Making a noise? (Electronically)

[Tintin]

Well, that's the general idea, but too complex, and it still needs a volume control.

Pot on the speaker?

 

[Tintin]

Pot on the speaker?

Oh dear. Student flashback

 

[nigelmercier]

Pot on the speaker?

No, pot on the input to a transistor stage.

 

[David2452]

You could simply fit a E2S28D panel mount buzzer, they have built in variable volume. http://www.e2s.com/store/products/85-e2s28d-o28mm-buzzers-panel-mount-indicators.aspx

Might or might not go quiet enough for you but worth a look.

 

[nigelmercier]

You could simply fit a E2S28D panel mount buzzer, they have built in variable volume...

The volume is controlled by twisting the aperture on the front, not really very useful in this case.

As I have said, IMO the best solution is a 555 run in astable mode at around 3kHz, with the output feeding an emitter follower via a series capacitor and a logarithmic pot as the volume control, then to a piezo speaker (one that requires an AC drive, adjust 555 to match resonance).

I don't do analogue, so I'm not the best person to advise on values, I suggest you ask in here: http://www.dutchforce.com/~eforum/index.php

Fell free to quote my suggestion, they may even have a simpler solution.

 

[AngusMcDoon]

the YAPP alarm project is spawned?

555 timer in oscillator mode to give a square wave output, capacitor to round it off to sine wave because it sounds nicer, cheap audio op amp with a pot to control the gain, bishboshjobsagoodun.

 

[prv]

As I have said, IMO the best solution is a 555 run in astable mode at around 3kHz, with the output feeding an emitter follower via a series capacitor and a logarithmic pot as the volume control, then to a piezo speaker (one that requires an AC drive, adjust 555 to match resonance).

I think you're right, but while I can solder stuff together according to a plan, I know buggerall about electronics really and am unable to convert that paragraph into a circuit.

Pete

 

[nigelmercier]

I think you're right, but while I can solder stuff together according to a plan, I know buggerall about electronics really and am unable to convert that paragraph into a circuit.

As I said, I suggest you ask in here: http://www.dutchforce.com/~eforum/index.php they are very kind to newbies.

 

[FullCircle]

555 timer in oscillator mode to give a square wave output, capacitor to round it off to sine wave because it sounds nicer, cheap audio op amp with a pot to control the gain, bishboshjobsagoodun.

How much for one o' dem den?

 

[AntarcticPilot]

I too am an electronic ignoramus! However, I did a quick search, and found two circuits that put together ought to do what you want. One generates a suitable beep, beep; the other is a simple circuit to control the volume.

This is the first: http://www.electronic-circuits-diagrams.com/alarmsimages/alarmsckt18.shtml
The second is: http://www.avforums.com/forums/speakers/1200667-speaker-volume-controls.html

HTH!

 

[AngusMcDoon]

How much for one o' dem den?

I dunno, because I'm in Tayvallich at the moment and the only internet is slooooow GPRS. Can't look at hefty websites with pictures like Farnell or RS.

 

[FullCircle]

I dunno, because I'm in Tayvallich at the moment and the only internet is slooooow GPRS. Can't look at hefty websites with pictures like Farnell or RS.

Will wait for quality....

 

[GHA]

http://mobile.maplin.co.uk/module.aspx?moduleno=220043

 

[prv]

http://mobile.maplin.co.uk/module.aspx?moduleno=220043

Perfect!

I spent some time looking for kits and didn't find that one. No idea why not, but it looks just the job together with a piezo speaker.

Thanks.

Pete

 

[AntarcticPilot]

Perfect!

I spent some time looking for kits and didn't find that one. No idea why not, but it looks just the job together with a piezo speaker.

Thanks.

Pete

No volume control - you might have to use the second circuit I posted.

 

[nigelmercier]

No volume control - you might have to use the second circuit I posted.

It won't work, impedances are all wrong. The Maplin kit is just 555 chip with a few other components, just as easy to find a circuit online, or ask in the electronics forum I mentioned.

 

[BruceDanforth]

Why don't you think it will work?

It won't work, impedances are all wrong. The Maplin kit is just 555 chip with a few other components, just as easy to find a circuit online, or ask in the electronics forum I mentioned.

 

[nigelmercier]

Why don't you think it will work?

As I said, the impedances are wrong. A volume control needs to feed a relatively high impedance, not direct to a speaker.

 

[BruceDanforth]

Are you worried the sound of the square waves will distort?

As I said, the impedances are wrong. A volume control needs to feed a relatively high impedance, not direct to a speaker.

 

[prv]

The Maplin kit is just 555 chip with a few other components, just as easy to find a circuit online, or ask in the electronics forum I mentioned.

Equivalent result, yes, but far from "just as easy". I'd have to register on a new forum, engage in a discussion, choose a design, locate the proper components, buy them, convert the circuit to a veroboard layout, cut the tracks appropriately and accurately, then solder it up and hope all the previous steps have been done correctly.

Or I could just pay seven quid, pop the legs through the holes in the ready-made board, quick solder and job done, practically guaranteed to work.

And by the time I've bought the various components for the DIY option, probably on eBay in packs of 20 as smaller quantities aren't economic, there's probably not even much difference in price. Yes, I could then make another 20 for nothing (actually I'd probably need more veroboard), but I don't want another 20 of the things so it's irrelevant.

Pete