Sound sensor for oscilloscope.

Hi.

Couple of years ago i was in "training" that was a promotion of tools and equipment.

One thing that i noticed was soundsensor for oscilloscope. It had stethoscope style tip,
you just stick the tip whatewer you wanted to "listen"
Ie. fuel injector.

You could see the injector needle movement. That got my attention because ie. Megasquirt settings requires injector opening and closing times.

So, has anyone diy on of these or seen them sold somewhere?
Suggestions?

I put a bolt through the eyelet of a knocksensor. The bolt is welded to a 12 inch push rod and the sensor connects to the scope. This setup is great to capture noise, vibration, knock of many kids and frequencies. I'll upload a picture of the device later so you get an idea...

You also may take any simple piezo sensor, put it in some kind of appropriate housing and connect it to the scope, AC-coupled.

The actual pintle movement (which gives you the actual opening time of an injector) is observable by scoping voltage and amperage: If you really blow up the voltage waveform it allows even for identfying the injector opening, depends on your scope....

I was thinking using a knock sensor and get the idea. Have few laying around.
I suspected that the frequency range might be too narrow. But if it works for you, i will try it too.

Using sound has advantage, that you dont have to try backprobing in tight spots and it works diesel injectors too(if i recall right, that was demonstrated in the event).

We did a whole lot of tests on this just after the forum moved to the current platform Knock sensors are from ideal because they are highly selective in the frequencies they are tuned to.
www.scannerdanner.com/forum/diagnostic-t...-sensor.html?start=0

A cheap electronic stephoscope will cost less than £20/25$/23 Euro from eBay you will also need a an adaptor to BNC or Banana plug.

www.gunson.co.uk/Product/77109/Automotiv...ectronic-Stethoscope

www.scannerdanner.com/forum/diagnostic-t...sensor.html?start=17

juergen.scholl wrote: I'll upload a picture of the device later so you get an idea...

.

The sensor is from a Mercedes "A-Klasse", around 2004. It works very good over a broad frequency range. I use it for noise, vibration etc. Allows for quick ( physical) injector opening check on GDI fuel rails where the pressure sensor connector isn't easy to access (VW, AUDI 1.4 & 2.0 engines)