How to lower volume on small speaker on intercom handset without volume control? - Page 1
Forum section: electronics / beginners

author: saflyfish
author_rank: Contributor
timestamp: August 26, 2025, 12:21:01 pm
content: My home intercom doesnt have a volume control.When someone buzzes me its so loud it freaks me out...Is there anything i can do to lower the volume?

author: inse
author_rank: Super Contributor
timestamp: August 26, 2025, 12:25:44 pm
content: Series resistor or anti serial zener diodes as limiter parallel to the speaker.Alternatively some foam material in front of the membrane.

author: themadhippy
author_rank: Super Contributor
timestamp: August 26, 2025, 12:27:20 pm
content: wrap it in foam

author: inse
author_rank: Super Contributor
timestamp: August 26, 2025, 12:28:41 pm
content: Fill it with spray foam ;-)

author: saflyfish
author_rank: Contributor
timestamp: September 03, 2025, 09:03:44 am
content: Cant cover the speaker as there is only ONE speaker in the unit for ring and listen...

author: SteveThackery
author_rank: Super Contributor
timestamp: September 03, 2025, 09:42:41 am
content: So are you saying the volume is OK for speech, but the buzz is too loud?

author: saflyfish
author_rank: Contributor
timestamp: September 03, 2025, 10:03:03 am
content: yes that is correct

author: inse
author_rank: Super Contributor
timestamp: September 03, 2025, 01:02:06 pm
content: Then anti-serial zener diodes, value to be determined experimentally

author: themadhippy
author_rank: Super Contributor
timestamp: September 03, 2025, 01:13:26 pm
content: complicated method would be a narrow notch filter tuned to the buzzing frequency,but to avoid speech sounding a bit weird you might need to switch it out when talking,or just use a resistor to reduce the level thats switched out for speach

author: SteveThackery
author_rank: Super Contributor
timestamp: September 03, 2025, 08:34:54 pm
content: Most of the suggestions so far will reduce, or limit, both the speech and the buzz, which is not what you want.I think we need to see the schematic to work out how to quieten the buzz, without affecting the speech. What can you provide? If you dont have the schematic, tell us exactly what the device is. Photos of it, including of any labels, would help.

author: Analog Kid
author_rank: Super Contributor
timestamp: September 03, 2025, 08:59:09 pm
content: Wellll, seems to me that if it's just the buzzer that's too loud, the thing to do is to track down the source of the buzzer voltage (probably stepped-down line voltage @ 60 Hz) and reduce that. The buzzer voltage will be separate from the voice output, so reducing it won't affect the voice volume at all.Shouldn't be hard to do, but you'll need either a schematic (which may be difficult or impossible to obtain) or do enough poking around in there to see where the buzzer voltage comes from (trace it from the buzzer switch). Then in that buzzer circuit, probably just insert a simple voltage divider--2 resistors in series with the output being the connection between them--which will reduce the buzzer voltage to a tolerable level.

author: SteveThackery
author_rank: Super Contributor
timestamp: September 04, 2025, 08:17:37 am
content: Quote from: Analog Kid on September 03, 2025, 08:59:09 pmI'm thinking the buzzer isn't actually a physical buzzer, but rather a tone generator that plays through the loudspeaker. Hence it being more complicated. I could well be wrong, of course.

author: Analog Kid
author_rank: Super Contributor
timestamp: September 04, 2025, 08:25:45 am
content: Quote from: SteveThackery on September 04, 2025, 08:17:37 amYes, of course; that's what my answer was based on.The buzzer is probably a tone generator that's fed either to the input of the amplifier or directly to the speaker. I'd guess the former. (Not 60Hz current as I wrote above; probably more like 400Hz.)Still just a matter of following some switch wiring into the circuit to figure out where that signal gets injected, then tone it down a bit with a resistor or two.

author: inse
author_rank: Super Contributor
timestamp: September 04, 2025, 12:04:47 pm
content: Series resistor and a pushbutton to bypass it during intercom?

author: Analog Kid
author_rank: Super Contributor
timestamp: September 04, 2025, 07:47:24 pm
content: Quote from: inse on September 04, 2025, 12:04:47 pmThat would work but would be a pain in the ass to use.

author: inse
author_rank: Super Contributor
timestamp: September 04, 2025, 08:27:06 pm
content: Why?What else would you have to do while talking to a person at the door?Remember we are in the beginners section here, even more reason to stick to the KISS principle.A robust and simple solution

author: Stray Electron
author_rank: Super Contributor
timestamp: September 04, 2025, 08:30:40 pm
content: The gas stations around here have loud BLARING videos that each pumps blasts out directly into the customer's ear as they're filling their cars. I carry a roll of cheap thick duck tape in my truck and I tear off a short section of it and place it over the speaker when I am refilling my vehicle. Other people have taken to smashing the LCD displays but that doesn't really stop the blaring audio. I don't know how long the duct tape stays up on the pump before somebody removes it but I suspect that it's a long time since the sales droids inside never come outside unless they'reforcedto for some reason.

author: Stray Electron
author_rank: Super Contributor
timestamp: September 04, 2025, 08:32:13 pm
content: Quote from: inse on August 26, 2025, 12:28:41 pmI have strongly considered doing that at some of the gasoline stations!

author: Analog Kid
author_rank: Super Contributor
timestamp: September 04, 2025, 09:12:43 pm
content: Quote from: inse on September 04, 2025, 08:27:06 pmBecause it's an inelegant solution.QuoteTrue, but that doesn't mean we should dumb things down excessively.Let's leave your suggestion as a fallback solution in case the OP can't figure out how to reduce the buzzer volume but not the audio.

author: inse
author_rank: Super Contributor
timestamp: September 05, 2025, 05:21:45 am
content: Ok, what about the before mentioned antiserial zener diodes parallel to the speaker? (perhaps a couple of antiparallel small signal diodes will suffice)This way it had been done in the old analog telephone world.(Schematic from Wikipedia)Do you have a possibility to measure the buzzing voltage and the audio signal voltage?Otherwise try and error