presumably falsely) assuming a model 150, but that doesn't have terminals numbered as per your above post.

By the way, given that your 41 is just a bell (with, presumably, only two terminals in use), I would have thought this would need to go between the black and green wires of your B/R/G/Y line cord - with the 3.3K resistor in series with the bell if necessary. Where is it currently connected?

Darren-UK 30th Jun 2011 5:47 pm

Re: Using Bellset 41 with a Candlestick 'phone.
 
The telephone is a 150 (marked as being made by Plessey, 1930) although a GEC dial has been fitted.

The terminals are those on the No.41, just a strip marked 1 - 9.

dagskarlsen 30th Jun 2011 6:38 pm

Re: Using Bellset 41 with a Candlestick 'phone.
 
Try to move red from candlestick; from terminal 9 to terminal 3. (or just tape/isolate it)
dsk

Dave Moll 30th Jun 2011 8:04 pm

Re: Using Bellset 41 with a Candlestick 'phone.
 
Quote:

Originally Posted by Darren-UK (Post 445340)
Theterminals are those on the No.41, just a strip marked 1 - 9.

I thought you were referring to the 150. Given that you are using it without an induction coil, I am interested to know how you have it wired to the telephone line.

Darren-UK 30th Jun 2011 9:19 pm

Re: Using Bellset 41 with a Candlestick 'phone.
 
Quote:

Originally Posted by dagskarlsen (Post 445360)
Try to move red from candlestick; from terminal 9 to terminal 3. (or just tape/isolate it)
dsk

That caused bell tinkle whilst dialling :-/

I've just called someone on it and he said I was coming through loud and clear, so I'm going to leave it as it is and put up with the click until I can obtain a proper No.1 or No.25 bellset. The whole thing is a bodge too far and beyond my abilities.

Many thanks anyway.

dagskarlsen 30th Jun 2011 10:18 pm

Re: Using Bellset 41 with a Candlestick 'phone.
 
It is numerous ways to make a well working subset. You have a capacitor there all ready. About any induction coil, or even a coil with only one winding may improve the set.
On the other hand, and whatever said about the risk of demagnetize the receiver, this will take many hours of continuously telephone conversations, and should not be a great risk.

If the phone rings, you may ring out, and the other end doesn't say anything about it, it works well enough.

Fetling this is ideal for bad winter weather days.

dsk

Darren-UK 1st Jul 2011 1:08 am

Re: Using Bellset 41 with a Candlestick 'phone.
 
I've boxed it up and put it away again now, until such a time as a proper bellset turns up. The telephone itself needs some cosmetic work anyway, plus the flex from bell to telephone is now in tatty condition although not yet giving any problems in use.

Herald1360 1st Jul 2011 12:26 pm

Re: Using Bellset 41 with a Candlestick 'phone.
 
If there's no induction coil, presumably there's line current through the receiver when the phone is off hook. Won't the dial anti tinkle contacts remove this current at commencement of dialling and switch it back as the dial reaches its stop, thus causing the loud clicks experienced?

Maybe a couple of inverse parallel diodes (perhaps in series with a capacitor) across the receiver might reduce the ear'ole bashing effects by limiting the signal volatge. You could try silicon, schottky or germanium depending on desired clipping level.

I'm not a telephone expert, so this may be nonsense......

dagskarlsen 1st Jul 2011 7:59 pm

Re: Using Bellset 41 with a Candlestick 'phone.
 
I have to guess a little, but since it obviously works, I'm quite sure:
Line (A-wire) coming in on Yellow, connected to ringer, and Receiver.
The other end of the receiver is connected to the hook switch.
Line (B-wire) is the black, this goes thru the dial and the transmitter to the hook switch. When you go offhook this forms a primitive but working telephone circuit.

The Red wire has to be the ring-signal wire, and should not have been connected to the candlestick, when going off hook the receiver will be connected in parallel with all the ringers in the house. When dialling the receiver and the ringers will be shorted by one contact set in the dial, another set shorts the transmitter. To reduce the click in the receiver this set should close first, and open last. Due to the capacitor in the master socket, the opening of this contact will generate a click in the receiver.

By disconnecting the red wire from the candlestick this should be much better.
Putting in an induction coil, and capacitor makes the telephone much better.

The simplest sidetone circuit here will be a capacitor in series with the receiver, (The one in the ringer box in series with the green wire to the candle stick. A coil with high AC resistance and relatively small DC resistance across the receiver and capacitor. (This coil could be e.g. a relay.)

More complex with an induction coil (transformer), the only limitation is the need of sending the full current thru the dial and thereby the transmitter.

I will try to make a diagram or two.

dsk

dagskarlsen 1st Jul 2011 9:20 pm

Re: Using Bellset 41 with a Candlestick 'phone.
 
1 Attachment(s)
dsk

dagskarlsen 1st Jul 2011 9:53 pm

Re: Using Bellset 41 with a Candlestick 'phone.
 
1 Attachment(s)
Simple sidetone circiut.
dsk

dagskarlsen 2nd Jul 2011 9:09 am

Re: Using Bellset 41 with a Candlestick 'phone.
 
1 Attachment(s)
Antisidetone version:
Coil and capacitor from this: http://www.britishtelephones.com/stc2724.htm

All 3 diagrams has not compensated for lo ohms ringer, if needed a (capacitor or) resistor could be added in series with the ringer.

dsk


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