Biscuit Tin Drums - Electronic Circuits Projects Diagrams Free

elMickotanko · 9th August 2006, 01:13 PM

Hi,

Im trying to make electronic midi drums. Ive got my electronics sorted: A piezo disk into a peak detector op-amp circuit then connected to a pic which sends midi out with its USART. Thats all working fine:

Piezo triggering

Midi activity

My problem lies in that i want to house them in biscuit tins. A big roses tin for a snare, and two other smaller tins for toms. I glued (epoxy) the disks to the undersides of the lids and connected them to a phono socket on the side of the tin. They just dont work right. They work periodically (about 3 in 10 hits). Its so frustrating, i thought this would be the easy part!
The tin where its glued is like those jars or bottles of food where you press the lid and it pops if its already been opened. This doesnt seem good for the disk also as one of the leads fell off after a few presses.

I want it to trigger really easily and reliably so i can drum fast with just my hands

Has anyone used these piezo disks? How did you mount them onto stuff?

The guy who i got the idea from used sheet metal but i thought biscuit tins would be better cos its thinner?

Ive attached my input circuit.

Dr.EM · 9th August 2006, 02:55 PM

I think the problem might be in the using of hands. The piezo usually needs a hard object to hit it to produce a sharp output rise. Mabye you could have the piezo mounted so that when you hit the tin, it flexes and the metal tin hits the piezo. It probably worked on the desk because your finger was driving it against the hard desk top. Try holding it in the air, tap with your finger then with your finger nail, I expect you find greater reliability with the nail.

Alternatively, it is possible you damaged the piezo by hitting it too hard and now it performs unreliably.

phalanx · 9th August 2006, 03:46 PM

Another possibility would be to use strain gauges on the tins. You could very easily convert the whole system to be pressure sensitive too.

Strain gauges are ultra thin and can be bonded easily to your drum surface.

Rolf · 9th August 2006, 04:17 PM

[quote=elMickotanko]Hi,

Im trying to make electronic midi drums. Ive got my electronics sorted: A piezo disk into a peak detector op-amp circuit then connected to a pic which sends midi out with its USART. Thats all working fine:

Piezo triggering

Midi activity

My problem lies in that i want to house them in biscuit tins. A big roses tin for a snare, and two other smaller tins for toms. I glued (epoxy) the disks to the undersides of the lids and connected them to a phono socket on the side of the tin. They just dont work right. They work periodically (about 3 in 10 hits). Its so frustrating, i thought this would be the easy part!
{snip}QUOTE]

I newer had any luck using epoxy on metal and especially metal that is flexed. After all epoxy is hard and brittle, it is better to use silicone that stays flexible and bonds very well to most metals.

elMickotanko · 10th August 2006, 10:55 AM

Thanks for your ideas.

I would prefer to use the piezos cos i can get them easily from my work, but i dont know where to get strain gauges. I could try a sheet of aluminium which would flex so it wouldnt damage the disk as much, and use silicon?

What do commercial drum pads like the akai MPD16 use?

Mick.

philba · 10th August 2006, 06:04 PM

thinking about it, I bet the tin (steel, I suspect) is spreading the force out over a larger area, When you tapped the piezo with your finger, the force was concentrated in a smaller area. maybe you could make a sandwich with a small circle of, say, rubber that is about the diameter of your finger in between the tin surface and piezo. When you hit the tin, this would concentrate the force into a smaller area on the piezo. I'd use a circle of plywood or mdf to mount the piezo and position it just below the tin surface with the rubber/plastic/whatever disk in the right spot so it makes contact.

You might be able to detect different forces and generate different effects analogous to the different sounds you get depending on where you hit the surface of a drum.

Roff · 10th August 2006, 06:54 PM

Try adding some gain. The circuit below has a maximum gain of 11.

elMickotanko · 10th August 2006, 08:13 PM

Quote:

Originally Posted by philba

thinking about it, I bet the tin (steel, I suspect) is spreading the force out over a larger area, When you tapped the piezo with your finger, the force was concentrated in a smaller area. maybe you could make a sandwich with a small circle of, say, rubber that is about the diameter of your finger in between the tin surface and piezo. When you hit the tin, this would concentrate the force into a smaller area on the piezo. I'd use a circle of plywood or mdf to mount the piezo and position it just below the tin surface with the rubber/plastic/whatever disk in the right spot so it makes contact.

You might be able to detect different forces and generate different effects analogous to the different sounds you get depending on where you hit the surface of a drum.

Thanks, ill try that. That makes a lot of sense. I've thought about the different tones depending where the drum is hit. I suppose with one piezo I would have to sacrifice velocity for this.

For now i just want to get it working. im transmitting a set velocity of 100.

Thanks Ron, i'll try putting in the gain aswell. I've already housed the electronics into a neat box cos i thought it was working

. Its annoying but im learning i suppose.

Dr.EM · 10th August 2006, 08:49 PM

Velocity sensitivity is definately possible with single piezo elements. My cheap electric drum set has quite large diameter piezo discs stuck onto pretty thick steel plates (around 1.5mm thick, doesn't flex at all) and this is coated in rubber on top. It has full velocity sensitivity.

**Nigel Goodwin** · 10th August 2006, 08:55 PM

Quote:

Originally Posted by Dr.EM

Velocity sensitivity is definately possible with single piezo elements. My cheap electric drum set has quite large diameter piezo discs stuck onto pretty thick steel plates (around 1.5mm thick, doesn't flex at all) and this is coated in rubber on top. It has full velocity sensitivity.

That sounds like a FAR better solution, a biscuit tin is thin and crappy!, it will deform when struck and probably break the piezo? (and sound like rubbish).

elMickotanko · 19th August 2006, 08:25 PM

Quote:

Originally Posted by Nigel Goodwin

That sounds like a FAR better solution, a biscuit tin is thin and crappy!, it will deform when struck and probably break the piezo? (and sound like rubbish).

It would look good on stage playing a full set of biscuit tins though!:cool:

Ive tried gluing one on the underside of a proper metal plate, and adding the gain. This has helped a bit, it triggers ok when i tap the ceramic, but its still no good when tapping the other side. Can i just keep increasing the gain until it triggers by hand?

ps. where can i get some rubber

?? I tried glueing a mouse mat to my biscuit tins but it looked crap.

Dr.EM · 19th August 2006, 08:42 PM

Hand triggering is quite difficult. I'd hurt my fingers trying to get anything out of my set without sticks. You may just be able to increase the gain, but i'm not sure it'll be reliable then (my set sometimes false triggers, I think it is due to static build up)

elMickotanko · 15th September 2006, 02:31 PM

Hi,
Still having problems with this.

Does anyone know what commercial 'trigger pads' use? ones that trigger by hand.

Quote:

Originally Posted by phalanx

Another possibility would be to use strain gauges on the tins. You could very easily convert the whole system to be pressure sensitive too.

Strain gauges are ultra thin and can be bonded easily to your drum surface.

Where can I get strain gauges cheaply, all the places i found on the net are £30 upwards? Is there anything i could hack to get them? Or FSRs?

Rolf · 15th September 2006, 03:17 PM

Quote:

Originally Posted by elMickotanko

Hi,

Im trying to make electronic midi drums. Ive got my electronics sorted: A piezo disk into a peak detector op-amp circuit then connected to a pic which sends midi out with its USART. Thats all working fine:

Piezo triggering

Midi activity

My problem lies in that i want to house them in biscuit tins. A big roses tin for a snare, and two other smaller tins for toms. I glued (epoxy) the disks to the undersides of the lids and connected them to a phono socket on the side of the tin. They just dont work right. They work periodically (about 3 in 10 hits). Its so frustrating, i thought this would be the easy part!
The tin where its glued is like those jars or bottles of food where you press the lid and it pops if its already been opened. This doesnt seem good for the disk also as one of the leads fell off after a few presses.

I want it to trigger really easily and reliably so i can drum fast with just my hands

Has anyone used these piezo disks? How did you mount them onto stuff?

The guy who i got the idea from used sheet metal but i thought biscuit tins would be better cos its thinner?

Ive attached my input circuit.

Long time since I worked with op-amps, but why the diode? Check the input to the amp with an oscilloscope, DC coupled, before during and after you do your drumming. Seems like you will have a voltage shift due to the diode and the R-C time constant. Maybe substitute a cap. for the diode, if anything is needed at all.

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9th August 2006, 02:55 PM	(permalink)
Dr.EM	I think the problem might be in the using of hands. The piezo usually needs a hard object to hit it to produce a sharp output rise. Mabye you could have the piezo mounted so that when you hit the tin, it flexes and the metal tin hits the piezo. It probably worked on the desk because your finger was driving it against the hard desk top. Try holding it in the air, tap with your finger then with your finger nail, I expect you find greater reliability with the nail. Alternatively, it is possible you damaged the piezo by hitting it too hard and now it performs unreliably. __________________ Angry!? I'm absolutely electrolytic! Will have to make do with myspace now I guess...

9th August 2006, 03:46 PM	(permalink)
phalanx	Another possibility would be to use strain gauges on the tins. You could very easily convert the whole system to be pressure sensitive too. Strain gauges are ultra thin and can be bonded easily to your drum surface.

9th August 2006, 04:17 PM	(permalink)
Rolf	[quote=elMickotanko]Hi, Im trying to make electronic midi drums. Ive got my electronics sorted: A piezo disk into a peak detector op-amp circuit then connected to a pic which sends midi out with its USART. Thats all working fine: Piezo triggering Midi activity My problem lies in that i want to house them in biscuit tins. A big roses tin for a snare, and two other smaller tins for toms. I glued (epoxy) the disks to the undersides of the lids and connected them to a phono socket on the side of the tin. They just dont work right. They work periodically (about 3 in 10 hits). Its so frustrating, i thought this would be the easy part! {snip}QUOTE] I newer had any luck using epoxy on metal and especially metal that is flexed. After all epoxy is hard and brittle, it is better to use silicone that stays flexible and bonds very well to most metals.

10th August 2006, 10:55 AM	(permalink)
elMickotanko	Thanks for your ideas. I would prefer to use the piezos cos i can get them easily from my work, but i dont know where to get strain gauges. I could try a sheet of aluminium which would flex so it wouldnt damage the disk as much, and use silicon? What do commercial drum pads like the akai MPD16 use? Mick. __________________ My Space

10th August 2006, 06:04 PM	(permalink)
philba	thinking about it, I bet the tin (steel, I suspect) is spreading the force out over a larger area, When you tapped the piezo with your finger, the force was concentrated in a smaller area. maybe you could make a sandwich with a small circle of, say, rubber that is about the diameter of your finger in between the tin surface and piezo. When you hit the tin, this would concentrate the force into a smaller area on the piezo. I'd use a circle of plywood or mdf to mount the piezo and position it just below the tin surface with the rubber/plastic/whatever disk in the right spot so it makes contact. You might be able to detect different forces and generate different effects analogous to the different sounds you get depending on where you hit the surface of a drum.

10th August 2006, 08:49 PM	(permalink)
Dr.EM	Velocity sensitivity is definately possible with single piezo elements. My cheap electric drum set has quite large diameter piezo discs stuck onto pretty thick steel plates (around 1.5mm thick, doesn't flex at all) and this is coated in rubber on top. It has full velocity sensitivity. __________________ Angry!? I'm absolutely electrolytic! Will have to make do with myspace now I guess...

19th August 2006, 08:42 PM	(permalink)
Dr.EM	Hand triggering is quite difficult. I'd hurt my fingers trying to get anything out of my set without sticks. You may just be able to increase the gain, but i'm not sure it'll be reliable then (my set sometimes false triggers, I think it is due to static build up) __________________ Angry!? I'm absolutely electrolytic! Will have to make do with myspace now I guess...