Driving ultra sonic transducer? - Page 1
Forum section: electronics / beginners

author: AcHmed99
author_rank: Contributor
timestamp: September 23, 2013, 01:46:08 pm
content: I have mice getting in my garage. I think they are squeezing in between the door rubber insulation and concrete. I have the door closed as tight as possible and sealed around the frame. Mice can however fit through a hole the size of a dime. I’ve been trapping the little bastards but I’ve been looking into something that will make my garage not appealing. I'm trying moth balls now. I’ve read about ultrasonic rodent repellers and some people swear by them while some claim they don’t work.I was looking at some ultrasonic transducers at Newark and found a couple theMCPCT-G5800-4143for example seems to be the most powerful from the limited information I can find. Could anyone who used something similar answer a couple of questions?How can you determine the maximum range?Is the max range achievable through a wide frequency range 40-50kHz?Do you need to supply the max voltage to get the most power out? In the case of the multi-comp one its 90V.Does anyone know of a transducer that would be effective over 40-50kHz range and give a meter or so range.Whats a typical drive circuit? Hbridge?Has anyone tried ultra sonic emitters for rodent deterrent and does it work?I’ve been trying to find a brief summary of these things and haven’t had any luck. If anyone who’s used these can point me to one it would be appreciated.

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: September 23, 2013, 02:21:03 pm
content: You must have missed this one.http://www.eevblog.com/2011/08/01/eevblog-191-mouse-trap-triggering-2/Sorry I am not actually going to answer your question but:Are they nesting there or there for food?Either way I find you reduce the food and reduce the access, I have a sliding door on our pantry that they can't get past. They are not magic. Make life hard for them and they will leave.We got a rat recently though, ran over my mother inlaw's feet at lunch one day, had to laugh.

author: Bored@Work
author_rank: Super Contributor
timestamp: September 23, 2013, 03:06:06 pm
content: A cat is not an option?

author: uoficowboy
author_rank: Regular Contributor
timestamp: September 23, 2013, 04:15:46 pm
content: Quote from: AcHmed99 on September 23, 2013, 01:46:08 pmHard to determine max range - you need to know at what dba (dbs with respect to 1 pascal) is effective for your furry friends.Typically yes, for max power you want max voltage. It's possible there are exceptions but I'm not aware of them.Not sure about typical drive circuits for a ultrasonic transducer - an H bridge would work but you could try only driving it with a single ended square wave (thus requiring just one FET).Haven't tried this myself.I worry that most ultrasonic transducers are very directional. Directionality is not super awesome. I also worry that this could drive your dog crazy, as dogs can often hear past 40KHz.

author: SeanB
author_rank: Super Contributor
timestamp: September 23, 2013, 05:47:22 pm
content: Simplest way to drive them is to use a class c amplifier and make the transducer part of a LC resonant circuit at around 50kHz. Measure C of the transducer and select a L to get resonance. Then use a 400v or higher rated transistor or MOSFET and drive it with narrow pulses at the required repetition frequency. This then will ring and generate a high voltage sine wave across the transducer ( you need the 400v device so it does not break down) that drives it at max power. Input can be around 12V from a battery. Cheap and easy to make using a 555 timer for the oscillator and another with a slow ramp driving the control voltage input of the first to drive the frequency through a limited range. If you want extra just feed the power wires and replicate the circuit so they will generate a varying annoying tone the mice will dislike. Seems to be working by me, though there i have rats the size of small cats. Simplest source of the transducers is PA piezo tweeters, the ones with a horn designed to be attached to a band speaker to give a beam of high frequency sound to complement the thump of the bass. not the most linear, but they do handle 100V of input quite well.