Electronics - adjustable volume beeper?

[prv]

As part of the new electronics on the new boat, I need an alarm buzzer or beeper which can be adjusted from very quiet (to attract the attention of someone on watch without waking everybody up) to rather loud (to wake people up who are fast asleep). This adjustment should be via a rotating potentiometer or similar device - as I've already sent the panel away to be engraved and cut including a hole for a volume knob.

I assumed I could just put a pot in series with normal buzzer like http://www.ebay.co.uk/itm/proops-Mi...al_Components_Supplies_ET&hash=item19d8b2b672 , but this doesn't really work. At the loud end of the scale it's ok, but as you turn the pot it suddenly goes from still fairly loud to silent, presumably as the voltage drops below a crucial level needed to sustain some kind of vibration inside the box. Same when you start low and turn it up - you get nothing, a slight whine, then loud. Clearly this kind of buzzer is not suitable for volume adjustment in this way.

Any ideas for one that is? Or some other approach? I want to keep any circuit as simple as possible, and don't want to spend much. The supply to the panel is 12v.

Cheers,

Pete

 

[elton]

Are you using a logarithmic pot or linear? If it's doing that with a linear, try a logarithmic; your ears have a logarithmic response.

 

[William_H]

Many alarm type buzzers use a piezo electric panel which I imagine is your problem. A siren or buzzer type circuit using a small load speaker would be far more easily controlled in volume. Look for a kit for an alarm that uses a speaker. good luck olewill

 

[elton]

Many alarm type buzzers use a piezo electric panel which I imagine is your problem. A siren or buzzer type circuit using a small load speaker would be far more easily controlled in volume. Look for a kit for an alarm that uses a speaker. good luck olewill

Can't disagree with that.

 

[prv]

Are you using a logarithmic pot or linear? If it's doing that with a linear, try a logarithmic; your ears have a logarithmic response.

I've tried both, and various ratings. It is as Will suggests - there's either enough to vibrate the piezo or there isn't.

Pete

 

[prv]

Look for a kit for an alarm that uses a speaker.

That was my thought too, but strangely I can't seem to find any. Sure they existed when I was younger, but now the nearest equivalent "learning basic soldering" kits make either steam engine noises or fart noises. Can't find any that make a sensible sound to use as an alarm.

Pete

 

[GrahamM376]

2 x piezos, one high volume and one low with changeover switch?

 

[prv]

2 x piezos, one high volume and one low with changeover switch?

Panel already has a space marked "alarm volume" with a rotary increasing symbol.

Good lateral thinking though

Pete

 

[rogerthebodger]

Any one of there do you

http://www.maplin.co.uk/leisure/electronic-kits/sound-kits

 

[nigelmercier]

Panel already has a space marked "alarm volume" with a rotary increasing symbol.

You could install a rotary switch perhaps, with some resistors?

 

[prv]

You could install a rotary switch perhaps, with some resistors?

To achieve what? I can already vary the resistance, that's what the potentiometer does

The problem is that it turns out varying resistance doesn't really work to vary loudness of buzzers.

Pete

 

[prv]

Any one of there do you

http://www.maplin.co.uk/leisure/electronic-kits/sound-kits

Which? The machine gun? Police siren? Steam engine?

Pete

 

[rogerthebodger]

What ever turns you on.

In fact a simple 555 timer based oscillator and audio amp would do the job

 

[GrahamM376]

Panel already has a space marked "alarm volume" with a rotary increasing symbol.

Good lateral thinking though

Pete

OK then, rotary 2 way switch.

 

[earlybird]

Can you fit 2 buzzers, one loud, one quiet, with a changeover rotary switch in your pre-drilled hole?

 

[AntarcticPilot]

Actually, the steam engine one might be quite good. White noise (which is what I guess the "steam engine" sound is made from) is actually more readily located than sirens or other sounds. You'll note that a lot of emergency vehicles now issue bursts of white noise along with the blues and twos, as that makes it easier for other drivers to tell where they're coming from. So how about using the steam engine sound as your "regular" alarm, with the whistle cutting in if it isn't reset within some period? I'm sure someone familar with electronics could suggest how to modify the circuit - perhaps even making the "speed" of the "choo-choo" noises increase the longer the alarm is on?

Which? The machine gun? Police siren? Steam engine?

Pete

 

[rogerthebodger]

if it isn't reset within some period I would have the machine gun sound to wake the crew up quicker.

 

[prv]

how about using the steam engine sound as your "regular" alarm, with the whistle cutting in if it isn't reset within some period?

Trouble is it's all a bit complicated, where I really just wanted to connect a light and a buzzer via the "external alarm" relay terminals on a piece of kit. I was really hoping someone would suggest a kind of self-contained beeper that does adjust volume with voltage, or failing that a very simple circuit that can be put together "dead bug style" on the terminals on the back of a switch.

Pete

 

[AntarcticPilot]

Trouble is it's all a bit complicated, where I really just wanted to connect a light and a buzzer via the "external alarm" relay terminals on a piece of kit. I was really hoping someone would suggest a kind of self-contained beeper that does adjust volume with voltage, or failing that a very simple circuit that can be put together "dead bug style" on the terminals on the back of a switch.

Pete

I was slightly tongue-in-cheek

However. there is a kit for a function generator which would do exactly what you want, and has an audio output. I'd imagine you'd set it up on the bench using the controls, then just mount it behind the potentiometer.

http://www.maplin.co.uk/function-generator-kit-220045#overview

 

[prv]

However. there is a kit for a function generator which would do exactly what you want, and has an audio output. I'd imagine you'd set it up on the bench using the controls, then just mount it behind the potentiometer.

http://www.maplin.co.uk/function-generator-kit-220045#overview

Still seems like massive overkill. And probably larger than the panel it's attached to.

I did look to see if there are single-chip beeping-tone generators, but they all require to be controlled by a microprocessor, not just power in, sound out. And for anything with a chip I'll need a power supply as well to work with the 12v.

Pete