Boom-box ambulance

An emergency siren that alerts drivers by making their vehicles vibrate is being tested by doctors in Hampshire, England.The Howler is being used by BASICS Hampshire, a charity made up of 20 volunteer medics who attend about 750 road traffic accidents every year. The Howler sends out low bass sound that makes the car in front "shake".Dr Rob Dawes, a volunteer doctor whose full-time job is as an hospital anaesthetist and military doctor, said people get out of the way quicker when the device is used.He said: "The main problem is on the motorways where people can't hear the sirens or see you, because often they either don't look in the mirrors or they've got the radio on quite loud."What this new siren aims to do is, because they can't see you and they can't hear you, we hope that they'll be able to feel you." BBC Story.

Topic by Kiteman   |  last reply

​HELP! Looking for mechanical engineering advice in building a multiplier/compounding gearbox for a hand crank siren project

HELP! I have a project I'm working on that involves making a hand cranked mini air-raid siren utilizing a 12v generator and a 12v siren. I've done a proof of concept rig where I direct wired the siren to the generator and then used a drill to generate enough RPM on the shaft to get the noise I want. Problem is, I'd like to make this entirely manual and will be adding a crank handle once I get the housing built...which means, I need a way to seriously up my RPM. I've done research into building multiplier gear boxes and compound gear trains and pinions and everything in between, but am going to confess that while I'm obsessed with DIY projects, this one is exceeding my engineering knowledge. I am at a loss for how best to approach this build. What ratio would you suggest? 40:1? 50:1? Does anyone have experience building gear boxes that would be ok emailing me with their advice? The input for my generator is a 20 tooth gear (please don't laugh if I'm totally messing up all the nomenclature...most of my life experience comes from writing and baking and a very short (failed) stint as an EE...this is a totally new world for me.) and I got this information from another sub: it’s a 3600 rpm motor so 60/sec. I think the fastest I would want to crank is 2/sec, so, 30:1 gear box sounds about right. With a nice long crank handle a 50:1 should also work nicely. 10:1 is too slow. Ideally (and this might be where it gets really tricky) I'd like it to all fit into a space that's about 5"X3"X3, not including the siren (I can run that further out, using the leads).I'm attaching a photo of the original proof of concept wire up that I did...and don't worry, I know there are exposed wires, I fully plan on isolating the wires, insulating the whole thing and installing the proper resistors. Here is a link to the generator: is a link to the siren: you in advance!

Question by Tye Rannosaurus   |  last reply