beef-up an "ultrasonic" amplifier

[Dave]

I have a cheapo ultrasonic pest repeller thing that's just an osc/amp + small
speaker. What I'd like to do is remove the speaker and feed the signal into a
more powerful amp then use that to drive a tweeter. The freq. is about 25-30kHz.
Has someone got a *simple) circuit I can use to do this please? I only have a
multimeter (no 'scope) so I can't see if it's working. I don't want to build the
osc. from scratch because, as I say, I have no 'scope to see it's actually
working.
tia

 

[Joerg]

Hi Dave,

Please mind dogs, pets and wildlife in your neighborhood. They can often hear this
range and to them it may sound like a car alarm constantly running in your living
room would to you.

Regards, Joerg

 

[Ron Hubbard]

I have a cheapo ultrasonic pest repeller thing that's just an osc/amp + small
speaker. What I'd like to do is remove the speaker and feed the signal into a
more powerful amp then use that to drive a tweeter. The freq. is about 25-30kHz.
Has someone got a *simple) circuit I can use to do this please? I only have a
multimeter (no 'scope) so I can't see if it's working. I don't want to build the
osc. from scratch because, as I say, I have no 'scope to see it's actually
working.
tia

Dave, you might try connecting the output of your pest repellor
into the input of a LM384 amplifier. That should give you several
watts of acoustic power.

Ron

 

[Terry Pinnell]

I have a cheapo ultrasonic pest repeller thing that's just an osc/amp + small
speaker. What I'd like to do is remove the speaker and feed the signal into a
more powerful amp then use that to drive a tweeter. The freq. is about 25-30kHz.
Has someone got a *simple) circuit I can use to do this please? I only have a
multimeter (no 'scope) so I can't see if it's working. I don't want to build the
osc. from scratch because, as I say, I have no 'scope to see it's actually
working.
tia

See this recent thread.

To: Newsgroups: sci.electronics.basics
Subject: Re: Need ultrasonic sound
Date: Wed, 28 Apr 2004 14:12:13 +0100
Message-ID: <[email protected]>

The 'Dazer' I mentioned has now arrived. It's very small and powered
by a single 9V PP3. So, assuming it really is effective (and there are
many apparently genuine endorsements), I'm guessing that the
significant difference to my DIY design (18V, and rather larger piezo)
is as Soeren implied, namely the need for an inductor to get
resonance.

I'll open it up soon and report back. But I anticipate still needing
an answer to a question to which I've so far seen no thorough reply:
how to *measure* the output power? (Or calculate it reliably.)