Decrease apartment intercom door buzzer volume

Question

The intercom in my condominium unit (that I own) works well, but is horribly loud. I understand this can be a boon so that I never miss a buzz, but my unit is small enough that the volume cannot be justified. There is no built in volume control.

Since I own my apartment, and we are self-managed, I cannot call a landlord. Perhaps I could call a maintenance company to install a different panel, but in my Googling, I cannot find replacement panels with volume control knobs, so I'm not sure that would help.

The manufacturer of my intercom panel does not seem to actively promote/advertise their intercom products, so I worry there's no obvious replacement.

This is my intercom panel, a Jeron.

I don't want to remove the buzzer completely, or add any glue to dampen the volume. I was hoping I could add a potentiometer or some other device to decrease the volume, but it seems a potentionmeter may be discouraged for this scenario.

Is there any simple solution here? Install a lower capacity speaker? Some sort of resistor that could be installed to decrease the volume? An alternative sort of intercom panel I haven't yet found online?

Answer 1

you need to reduce power to the diaphram. A fixed value resistor is a decent way of doing that.

Cut a white speaker wire, patch it with a resistor, which you can get at radio shack or wherever. Start with matching the speaker ohms (likely 4, 8, or 16) to ~half the volume. a pack of 5 5-10ohms would be good because you can connect them in series to get multiples of 5 or 10 to adjust the volume.

you could replace the speaker with a higher-ohm model as well, they make them in all sizes, so i'm sure you could find a drop-in physical replacement.

A potentiometer might work, but has some complications: most are too high resistance (ex 0-100 ohm), most zeros aren't zero, but rather 5-10 ohms, which steps on your adjustment range a lot. Many pots don't handle very much current either, so you could fry a cheap/small potentiometer, although that's probably not likely.

if you don't want to cut wire, you can "short" the speaker with a resistor, instead of wiring it in series. this reduces the amount or power going to the diaphragm, but wastes power. don't put fewer than 10ohm across if you go that route.

Answer 2

I have the same Jeron unit, and I was messing with it the other day and tried reverse-engineering the circuit.

That little speaker with the flag sticker on it is a special type, with a 45 Ohm coil. The annoying doorbell waveform is a square wave at about 3.5 Vpp, so the total electrical power into the speaker is about 0.25 watt - nothing spectacular.

There are 4 wires that go the wall unit, in order from right to left: (BROWN) door open. (BLACK) common - this functions as ground for the wall unit, but it seems that the whole circiut is isolated and floating, so we call this a "common". (GREEN/WHITE) this is audio in/out for the intercom function. (ORANGE) buzzer signal.

If you put a series resistor in the ORANGE lead, so the doorbell sound is reduced, but the audio drive and microphone functions are undisturbed. Assuming the source is low impedance, a 47 Ohm resistor would cut the power by 6 dB, whence a 100 Ohm resistor would cut the power by 10 dB. The resistor power will be only 65 mW, so you don't need to worry about that all that much.

Disclaimer: I have not myself tried any modifications to this thing, and this post is for entertainment only. Any suggestions for modifications to equipment are purely hypothetical and should never be performed!!! If such modifications are performed despite of this warning to the contrary, the author of this post bears no responsibility whatsoever for whatever the outcome might be.