555 timer dog whistle help

Thread Starter

MDaines

Joined Aug 13, 2010
4
I'm trying to build an ultrasonic dog whistle but am an absolute noob when it comes to reading schematics. I've breadboarded the circuit but I can't get it to work. Attached is a pic of my breadboard and wonder if anyone can tell me where I'm going wrong? Thanks for giving an eager newbie a hand.
 

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Wendy

Joined Mar 24, 2008
22,146
The 555 and I are old friends. I have written a set of tutorials on using them, complete with drawings similar to yours.

I'll review them in more detail when I have time (in a couple of hours). Meanwhile, you might take pictures of your work and post it, we might spot something you missed.

Bill's Index

The 555 Projects

A different variation, not quite what you have but very similar.

555 Hysteretic Oscillator
 
Last edited:

jimkeith

Joined Oct 26, 2011
540
You have your proto board screwed up

Pins 2 must be jumpered to pin 6
Right side of pot does not go to common

10uf coupling cap prob not required as piezo device is open circuit for DC
 

Wendy

Joined Mar 24, 2008
22,146
OK, 2 and 6 are not connected, as mentioned.

Pin 7 is not switched as per your schematic.

You really should have the battery connected directly to the switch, and the switch feeds the power supply buss. This would simplify some of your wiring.
 

SgtWookie

Joined Jul 17, 2007
22,210
Along with everything else mentioned, you have connected your 10uF cap backwards; the stripe on the side of the package indicates the negative side. If you connect an electrolytic cap backwards, you will destroy it very quickly.
 

iONic

Joined Nov 16, 2007
1,650
So, without a REAL picture, all suggestions may be mute as your skills at using the breadboard program may be lacking.

Also, if the circuit is working fine the frequency is as high as 22kHz, you will never know that it is working. You won't be able to hear it. But a dog might. But don't go sticking it up to his ear to try it either.
 

Audioguru

Joined Dec 20, 2007
11,249
Your breadboard photo shows a 4kHz piezo beeper that has a built-in oscillator and runs from a DC voltage.
You need a piezo transducer (it is a speaker). The article used a piezo horn tweeter.
Do not use an ordinary piezo transducer that is in a package tuned to resonate loudly at 4kHz.
 

Thread Starter

MDaines

Joined Aug 13, 2010
4
I live on the other side of the world and it's amazing to wake up to so many people trying to lend a hand! Thank you all for your kindness.

I've taken everyone's suggestions on board and managed to wake my dog up from his morning nap. :D ... Don't worry, I have my dog's interests close to my heart and plan to use this to play a game of hide and seek with him. Attached is a (real) pic of my working circuit.

Out of curiosity, how do I tell what frequency it's playing?
 

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Wendy

Joined Mar 24, 2008
22,146
You could find a friend with a DVM that has a freq counter on it, or buy one. If you have access to an Oscope that would do it too.
 

SgtWookie

Joined Jul 17, 2007
22,210
Try adding another 10nF cap in parallel to the one you have in there.
The frequency output should be roughly 1/2 the original frequency.
You can compare that sound to various tones to find the frequency.
 

Wendy

Joined Mar 24, 2008
22,146
Side note: it also works on teenagers, at a slightly different frequency. When I was in college 37 years ago we had a lot of fun with ultrasonics and driving people crazy.
 

SgtWookie

Joined Jul 17, 2007
22,210
When I was a teenager, the sound of the television HV supply drove me nuts. I couldn't understand why it didn't bother my folks.

Working on supersonic fighter aircraft that had afterburners (F-4J Phantom II's) cured that little problem pretty quickly.
 

Wendy

Joined Mar 24, 2008
22,146
Yeah, it did it for my Dad too (air force mechanic). It obviously bothered him, so he denied it. I figured out pretty quickly he couldn't hear specific frequencies.
 
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