Old telephone ringer stompbox

[Rob Strand]

ok, back to the olden days to deliver what worked. The....
Western Electric field Telephone crank magneto / generator.

I remember the old days at the ski hill, where the lift operator at the bottom would use this to contact the operator at the top.
Aah, the good ole days of commutator communication.
(Either crank with yer foot or incorporate a drill motor)

And they generated enough voltage to make you jump!

[Rob Strand]

A more modern angle to the bell pedal is to simply buy a cheap digital recorder module, record the sound of the bell (from an old movie).  Play it back through the amps.  Light weight and it will run off low voltage.

[GibsonGM]

My old man was an engineer at Raytheon. He told me stories about how they used to glue a quarter to a table, connected to a wire passing thru a small hole below it to one of those generators.  Some sucker would always come by and try to snag the quarter, getting a nice zap, LOL.

[Phend]

Maybe this, I think there a circuits that oscillate quickly on off, 
Many different ones are available .

[SeneX225]

There is another way to do this that leaves the poor old 555 in peace.

If you have 60 Hz power, set up a counter to count three positive alternations of voltage then allow the ringer to get current via an SCR.  Then it waits another three pulses and so on.  If you are on 50 Hz power, count the alternations at the output of a bridge rectifier and hit the ringer through the SCR after five counts.  The latter is more generalized because you can use a divide by five / divide by six to get a universal unit that can run on 50 Hz or 60 Hz.  You may have to use a transformer or resistor to get the correct voltage to the coil.  There is no worry about having the coil see the correct frequency because it is set by the power line.

I understood like a third of the words, whoo-hoo!

This seriously is a case for a pre-packaged solution.
https://www.surplussales.com/Communications/Comms-1.html
Ringing Generator  20 Hz (TEL) TA182/U  $9

Unfortunately, shipping from the US isn't an option for me. I've tried to find something similar in this part of the globe but with no luck.

ok, back to the olden days to deliver what worked. The....
Western Electric field Telephone crank magneto / generator.

I remember the old days at the ski hill, where the lift operator at the bottom would use this to contact the operator at the top.
Aah, the good ole days of commutator communication.
(Either crank with yer foot or incorporate a drill motor)

I can imagine bringing this thing up on a stage. It would certainly be impressive!

A more modern angle to the bell pedal is to simply buy a cheap digital recorder module, record the sound of the bell (from an old movie).  Play it back through the amps.  Light weight and it will run off low voltage.

Yes, either this way or getting a simple piezo ringer (which, as I understand, would work off 9V just fine) would be definitely easier, but the aim of this project isn't to just get a phone ringer stompbox, but find a use for that bell, because otherwise it will just end up in the waste pile.

[SeneX225]

After the last embarrassing failure I've attempted converting the schematic to breadboard again. This time, surprisingly, the oscillator works (although I've about zero clue what did I do differently)!

Here's the updated breadboard:


Here's the original schematic (just in case):


Unfortunately, that's it for the good part.

I've tried plugging the bell directly into output, then I've tried plugging it through capacitors as Rob suggested (a bunch of them: 100uF electro and 10, 100, 33 and 330nf firm). I've also tried different voltages: 9V, 12V and 14V. The ringer doesn't work however I spin it.

Are we back as square one?

[PRR]

FWIW: your (most) ringer is "biased". It wants to lay one way until a rather large signal forces it both ways. This reduces stray ringer-dink on loud speech and also line transients (including nearby lightning). It may want to ring proper with '555 at max voltage, bell tried both ways, and lightly pressing the armature (as you already noted).

[SeneX225]

Small update: I've tried adding the current driver from before:

See this and look up other items related to "555 transistor drive load) for more!   https://www.youtube.com/watch?v=wk5AmxGoFAI

It now rings the bell once (under 14V) and the hammer stays in the second position until disconnected from power.

[Rob Strand]

Small update: I've tried adding the current driver from before:

See this and look up other items related to "555 transistor drive load) for more!   https://www.youtube.com/watch?v=wk5AmxGoFAI

It now rings the bell once (under 14V) and the hammer stays in the second position until disconnected from power.

It won't work like that.

The way to do it with a transistor was posted in reply #49.

https://www.diystompboxes.com/smfforum/index.php?topic=130362.msg1266795#msg1266795

[SeneX225]

It won't work like that.

The way to do it with a transistor was posted in reply #49.

https://www.diystompboxes.com/smfforum/index.php?topic=130362.msg1266795#msg1266795

I glanced over it due to sheer incomprehension and I am happy to announce that I still don't understand almost anything in there!



Please, bear with me.



What are V1 and V2? My blindfolded-in-a-forest research says it's something for measuring current, but I am very not sure.

I think I understand that L1 is a coil with induction rating of 16H. Problem is that I've never made a coil ever.

And the last one insofar: where does the 555 timer come in?

[Phend]

Boy it sure sounds like you have a dead ringer.
Try this.
https://www.analog.com/en/technical-articles/lt1684-solves-global-ringing-problem.html

[Rob Strand]

I glanced over it due to sheer incomprehension and I am happy to announce that I still don't understand almost anything in there!

Please, bear with me.



What are V1 and V2? My blindfolded-in-a-forest research says it's something for measuring current, but I am very not sure.

I think I understand that L1 is a coil with induction rating of 16H. Problem is that I've never made a coil ever.

And the last one insofar: where does the 555 timer come in?

V1 is the output (pin 3) of the NE555 circuit you have already built.   Hopefully around 20Hz to 25Hz.

V2 can be the 14V power supply you already have.

L1 and R1 both represent the bell. They aren't parts, that's what a bell looks like (a coil with some resistance).  So the bell is wired to VCC and VBELL.

C1 is a cap you can tune.  You can use 100uF with the + terminal of the cap at the bell and the - terminal of the cap at the collector of the transistor.  However, if you tune the value (with smaller values) you might get more output - which I suspect would help.

Overall it's not a lot different to what you have done by following the video.   The transistor is wired differently though.

[SeneX225]

V1 is the output (pin 3) of the NE555 circuit you have already built.   Hopefully around 20Hz to 25Hz.

V2 can be the 14V power supply you already have.

L1 and R1 both represent the bell. They aren't parts, that's what a bell looks like (a coil with some resistance).  So the bell is wired to VCC and VBELL.

C1 is a cap you can tune.  You can use 100uF with the + terminal of the cap at the bell and the - terminal of the cap at the collector of the transistor.  However, if you tune the value (with smaller values) you might get more output - which I suspect would help.

Overall it's not a lot different to what you have done by following the video.   The transistor is wired differently though.

Thank you! It is much, much clearer now.

Here's an updated schematic:



C1 is a 100uF electrolyte capacitor.

It does the same thing as the previous iteration, i.e. slams the hammer once and keeps it in "activated" position. Also, I've noticed that a LED connected between bell output and ground stays on even if 9V power supply is disconnected.

Is the layout correct? If yes, do I now need to experiment with capacitor value?

[Rob Strand]

Is the layout correct? If yes, do I now need to experiment with capacitor value?

Looks OK.

Yes try:
- remove D1 (and 1k1 + 2k2).  These parts may be affecting operation.  You can put them back after it works if you wish.
- try reducing the 470 ohm, to 220 ohm
- play with cap value

[SeneX225]

Update, apologies for the delay.

I've pulled out the diode and resistors, reduced 470 Ohm one to 270 Ohm and tried a bunch of capacitor values and types combinations (electrolytes and films from 0.01uF to 100uF) connected in sequence. However, no matter what is changed, there's still only one click and sticky hammer.

Now I suspect that my layout is indeed faulty because bell is wired almost directly into 14V DC input. If I shift its ground wire further to the right or on 9V power line I get no ring at all.

[Rob Strand]

Well if you have a multimeter set it to DC an measure the voltage on pin 3 of the NE555 it will be a about 6V, perhaps a little jittery.

Another test is to get a 1k resistor an connect it in series with a speaker then connect that series combination from pin 3 of the the NE555 to ground, or from pin 3 if the NE555 to +14V; try both.   You should get a clicky/buzzy  20Hz coming out.

[SeneX225]

Well if you have a multimeter set it to DC an measure the voltage on pin 3 of the NE555 it will be a about 6V, perhaps a little jittery.

Multimeter shows 3,7V on pin 3 from 9V power supply, no jittering.

Another test is to get a 1k resistor an connect it in series with a speaker then connect that series combination from pin 3 of the the NE555 to ground, or from pin 3 if the NE555 to +14V; try both.   You should get a clicky/buzzy  20Hz coming out.

Did that, as well, and the 20Hz buzz is coming out.

I can assume there's a power loss going on somewhere (although I'm not sure, naturally). What could be wrong?

[Rob Strand]

I can assume there's a power loss going on somewhere (although I'm not sure, naturally). What could be wrong?

I'm not sure what's wrong.  Your NE555 output looks OK for a 9V supply.  20Hz buzz is a good sign too.  What about measuring the AC voltage across the Bell, with and without the series cap?

I guess the problem is we don't have known good AC voltage source to test the bell with correct voltages.  The circuits we are using are below the "official" voltage spec so we don't know if it's the bell, bell adjusted wrong, or the simple circuits we are using aren't good enough.

Maybe you can wire 2x9VAC supplies in series and connect it directly to the bell, that will give you 18V AC.  18VAC is still low but it's better than 9VAC. You need to connect them the correct way around so the AC voltages add - best to check with a DMM on AC volts.   You could also try putting a capacitor in series with the bell, but you will need a smaller cap since we are now at 50/60Hz instead of 20Hz.  Now the cap must be non-polar or poly because we have an AC source.   50Hz will not sound right.   It's only something to try, and at the end of the day a bit of fumbling in the dark with a AC voltage less than the spec.

Do you have any other AC supplies?   

[SeneX225]

You could also try putting a capacitor in series with the bell, but you will need a smaller cap since we are now at 50/60Hz instead of 20Hz.  Now the cap must be non-polar or poly because we have an AC source.   50Hz will not sound right.   It's only something to try, and at the end of the day a bit of fumbling in the dark with a AC voltage less than the spec.

That absolutely worked! I've plugged bell in 9VAC supply (the only AC one I have) and tried a bunch of different film capacitors between power and bell's "+" terminal, and with 1uF it rings on it's own!

I don't even!

I want to thank everyone involved and you, Rob, especifically for getting through this with me! I learned a fair lot of cool stuff during this ordeal!

Now, only thing left to do is to put a sub-speaker into this thing!

[Phend]

Great, you got it working.
time to set up a "party line",
us old ones might remember those, 2 long, one short,
you better not be listening in on the neighbors gossip !