Fun project with the kids - need guidance

[dsk]

No,I have never even seen a KTAS exchange.
If you may get a few indicator, it would be fine, if not a LED and a resistor may do the job, but it will only flicker while the caller use the generator.

I guess that the simplest circuit to use is the German field exchange from WWii.
You may even simplify that, and use std stereo jacks and plugs, A regular 2 pole switch on each line.

[poplar1]

Excuse my ignorance (total newbie to antique phones), but basically what you are saying for #1 is that the what's circled in red on the image below (I guess relays?) is compatible with magneto phones, but the blue part is for dial phones? ...

The drops circled in red are the style you would need in an all-magneto switchboard. I don't think there is anyway to connect any of the 5 trunks to another trunk (electrically, they are wired so that only one trunk can be connected to a particular phone). And the lines (phones) are common battery type where picking up the receiver signals the attendant.

[dsk]

For me the many of those designs looks pretty complicated.  The indicators are fine tuned relays with manual reset. The british field exchanges used neon glow lamps, a resitor and a LED will do the job. Here incated as a circle with an X inside.
This is the most simple working solution I may find. And why stereo plug? Yes it is smart with tip and ring. It will also be Compatible with the field exchang  SB-22/PT :-)

[dsk]

If you use one of those with plastic like this you may trim the plastic so the metal part becomes 2 mm longer, and fits in the German war field exchange.

[poplar1]

Examples:

https://www.ebay.com/itm/134338368766

https://www.ebay.com/itm/325463234162

https://www.ebay.com/itm/374616447196

[Stormcrash]

A switchboard might be a bit overkill and complicated.

Something simpler you could do is to hook all the phones together on a single party line and assign each station a ring pattern. Farmers used to do this out between their farms to talk to each other

Something like
1 ring - first phone
2 short - second phone
1 long 2 short - third phone

Added benefit that you could pick up on more than one phone and have a big "conference call" too

All you would need to do for this is to put some batteries in the phones and run two wires from one phone to the next in a chain

[Ohliuw]

I ended up buying the KTAS switchboard. I will only have it in the fall and will report here after.

Meanwhile, I started cleaning up the 2 phones we got far, starting with the jydsk.

First issue : when I opened the microphone, I found this "dust" inside - would the mike still work or needs something to replaced?



Second issue : I need to remove the crank to be able to open the box and clean the mechanism. It seems to be stuck. Where do I "push" to get it out - outside joint (red arrow on the photos) or inside joint (green arrow on the photos?
   


Thanks

[TelePlay]

Meanwhile, I started cleaning up the 2 phones we got far, starting with the jydsk.

First issue : when I opened the microphone, I found this "dust" inside - would the mike still work or needs something to replaced?

If by microphone you mean transmitter, there is a very good chance that what you see is not dust but, in fact, the carbon granules that make the transmitter work - convert sound waves to electrical current sent down the line to the other phone's receiver (where it is converted back to sound waves).

Last time I saw those come up on eBay they sold for something like $100 for half ounce, impossible to buy new and rarely available in bulk.

The carbon granules belong inside the capsule which is directly connected to the transmitter diaphragm and has a wire lead on the front and back of the carbon capsule.

I hope you saved the "dust" and can figure out what went wrong (to allow the granules to escape the capsule) and successfully fix the issue.

Might end up buying a replacement transmitter.

[TelePlay]

Found the topic, $110 asking price

http://www.classicrotaryphones.com/forum/index.php?topic=17989.msg185625#msg185625

If you search the forum for "carbon granules" you will find a wealth of information about them.

[Ohliuw]

If by microphone you mean transmitter, there is a very good chance that what you see is not dust but, in fact, the carbon granules that make the transmitter work - convert sound waves to electrical current sent down the line to the other phone's receiver (where it is converted back to sound waves).

Last time I saw those come up on eBay they sold for something like $100 for half ounce, impossible to buy new and rarely available in bulk.

The carbon granules belong inside the capsule which is directly connected to the transmitter diaphragm and has a wire lead on the front and back of the carbon capsule.

I hope you saved the "dust" and can figure out what went wrong (to allow the granules to escape the capsule) and successfully fix the issue.

Might end up buying a replacement transmitter.

Thanks, I manage to save 90% of the dust. Not sure I will be able to figure out what went wrong as I have no clue how it's supposed to be, so I will most likely shop for replacement transmitter.

I wish I knew this 3/4 days ago as there was a cheap beaten up ktas phone locally, but it seems to be gone now.

How about removing the crank handle? I can't figure it out on the Northen Electric too I Don't want to break something while trying to pull it out.

[TelePlay]

Crank handles are threaded and screwed on with right hand threads so the thread tightens as the magneto is cranked clockwise.

Removal is done by turning it counterclockwise once the tight threads are broken loose. After years of use and the sitting, breaking them loose is the hard part.

The crank and threaded shaft it screws onto are metals that do not rust together (brass, maybe bronze) so it's just a matter of breaking the tight bond, not breaking a rust bond.

Applied heat may help if it's really stick. Others may have good tips on how to remove the crank handle.

[SUnset2]

I'd use a little penetrating oil first, let it soak in, and then turn it sharply counter-clockwise.

[countryman]

Looks like the carbon diaphragm used by this transmitter is broken, too.
Diaphragm and granules were consumable parts and sold individually "back in the days". You will not find them any more. You might find an old replacement handset, but chances are that it has the same issues.

This type of transmitter assembly is quite archaic, sealed transmitter capsules became "state of the art" about 100 years ago. Some manufacturers may have used their older concepts longer.

[HarrySmith]

I have used a screwdriver to hold the gear while loosening the handle. Use one that fits in the gear teeth so as to not damage them then find a spot to brace the screwdriver against or insert between the gears.

[Ohliuw]

Thanks, will try unscrewing them.

Meanwhile, we run into another problem. We tried crossconnecting the two phones- used L1 and L2 on the NE (first and third from the bottom), and as we couldn't find any connection info on the JYDSK, we used the first 2 of the 5 terminals on the top.

It appeared to be working well - when cranking one, it rang on the on the other one.



However, now the JYDSK won't ring at all - whether I crank the JYDSK or the NE - the JYDSK doesn't ring.

We disconnected the terminals, and the JYDSK still doesn't ring (it was difficult to crank, before but was still ringing somehow)

What could be the problem?