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ringer bias spring idea

Started by NorthernElectric, March 21, 2015, 07:59:57 PM

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If you read my post here, you know I am planning on franken-building a wood subset box using a modern network and touch tone keypad concealed inside.  The ringer was a bit of a dilemna.  I am keeping my eye out for a parts box with a B1N ringer, and in the mean time have obtained an older (49B?) 2500 ohm ringer.

Neither the B1N, nor the ringer I have, are equipped with a bias spring.  This leads to bell tinkling during dialing of any phone on the line.  I might be able to use the spring from a B1A on the B1N.  Photos I have seen have the adjustment notches at the top so I'm hoping the bottom has the hole that the other end of the spring sits in.  But that idea will have to wait until I actually get one.

The older ringer I have has no place to attach a spring, so I have been trying to think up different types of springs I might use, and ways to attach them.  I came up with this idea.  I have a small 'netbook' computer on which I had replaced the keyboard.  I still had the old one in a junkbox so set about finding it and then prying off a few keys to see what was under them.  Turns out it had a small silicone rubber covered spring in each key, so I cut one out and tried it on for size.  This keyboard had a very short key travel, a feature common on laptops, netbooks, etc., and all of the springs were affixed to a thin plastic sheet with the contacts printed on it.  I cut out a piece with one of the springs on it and tried it on for size.  It was a snug fit and had to be compressed slightly to fit which is exactly what I'd hoped for.  I tried it out and it seems to do the trick.



Hmmm...very interesting. Nice work!
Doesn't the ringer have a bias spring or maybe a missing bias spring? It seems a lot of them are missing, a member of ATCA had some reproductions made not long ago that work perfectly. I have some somewhere but am not able to put my hands on them right now.
Harry Smith
ATCA 4434

"There is no try,
there is only
do or do not"


Quote from: HarrySmith on March 21, 2015, 09:25:38 PMDoesn't the ringer have a bias spring or maybe a missing bias spring?

I didn't see anywhere to put one and it doesn't look like it ever had one.  I thought that equipment used on lines that didn't have automatic dialing service at the central office didn't need a biased ringer so they didn't put springs on them.  But, I'm new at this so I don't know for sure.


I think any phone that was made with the possibility of dial service had ringers with bias springs.  For instance any 302, manual or dial, and any 684a subset.

The keyboard spring seems to be a very ingenious idea.  If it is not too thick to interfere with regular ringing, it seems perfect. 

However, your average key on any computer keyboard is probably only capable of taking so many key strokes before failing.  At 20 "key strokes" per second attached to the ringer, that will add up to a lot of spring motions over time.  I hope it lasts for a while.

-Bill G