Old telephone ringer stompbox

[SeneX225]

The idea: I want to turn an old phone ringer into a stompbox that rings while I hold the button.

Backstory: Recently I've acquired a number of old non-working line phones. I realized that repairing them is of little relevance, so I've decided to strip them into parts I can use elsewhere. Besides the obvious receiver there are two other parts that interested me: the keypad and the ringer. The former I want to try to turn into usb/midi controller, but I'm still doing my research to check if it's even possible. The latter seemed way simpler, at least on the surface.



There are two wires coming out of cylinder coil. After a simple continuity check I determined their polarity (which wasn't specified on the board and they were just designated W1 and W2). I've hooked them up to a power jack and plugged a 9V 500mA DC power supply in, and it rang... only once, though. It struck a top bell when activated and stayed there, only retracting back to original position once unplugged.   



Okay, thought I, maybe it needs AC after all, so I plugged in a 9V 1A AC. The result was nothing.

Which is where I'm currently stuck. So, my question is:

How to make it work, if it's even possible? Maybe it needs some kind of impulse generator?

Thanks!

[GibsonGM]

It's a great idea - I've done this with old doorbells that work on 18V, and had success. But I believe old phones used something like 90VAC, and may have had filtering to restrict the frequencies they respond to, to prevent accidental rings.

I think your sensing 'impulse generator' was the right idea.  I looked around for a minute, and some ppl seem to have made these work by using a 555 timer to boost input voltage (perhaps 18V; 2 9V batteries) to 90 or so, at about 20Hz.  I KNOW some of the 'old timers' around these parts used to work with such objects as phones, and you are sure to get a much more clear answer once they see this post   

* Caveat:  The fact it 'moved' on 9V may mean I'm totally wrong about the high voltage - that's only what I've read! Can you post the coil's resistance?

[SeneX225]

* Caveat:  The fact it 'moved' on 9V may mean I'm totally wrong about the high voltage - that's only what I've read! Can you post the coil's resistance?

As far as my research goes the bell will work with whatever voltage it gets but higher the number the faster it will move, thus getting louder. 

The coil resistance reads 1,7kOhms.

[GibsonGM]

OK...well, if it 'rang and stuck' on 9V, I see no harm whatsoever in hitting it with an intermittent signal (ie, a pulse). You can try a 555 at low frequency and see if its output is enough to trip it, tho the 555 puts out around 2/3 VCC, IIRC, which may not be enough.   So you may need to amplify that output to get a higher voltage - or run the 555 on something higher than 9V tho <15V (max rating of 555, with 18V MAX rating (death)).
Play around!    I've found a few ways people have done this, some more complex than others....

[SeneX225]

OK...well, if it 'rang and stuck' on 9V, I see no harm whatsoever in hitting it with an intermittent signal (ie, a pulse). You can try a 555 at low frequency and see if its output is enough to trip it, tho the 555 puts out around 2/3 VCC, IIRC, which may not be enough.   So you may need to amplify that output to get a higher voltage - or run the 555 on something higher than 9V tho <15V (max rating of 555, with 18V MAX rating (death)).
Play around!    I've found a few ways people have done this, some more complex than others....

The 555 sounds like a fine idea. However, there's a problem: I don't have a clue how to do it, at all. I'm almost a complete newbie in these things (that's why I ask for help so frequently), so bear with me here.

Quick search showed that 555 is a chip, but that's a dark forest for me as of yet.

[GibsonGM]

Ok, the internet will be your friend! 
Is it easy for you to get 'parts' where you are?  (ie, are you in US/Europe and know where/how to buy chips, transistors etc?)

[SeneX225]

Ok, the internet will be your friend! 
Is it easy for you to get 'parts' where you are?  (ie, are you in US/Europe and know where/how to buy chips, transistors etc?)

Yes, I have a couple of local radioshacks where I get all the parts. I just checked and at least one of them has the chip in question (NE555P variant).

[GibsonGM]

You could step up the voltage with a 555 flyback circuit, but that may be a bit above your pay grade.   

If you read this article https://www.epanorama.net/circuits/telephone_ringer.html   The section "50/60Hz ring voltage generated from mains voltage"   seems sensible.  You'd have to pick up the required parts, but if you really like the idea of the loud, ringing 'phone', this is probably the best way....USING PROPER SAFETY of course, KNOWING safety before you mess around

I still would get some 555s and build an oscillator (Billions of articles on internet) and try it out, however, since it's a great hobby IC with SO many uses - you will see it over and over.... 

HTH!

EDIT:  YOU HAVE A RADIO SHACK STILL??  LOL, am I communicating back in time???     They may well have a transformer you can use as in the article (they should, 120:12V)

[SeneX225]

I still would get some 555s and build an oscillator (Billions of articles on internet) and try it out, however, since it's a great hobby IC with SO many uses - you will see it over and over.... 

I sure will!

If you read this article https://www.epanorama.net/circuits/telephone_ringer.html   The section "50/60Hz ring voltage generated from mains voltage"   seems sensible.  You'd have to pick up the required parts, but if you really like the idea of the loud, ringing 'phone', this is probably the best way....USING PROPER SAFETY of course, KNOWING safety before you mess around

The article suggests, as far as I can grasp, building a 12V-120V (Or a 12V-220V in my case since I'm in Europe) transformer. However, as I meantioned earlier I've tried plugging in a 9V AC 1A power supply (also a 12V AC 3.3A I found laying around) and nothing happened.

Okay, thought I, maybe it needs AC after all, so I plugged in a 9V 1A AC. The result was nothing.

Am I getting something wrong?

EDIT:  YOU HAVE A RADIO SHACK STILL??  LOL, am I communicating back in time???     They may well have a transformer you can use as in the article (they should, 120:12V)

They're not the Radioshacks, but I call them that because people instantly understand what I mean.

[GibsonGM]

Try it with the 555 first    There are MANY web pages devoted to this little gem, it is in 1,000s of products and has been around forever. 

But first, experiment:  If you 'pulse' the coil wires by touching one of the leads to it repeatedly (with the other attached), does it 'ring' over and over?  If so, then that tells you it works - as long as it's loud enough for what you want to do and all that.  Observe if it hits just one bell over and over (which would tell us it needs AC)

[SeneX225]

Try it with the 555 first    There are MANY web pages devoted to this little gem, it is in 1,000s of products and has been around forever. 

But first, experiment:  If you 'pulse' the coil wires by touching one of the leads to it repeatedly (with the other attached), does it 'ring' over and over?  If so, then that tells you it works - as long as it's loud enough for what you want to do and all that.  Observe if it hits just one bell over and over (which would tell us it needs AC)

While testing this an interesting development occurred: I've plugged in an AC 9V 1A power supply mentioned earlier and accidentally touched the plate connected to the hammer, and it rang... and did not stop! Not until I touched another side of said plate, which stopped the hammer.



I am both relieved and confused.

[MikeA]

Ringers are tightly tuned to a specific AC frequency, evolving from party lines where there were multiple instruments on one wire pair.  Different frequencies rang different houses.  I don't know the frequency scheme in EU, you should be able to Google it, but something like 20, 30, 40, 50 or 60 Hz.  Another scheme was 22, 33, 44, 55 or 66 Hz. Somewhere between 48 and 110 volts AC should do it.  After party lines went away, most phones were fixed in the 20-30 Hz range so I'd start there.

[GibsonGM]

Yes, per the article I linked above. I'm really just curious if it can be hacked to make something useable at manageable voltages that one can easily provide within a pedal context   

[SeneX225]

While searching on how to make a 555 oscillator, I found this at the same local radioshack:



It's some Arduino module and has DC 5-15V with 1Hz-200kHz frequency. Will it suffice for this particular project?

[duck_arse]

rocking armature, is that the right thing? I have an idea these run on DC, and when the coil energises one way [when the connections are in the right place] it breaks the connection to that end of the coil, and makes the connection to the other end. this throws the dinger, breaks the connection, makes the connection, etc. also large sparks.

so yes, probably connect to the moving plate part, but you really want PRR or maybe Ron to give you the good oil. there should be somewhere in your telephones collection one with a printed circuit diagram included. I think they were mandatory in phone equip here.

[mmessmore]

While searching on how to make a 555 oscillator, I found this at the same local radioshack:



It's some Arduino module and has DC 5-15V with 1Hz-200kHz frequency. Will it suffice for this particular project?

I think the module would put you at a bit of a disadvantage over just a chip.  It's likely opinionated to do Arduino-y things, and also probably pretty expensive.  555s are super cheap if you can order from Mouser, Digikey, etc. and pretty easy to use.  For this, even a pack of dubious chips from Amazon or eBay would probably be fine.

I've done a lot of dumb stuff with them (like a replica of "The Internet" from The IT Crowd) and IIRC just the data sheet was useful.

[PRR]

The US telephone system generated 90VAC 20Hz at the central office to ring users. Ringer-voltage is a major headache in small telco systems. The original is the hand-crank dynamo but fisher-folk used them up. I have seen geared motors which threw sparks. Choked thyratrons. Transistors made small-office ringers practical and quiet but still expensive.

Every house used to have that contraption wound to a low voltage and with a make/break contact to keep it going, even on DC.
https://www.homedepot.com/p/Newhouse-Hardware-All-Purpose-Wired-Traditional-Doorbell-Chime-APB1/308470489
https://www.1800doorbell.com/dh922-2-and-one-half-inch-wired-buzzer.htm

This should work on 9V DC but may suck more current than a pedal-supply has. And of course "Smart" (spyware) 'bells' are driving good ringers off the market.

[SeneX225]

Update:
I've finally managed to build a 555 timer using this schematic:


(+9V goes to positive of DC jack, output goes to positive on the ringer)

Unfortunately, it didn't work. Even the singular click the ringer did when connected directly to 9V DC doesn't happen anymore.


(Black and yellow wires are grounds from DC jack and the ringer respectively, white is ringer positive and red is DC jack positive)

What could be the problem?

I think it is either:
- My wiring or building, which is entirely possible since I'm not even remotely good at it yet (if so, then how can I diagnose what exactly isn't working?)
Or
- I've got the wrong schematic (I choose this one because it was already translated to stripboard layout)

Any help or suggestions, as always, are highly appreciated.

[antonis]

What could be the problem?

Current..??

[SeneX225]

What could be the problem?

Current..??

I'm using DC 9V 500mA power supply. Could it be that the current is not enough?

Unfortunately I don't have another 9v supply with higher current, but I have a 12V 3.34A one. Will it do?