What is this part in a “retro” phone?

Question

I’ve got a recently manufactured “retro” landline phone that I wanted to scavenge some parts from, made in 2012 I think. I’d like to be able to do something with the ringer, which appears a lot simpler and more low power than old rotary phone bell ringers. Anyone seen a motor/actuator like this? Trying to figure out what voltages I’m actually going to be working with. Wondering if I can power this with much smaller AC voltages than typical old phones.

The brass cup screws on over this little motor and you can see in the photos the driver rod which it has on both sides to actuate the bell—I assume it’s one rod/piston/driver… Any idea the part? I cannot find any part numbers on it…. The bell says “Hongfu Sound” which returns very little.

Image 1:

Image 2:

Edit:

Sorry not a retro phone at all, hence the quotations, it’s apparently still for sale below. That’s why I was super curious about the ringer motor because it seems like I could use this more easily with smaller power signals.

https://www.amazon.com/Wild-Wolf-Rotary-Landline-Telephone/dp/B07X5MSPX3/ref=mp_s_a_1_1?qid=1678582582&sr=8-1&srs=14625083011

Answer 1

This is a metal stick (clapper) from a bell.

The stick is ringing the bell and he can move because of this gray magnets on each side and a coil in the inside. The coil is wrapped around the metal stick.

The black and red cable are there for moving the stick against the bell. This is possible DC voltage what is used there. You apply a PWM signal with 50% on and 50% off timing to this red/black cable (black = GND, red is possibly 12V) and this will create the ringing sound.

So is possibly the technical solution of this phone.

You could use an other frequency and make the ringing a bit different if you want.

To drive this bell I would apply a voltage source to it and increase the voltage till the stick is moving out. The current can be high, maybe 1A.

If you want to drive this bell, then add 12V to the red cable and a N-Channel Transistor (MOSFET) to the black cable. (Drain to the black cable, source to GND of the voltage supply and with the gate you can control the current flow)

Driver:

R3 should be much bigger, between 10k Ohm and 100k Ohm would be okay.

Answer 2

It's a solenoid actuator.

...............

Answer 3

Without seeing more of the circuitry (bottom side of the board - ?) it's impossible to say for sure. Just guessing . . .

As above, the ringer is a simple solenoid. The armature oscillates back and forth with a high voltage AC sine wave. The phone company ring voltage is an AC sine wave sitting on a -48 V DC pedestal. C15 removes the DC component, so only the AC waveform reaches the ringer.

The four diodes for a bridge rectifier. They power the audio circuits, not the bell.

A POTS phone line is polarized, and old phones had no active electronics in them, so they worked no matter which way they were connected to the line. Modern phones have transistors, maybe opamps, etc, and these circuits most definitely are polarity-sensitive.

With a bridge between the lines and the electronics, the overall circuit is then polarity independent because the bridge steers the operating current whichever way is necessary for current to move through the circuits.

Here is a link to a typical electronic phone schematic from the 80's.

https://www.next.gr/uploads/135-10235.png