Important questions about MegaDrum Schematics

[mrx23]

Hello!

I have some questions about the Megadrum design.
If Atmega8 has 6 ADC channels what does the AnalogueConnector1.2 stand for?

Can I use 4N25 (not darlington) instead of 6N138?
Why is the ADC Aref=2.5V, when the input is ~0-5V from the piezos?
And it would be nice if the Aref pin would be buffered with 100n.
The internal Aref is 2.56V, if this voltage is necessary you can leave out the voltage divider.

Is there anyway to use MegaDrum Controller with Atmega8 version?
If not then the only possible setting is through an LCD + buttons?

What do you think about this interface with the piezos?
http://todbot.com/blog/2006/10/29/spooky-arduino-projects-4-and-musical-arduino/
It has an external protection (5.1V zener) instead of using the internal diodes.

Could you upload some kind of amateur video to youtube, like drumming with phone books (there is a similar concurrence video with eDrum)? Instead of drumming on pro equipment's.

This is a great project, and much simpler and cheaper than eDrum.
Thank you!

[dmitri]

Hello!

I have some questions about the Megadrum design.
If Atmega8 has 6 ADC channels what does the AnalogueConnector1.2 stand for?

It's a schematics naming convention - AnalogueConnector1.1 and AnalogueConnector1.2 are two parts of the same connector: AnalogueConnector1

Can I use 4N25 (not darlington) instead of 6N138?

It may or may not work. Mine didn't work.

Why is the ADC Aref=2.5V, when the input is ~0-5V from the piezos?

Aref is not fixed. It is variable between ~2.0v and 4.5V

And it would be nice if the Aref pin would be buffered with 100n.

Not in MegaDrum.

The internal Aref is 2.56V, if this voltage is necessary you can leave out the voltage divider.

From above answers you can see it is not the case with MegaDrum.

Is there anyway to use MegaDrum Controller with Atmega8 version?
If not then the only possible setting is through an LCD + buttons?

Correct. Unless someone writes a software to support it. Please note, I won't be adding new features to MegaDrum8 due to Atmega8 being low on memory.

What do you think about this interface with the piezos?
http://todbot.com/blog/2006/10/29/spooky-arduino-projects-4-and-musical-arduino/
It has an external protection (5.1V zener) instead of using the internal diodes.

Don't remember where I read it (possibly somewhere on Admir's http://www.edrum.info) but it won't protect inputs from overvoltages, possibly due to zener diodes being not very quick.

Could you upload some kind of amateur video to youtube, like drumming with phone books (there is a similar concurrence video with eDrum)? Instead of drumming on pro equipment's.

Anyone up for the task?:)

This is a great project, and much simpler and cheaper than eDrum.
Thank you!

Thanks for appreciation!

[Synthex]

Why is the ADC Aref=2.5V, when the input is ~0-5V from the piezos?
And it would be nice if the Aref pin would be buffered with 100n.
The internal Aref is 2.56V, if this voltage is necessary you can leave out the voltage divider.

The Aref is not fixed. It's for vary input gain.
Then, you can't add a 100nF buffer ...
http://www.megadrum.info/forums/viewtopic.php?f=3&t=134

What do you think about this interface with the piezos?
http://todbot.com/blog/2006/10/29/spooky-arduino-projects-4-and-musical-arduino/
It has an external protection (5.1V zener) instead of using the internal diodes.

Zener diode are not very good for that, and you still lose dynamic range ...

This is a great project, and much simpler and cheaper than eDrum.
Thank you!

Thanks !!

[mrx23]

Thank you for your answers!
I'll build it soon:)