www.megadrum.info

Posted: **Tue May 10, 2011 10:23 am**

Hi

I would like to build Megadrum. As I understand it there are two possibilities, two boards (analog and digital) and a board all in one (2.5). Are both of these designs are the same technically? Are there any differences? It is better to build a version with two boards, or with one?

Regards.

Posted: **Tue May 10, 2011 10:36 am**

There are some differences and PCBs published in viewtopic.php?f=3&t=266 are what I recommend.

Posted: **Tue May 10, 2011 11:30 am**

So the board with 4051 and BAT85 is better than the 74HC4851?

Posted: **Tue May 10, 2011 11:36 am**

krzak wrote:So the board with 4051 and BAT85 is better than the 74HC4851?

74HC4851 = 4051 + BAT85 + Resistors

Posted: **Tue May 10, 2011 11:47 am**

codemaster wrote:
krzak wrote:So the board with 4051 and BAT85 is better than the 74HC4851?

74HC4851 = 4051 + BAT85 + Resistors

Yes, I know, but it seems to me that it's easier to make a board with 74HC4851

Posted: **Tue May 10, 2011 11:54 am**

krzak wrote:Yes, I know, but it seems to me that it's easier to make a board with 74HC4851

I think so too. But I could find on sale only 4051 in my shop

Posted: **Tue May 10, 2011 12:32 pm**

krzak wrote:
codemaster wrote:
krzak wrote:So the board with 4051 and BAT85 is better than the 74HC4851?

74HC4851 = 4051 + BAT85 + Resistors

Yes, I know, but it seems to me that it's easier to make a board with 74HC4851

If you use 4051 you can simply omit all BAT85 diodes from the PCB and replace input resistors with wires.

Posted: **Tue May 10, 2011 12:44 pm**

dmitri wrote:If you use 4081 you can simply omit all BAT85 diodes from the PCB and replace input resistors with wires.

Perhaps some hint how to do it, from what I know 4081 has 14 pins. Do I need to change something, or just put the chip into the socket?

Posted: **Tue May 10, 2011 12:46 pm**

dmitri wrote:There is only one reason for sticking with 4051s (and BATs) - DIP case versions of 74HC4851 ICs are not readily available in Europe and we have to pay a premium for delivery from USA to Europe, e.g. from Mouser it is around £15.

Posted: **Tue May 10, 2011 12:52 pm**

krzak wrote:
dmitri wrote:If you use 4081 you can simply omit all BAT85 diodes from the PCB and replace input resistors with wires.

Perhaps some hint how to do it, from what I know 4081 has 14 pins. Do I need to change something, or just put the chip into the socket?

You don't need to change anything besides "simply omit all BAT85 diodes from the PCB and replace input resistors with wires".

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