Comments on: Arduino – making a basic drum machine

By: ychamyuen

ychamyuen — Thu, 19 Apr 2012 00:10:28 +0000

Ok, sorry… the piezo buzzer goes in parallel with the 1 M Ohm Resistor. And that’s because Ohm’s Law V = IR.
When the piezo vibrates, it induces a small current into the 1M Ohm resistor, giving you a decent value of V, to be read by a microcontroller.

By: ychamyuen

ychamyuen — Wed, 18 Apr 2012 23:44:27 +0000

The reading comes from a voltage divider.
The piezo buzzer that changes it resistance value (when pressed) in series with the 1 M Ohm resistor.
Under this arrangement, if one of the resistors is too small (compared to the other), then the change in voltage is not significant and the reading is more difficult.
Since the piezo buzzer handles values around the 1 M Ohm, then it makes sense to use a 1 M Ohm resistor in series with the piezo buzzer.

By: KinoFrost

KinoFrost — Tue, 30 Aug 2011 20:11:43 +0000

Forgive my noobishness after returning to EE after over 10 years (and given I was about 9 at the time) what are those 1M resistors actually for? I see it in every knock sensor diagram but no real explanation is ever given.

By: larry

larry — Wed, 25 Nov 2009 09:35:04 +0000

This is true and perhaps I should have referred to it as a basic electronic drum kit? But the fact is you can record ‘hits’ if I were to hook it up to Processing etc.. and there are a quite few drum machines that let you do the same e.g play a pattern, recording it for looping etc… In fact on most drum machines you can record a loop in real time by setting the tempo and then pressing the various buttons to record, rather than pre-programming them, granted this is pressing buttons and not hitting them, I’ll dig out the model names if you’re interested (think one I used was by Roland). So I actually don’t think that the use of the term ‘drum machine’ is a mis-use. With a keyboard you press a key, not hit it – so I’m using a percussive method as the piezo sensor registers force of impact not a press – the harder I hit, the louder the note.

Course what I would like to do is to take apart the piezo sensor and then build a trigger system for my drum kit (a real one!) to record, etc.. when I play my drums – no idea how I’d do cymbals yet though…

By: Jx

Jx — Wed, 25 Nov 2009 07:10:15 +0000

Wouldn’t this be a basic synthesizer or keyboard? This device plays tonal sounds corresponding to different buttons. A drum machine allows one to sequence a series of rhythmic patterns made up of synthesized or prerecorded drum sounds. It is not normally “played” in real time, but pre-programmed by the user.

By: larry

larry — Thu, 10 Sep 2009 03:11:44 +0000

d’oh!, yes thats a M! I’ll amend that now – cheers for pointing that one out.

By: unwind

unwind — Wed, 02 Sep 2009 18:53:41 +0000

Your parts list says “2x 1Mega Ohm resistor (Brown, Black, Green, Gold) – that’s 1,000,000K Ohms”, but that ‘K’ is probably a typo. 1 MOhm = 1,000,000 Ohm.