» MAKE: NOISE — Discuss this article

Showing messages 1 through 3 of 3.

• Anti-Dog Bite Siren
  You must be logged in to reply.
  
  
  I am very new to electronics, but I have the siren cut open and I would like to know if I can push the frequency of this siren into the ultrasonic range. How much would I need to reduce the voltage and resistance to get the sound past human hearing without burning out the siren? How difficult would it be to wire in an LED so you know it's working if you can't hear it?

  Posted by TSill on May 24, 2011 at 08:34:43 Pacific Time

• higher frequency
  You must be logged in to reply.
  
  
  Because the transducer that makes noise in the siren is not designed to work at ultrasonic frequencies, I don't know how much you'll get out of it, and you'll need an ultrasonic microphone or sensor to find out. This is why I chose not to do that! Still you can get some idea by substituting a series of resistors of different values and seeing how the sound varies. Trial and error is the way you would have to go. As for a "power on" LED you would simply put it across the input to the device (with a series resistor to stop it from burning out). But that will just tell you that the power is on. It won't tell you that the transducer is still working.

  Posted by Charles Platt on May 24, 2011 at 10:16:42 Pacific Time

• Dog behavior...
  You must be logged in to reply.
  
  
  ..be advised that this siren isn't going to do anything you couldn't do yourself and is only going to scare away a dog that's inclined to be scared by something like this, in which case it probably wasn't going to bite you anyway. An aggressive dog, i.e. one that you need to worry about biting you, is equally likely to be spurred to attack by the sound this thing makes.
  
  If you do manage to get a supersonic tone out of this design, there's nothing special about it that repels dogs, it's just another noise to them. Dogs have the ability to tune out sounds that are not important to them. Even if an aggressive dog is not so focused as to ignore the tone, once nothing bad happens in relation to it, it won't even hear it any more.

  Posted by Grizzly Johnson on May 26, 2011 at 11:24:04 Pacific Time