[DESIGN] Piezo-Piezo to Piezo-Switch Adaptor (by Keith Raper)

[PFozz]

Piezo/Piezo to Piezo/Switch Adaptor by Keith Raper DON’T MISS THE...

Piezo/Piezo to Piezo/Switch Adaptor
by Keith Raper

DON’T MISS THE UPDATED INFO
BELOW THE ORIGINAL CONTENT 😉

The information provided here is freely available to all for NON-COMMERCIAL purposes only.

The schematics and information are provided ‘as is’, without warranty of any kind.

As everything provided on this website, the author (Keith Raper), EDrum For Free or any other party cannot be held responsible for any damages to yourself, others, or equipment while attempting
any of the projects listed on these pages.

Please use common sense.

---

Many of you and mostly members of the DTXPress Yahoo! group have heard about the “Magic Box” which will allow two pads to use one input on the DTXpress, and also combine two piezos from a single pad into a single piezo and rim switch signal for use on the DTXpress (some non Yamaha dual zone pads use two piezos instead of a single piezo and a rim switch).

As the original “Magic Box” was quite complex, I have come up with a simplified idea which should be within the abilities of anyone who wants to have a go. The components will only cost a few cents and the circuit is “passive” in that it does not use any external power (but has an “active” component).

Here are some schematics for various applications :

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NB : Bear in mind that when combining two pads into one input you can only get one sound at a time (although you can get both if one hit is slightly after the other) so you need to choose your combinations with some thought (ie don’t combine the kick drum, snare or high-hat with anything).

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Example applications :

– Mesh Head dual-trigger (piezo/piezo) to piezo/switch input (Dual mesh toms on the TD-8/TD-6V/DTXPress/…).

– Dual-zone cymbal made of 2 piezos (design by PFozz to come).

– Triple-zone cymbal made of 3 piezos (design by PFozz to come).

– …

For less “rim/edge sensitivity”, reduce the R2 value but DON’T replace it with a wire (100K to 1M is alright).

---

UPDATED (03/2006)
I have now made a PCB and am building up my DTXpander (for a small fee) for people who cannot do it themselves.

I am still happy for people to build their own, and here’s the latest circuit : http://edrum.for.free.fr/static/pictures/KeithRDTXpanderCheapB.pdf

The changes are minor :
1. putting a potentiometer for R1 to adjust sensitivity

2. Schottky diodes to reduce the voltage drop from the piezos (0.3V instead of 0.7V)

3. a jumper to allow one of the diodes to be shorted out.
These changes may help with systems not like my commercial DTXpress kit.

The Schottky diodes will help if the piezo signals are low – I have not noticed any difference with the DTXpress.
The option to bypass one of the diodes can help improve the signal from that pad if the polarity is wrong on the pad – the circuit works best with positive going pulses from the piezo.

Enjoy 😉

Keith Raper

(Key Design Electronics Ltd.)

http://www.kdel.co.uk

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Excellent design, Keith!
Thanx for your contribution 😉
Best.

www.eareckon.com

Piezo/Piezo to Piezo/Switch Adaptor
by Keith Raper

DON’T MISS THE UPDATED INFO
BELOW THE ORIGINAL CONTENT 😉

The information provided here is freely available to all for NON-COMMERCIAL purposes only.

The schematics and information are provided ‘as is’, without warranty of any kind.

As everything provided on this website, the author (Keith Raper), EDrum For Free or any other party cannot be held responsible for any damages to yourself, others, or equipment while attempting
any of the projects listed on these pages.

Please use common sense.

---

Many of you and mostly members of the DTXPress Yahoo! group have heard about the “Magic Box” which will allow two pads to use one input on the DTXpress, and also combine two piezos from a single pad into a single piezo and rim switch signal for use on the DTXpress (some non Yamaha dual zone pads use two piezos instead of a single piezo and a rim switch).

As the original “Magic Box” was quite complex, I have come up with a simplified idea which should be within the abilities of anyone who wants to have a go. The components will only cost a few cents and the circuit is “passive” in that it does not use any external power (but has an “active” component).

Here are some schematics for various applications :

---

NB : Bear in mind that when combining two pads into one input you can only get one sound at a time (although you can get both if one hit is slightly after the other) so you need to choose your combinations with some thought (ie don’t combine the kick drum, snare or high-hat with anything).

---

Example applications :

– Mesh Head dual-trigger (piezo/piezo) to piezo/switch input (Dual mesh toms on the TD-8/TD-6V/DTXPress/…).

– Dual-zone cymbal made of 2 piezos (design by PFozz to come).

– Triple-zone cymbal made of 3 piezos (design by PFozz to come).

– …

For less “rim/edge sensitivity”, reduce the R2 value but DON’T replace it with a wire (100K to 1M is alright).

---

UPDATED (03/2006)
I have now made a PCB and am building up my DTXpander (for a small fee) for people who cannot do it themselves.

I am still happy for people to build their own, and here’s the latest circuit : http://edrum.for.free.fr/static/pictures/KeithRDTXpanderCheapB.pdf

The changes are minor :
1. putting a potentiometer for R1 to adjust sensitivity

2. Schottky diodes to reduce the voltage drop from the piezos (0.3V instead of 0.7V)

3. a jumper to allow one of the diodes to be shorted out.
These changes may help with systems not like my commercial DTXpress kit.

The Schottky diodes will help if the piezo signals are low – I have not noticed any difference with the DTXpress.
The option to bypass one of the diodes can help improve the signal from that pad if the polarity is wrong on the pad – the circuit works best with positive going pulses from the piezo.

Enjoy 😉

Keith Raper

(Key Design Electronics Ltd.)

http://www.kdel.co.uk

---

Excellent design, Keith!
Thanx for your contribution 😉
Best.

www.eareckon.com

Topic

[tazinnuedo]

are you sure that your circuit is alright???? maybe a reversed diode,or  the transistor is reversed… i don’t know…  check your circuit to be sure that’s not this problem…
have you selected the good type of pad in your drum brain? i don’t know if it’s possible on a td6 but on the td10 you can choose what kind of pad you want… (if you select a mono pad on your module and play with a dual pad… you will have only the head sound…) i don’t know how work exactly the input into the module(if the jack’s ring is bypassed or bypassed and linked with the sleeve) when you select a mono pad… and it’s not exactly the same problem than yours  but maybe it will be solved it…
 
francois

[elrules]

I have checked the circuit. Referring to the input pad type. The TD6 can’t assign a different pad type for the rim on a piezo/switch input. It’s obvious you have to choose an stereo pad type for the input in order to “cheat” the module. The types selectable are PD type, PD-8, CY type, CY-8, KD type, KD-8, PD-80R, PD-120, PD-125, RT-7K, RT-5S, and RT-3T.

But it’s not working. I know that with TD-20 and TD-12 the inputs are splittable
just adding a 100k resistor between tip and ring, but for inferior modules, like TD-6 this simple cable is not possible. Has any of you tried this circuits with a TD-6 module?? I need help :'(

[tazinnuedo]

http://www.vdrums.com/forum/showthread.php?t=20504&highlight=padtable
 
look at the jman’s link in the thread… you may got your response…  if i have understood, inputs 5,6,7,8 are splittable in two mono pads, but not input 4.   if you select PD8 you can have rimshot on input4????
 
(on the td10 you can only choose type of pad too and it’s this choose which determines the input’s type (mono or stereo etc…)
 
 

[elrules]

In the TD6 module, inputs 5/6 and 7/8 are splittable with a simple Y cable from stereo jack to two mono jacks. But input 4 and others are not splittable. That is the reason for me to be here posting and trying to get a response. To be able to split an un-splittable input cheating the module. I think this is the purpose of the circuits in this thread. But it seems people have tested them with Yamahas and high end Roland modules, but not the TD6, which is the one I own.

[tazinnuedo]

the circuit only works with a piezo/switch input… if your input is physicaly “mono” in your module (input 4  so) there is no solution i think …   have you got the rim when you plug a real dual roland pad (main piezo and membrane switch like a cy5 for example)

[elrules]

Of course I can. The PD-8 and CY-8 pads are that, piezo + switch, and they work with 2 sounds in those inputs, head and rim.
But I have build all the 3 circuits and as I said here before they hasn’t worked.
Circuit 2 has near 0 sensitivity on rima and Circuit1/3 gives me the same sound (the one from the head).
 and i don’t know what to do.

[PFozz]

The “rim detection” part of your circuit 2 seems to work.
Try to connect the rim piezo “+” (ceramic part) to the tip of your stereo plug.
 
Best.

www.eareckon.com

[elrules]

ORIGINAL: PFozz

The “rim detection” part of your circuit 2 seems to work.
Try to connect the rim piezo “+” (ceramic part) to the tip of your stereo plug.

Best.

Do you mean I have to connect the two “+” of the piezos with a wire? or with a diode like circuit 1/3?

It seems you know how the circuit exactly works. I would appreciate if you could give a technical explanation about each part of the circuit, what do they do, etc. That information would be very very useful to me because then I could be able to change component values with the knowledge of what I’m changing, or to add or remove parts of the circuits to achieve what I need.

(Thanks for all of your replies)

[elrules]

Somebody there?

[Rogue]

Hi – Pfozz is currently on vacation, so you are unlikely to hear from him in the imminent future.

Best Regards,
RM

Rogue Marechal - Toontrack
Configuration Manager

[PFozz]

Thanx Rogue 😉

> Do you mean I have to connect the two “+” of the piezos with a wire? or with a diode like circuit 1/3?

You should try with a diode.

> It seems you know how the circuit exactly works.

Actually, Keith Raper is the man of the situation 🙂
I’m formerly not into analog electronics but here’s what I understand from the schematics :

.D1 and D2 won’t allow a piezo xducer to make his buddy “buzz”.
.Q1 acts as a triggered switch : basically, if there’s enough current coming to its “base”, Q1 allow what’s coming from its collector to flow to its emitter.
.R1 limits the sensitivity (more the value is, less sensible will be the detection)
.R2 increases the sensitivity (more the value is, more sensible will be the detection)

In the 2nd circuit, the “main” piezo xducer determines the velocity of a hit, while the “aux” piezo xducer is use to trigger a kind of switch that determines which zone of your dual pad is played.

In circuits 1/3, if you’re playing the first mono pad, its piezo transducer is used to determine the velocity and basta.
If you’re playing the second pad, its piezo is used to determine the velocity of the hits and what’s coming from this same piezo will make the circuit “link” the ring and sleeve parts of your socket.

Hope this helps,
Best.

www.eareckon.com

[elrules]

Thanks for your posts. I have now the ideas clearer.This thread and http://www.vdrums.com/forum/showthread.php?p=261412#post261412 has helped me a lot.

The only thing now is to receive my piezos and make my own pads and try to build this circuit to make them work

[KeiichiRX7]

Okay, i know this is really off the wall and odd for drumming, but would it be possible to get a variant of this that will convert 3 piezos into 3 switches?  I ask because a full set of e-drums with a module is a bti out of my reach, so ive taken to modding game controllers and building my own stuff.
 
currently (feel free to laugh) i’m tapping alng on a rock band drumset (yes the one for the video game), with a couple addon cymbal stands with pads mounted on top.  there are 3 extra buttons on the controller that i dont use for anything when it’s connected to my PC.  I’d like to take those buttons and put them to use by using a variant of the piezo-switch circuit.  Currently i’m planning on using a pintech pickup on each pad.
 
I know my controller is lowtech and doesnt offer much in the way of velocity control, but its what i can afford.  So in essence i’m playing sample pads not really electronic drums.
 
so yeah, the desired outcome is hit pad, close circuit

[bixpiu]

sorry for my difficulty to understand. with it is possible to connect two mono pads to a stereo exit and assign two sounds? i’ve a Yamaha dtxplorer and i would like to expand my set. i can use stereo exit for connect two pads?

[ricepattydaddy]

umm i have the alesis i/o and i would like to use chokable cymbals and 3 zone cymbals that i make myself. I dont understand what you used to make it work. i was wondering if you could tell me exactly what i would need just to make the Keith raper circuit. i have piezos, i have old crappy cymbals, i have soldering iron. plz explain in detail. exactly what i need to go buy to make this happen.

[Author]

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