Low voltage / low current sound generation

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I'd like to add a low voltage (3 V) low current
(<0.5mA) tone generator to a battery powered
circuit. Does not need to be very loud, just
enough to draw attention from an ear that is
about 2 feet distant.

My ideal solution is a 3-terminal device -
digital on/off, +Vcc, Gnd - that emits a tone
when the digital input is "on". But I cant seem
to find such a device.

Do they exist, or do I need to find a small piezo
and put a drive circuit around it?

Thanks for any help.

 

[David L. Jones]

I'd like to add a low voltage (3 V) low current
(<0.5mA) tone generator to a battery powered
circuit. Does not need to be very loud, just
enough to draw attention from an ear that is
about 2 feet distant.

My ideal solution is a 3-terminal device -
digital on/off, +Vcc, Gnd - that emits a tone
when the digital input is "on". But I cant seem
to find such a device.

Do they exist, or do I need to find a small piezo
and put a drive circuit around it?

Thanks for any help.

Farnell 500-2989 buzzer is rated for 1.3mA at 3V operation.
Not the 0.5mA you are after, but not too far off either. You could try
limiting the current in some fashion.

Dave

 

[Spehro Pefhany]

Farnell 500-2989 buzzer is rated for 1.3mA at 3V operation.
Not the 0.5mA you are after, but not too far off either. You could try
limiting the current in some fashion.

Dave

Or operate it at a 1/3 duty cycle (eg. 0.25 second on, 0.5 second
off).


Best regards,
Spehro Pefhany

 

[Rich Grise]

I'd like to add a low voltage (3 V) low current (<0.5mA) tone generator to
a battery powered circuit. Does not need to be very loud, just enough to
draw attention from an ear that is about 2 feet distant.

My ideal solution is a 3-terminal device - digital on/off, +Vcc, Gnd -
that emits a tone when the digital input is "on". But I cant seem to find
such a device.

Do they exist, or do I need to find a small piezo and put a drive circuit
around it?

Thanks for any help.

You could take a look at the Sonalert catalog:

http://www.mallory-sonalert.com/catalog_start.htm

They can be a little pricey, but they're way easy to use - just give
them volts, and they beep.

Good Luck!
Rich

 

[lslomer]

You could take a look at the Sonalert catalog:

http://www.mallory-sonalert.com/catalog_start.htm

They can be a little pricey, but they're way easy to use - just give
them volts, and they beep.

Yes, there are some winners in there, thanks.

I also found a <1mA device that works with a square wave
at 1-20V p-p - Projects Unlimited M/N AT-17.

Thansk for all the pointers.