Sound detector to detect hammer strikes

goom

Senior Member
Yes, vibration detectors are freely available. I just thought that it would be a simple "quick and dirty" means of testing whether monitoring sound board vibrations is a viable technique for detecting hammer strikes (assuming that you have access to a record player). Furthermore it would be non-invasive (to the dulcimer) insofar as it would not affect the soundboard vibration, nor require any fancy mounting (at least for testing the concept).
 

Gramps

Senior Member
I will ask around and see if anybody has seen a record player as a donation to the Rescue Mission
 

hippy

Senior Member
While all the suggestions are useful ideas, I can't help but think the simple microphone and amplifier solution would be cheapest and easiest to get working if one isn't going to use the equivalent of a guitar pickup.
 

The bear

Senior Member
That led me to wonder what the difference is between gramophone & phonograph - I had no clue; think I'll stick with "record player" ;-0
https://english.stackexchange.com/questions/149563/whats-the-difference-between-phonograph-and-gramophone

Gramophone: Any sound-recording device, or device for playing previously-recorded sounds, especially if it uses a flat spinning disk.


Phonograph: Any sound-recording device, or device for playing previously-recorded sounds, especially if it uses a spinning cylinder.
 

Gramps

Senior Member
Here's an update.
We cleaned the strings on the dulcimer with fine sandpaper and connected each string pair between the pin and ground. Using a hammer with fine stranded wire taped on the edge we were getting 99 to 100% positive sequencing.
My wife said I cannot use her gramophone for any experiments so I bought a couple of these:
https://www.amazon.com/SW-420-Normally-Closed-Vibration-Sensor/dp/B01MQFRQRC/ref=asc_df_B01MQFRQRC/?tag=hyprod-20&linkCode=df0&hvadid=193992629021&hvpos=1o3&hvnetw=g&hvrand=8571018602723261895&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9012216&hvtargid=pla-313747041049&psc=1
 

AllyCat

Senior Member
Hi,

Hmm, IMHO that looks like the wrong type of "vibration" sensor. There are references to earthquake, motorcycle/car theft and washine machine (drum unbalanced ?). The "sensor" looks a little like a mercury tilt swich (but probably using something cheaper and safer than mercury).

The circuit diagram lower down in this link shows the sensor shunted by a 100nF capacitor and with a 10k pullup, so it's unlikely to respond to any "audio" frequencies.

As hippy and I have suggested several times now; if you're trying to detect a string of a musical instrument being struck, then the "obvious" method is an audio detector. The waveform shown by hippy in post #106 looks eminently detectable.

Cheers, Alan.
 

premelec

Senior Member
Well this could go on forever... however 100nF x 10K = 10^-3 so probably detects lower audio ok... I think a bandpass filter for the instrument audio range and amplifier put into a clipping shaper circuit should give a nice pulse that could be measured by PULSIN of a PICAXE running high clock speed - and pulse width can be related to pitch... however this circuitry is apparently beyond Gramps' knowledge and I don't know any ready made circuit to suggest...
 

Gramps

Senior Member
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