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Mini-Tubes 2 PCB

5/10/2000 3:11 PM
Ally Mini-Tubes 2 PCB
Hey Guys!!  
Has anyone come across a Minitubes 2 PCB layout?? Or has anyone made one and still got a .GIF of it?  
If not has anyone got or know of a program that will auto layout the tracks for me. For free preferablly!!  
5/10/2000 4:37 PM
There is a FREE (as Jack likes to say) layout at GEO, - just follow the links.
5/10/2000 9:35 PM

Went to the GEO site but the layout has the components over it.  
Do you have a link to the foil side layout posted at your site.  
5/10/2000 10:23 PM
Not there? Hmmm...  
I'll fix that up tonight when I get home.
5/14/2000 9:31 PM

Hay guys,  
I just finished my Mini-Tubes I and it sounds great.  
I did the PCB myself and got it pretty small. I was interested in your layout for the II since that is my next project. I also did a layout for that one but of cource without the converter or the switching transistors.  
What I wanted to know is if the converter and switching transistors will drain the batt. much faster. Also, my first version has almost too much gain, even on 9V. Is the +30V from a converter necessary or even desireable?  
Anyhow, I am interested in your test results and the full scale trace pattern.  
Thanks, Barry
5/14/2000 11:04 PM

"if the converter and switching transistors will drain the batt. much faster."
We engineers have a saying that "Mother Nature waits for you at the end of the assembly line", indicating that however wishful you are, natural laws will prevail when you try to get it to work.  
Yes, running something - pretty much anything! - on a higher voltage will eat more energy per unit time than at a lower voltage. I would guess that for this circuit, the power used will be about linear with the voltage, so the batteries should last 1/4 as long if they're converted to four times the voltage, all other things being equal. That may not be a bad thing, as the drain is pretty low at 9V, so you may still get a long time with a quadrupler.  
"my first version has almost too much gain, even on 9V. Is the +30V from a converter necessary or even desireable?"
Gain is NOT linear with voltage; in fact, it is sometimes true that clipping gets softer at higher voltages on an amplifier. About all that you can say is that other people have liked the sound with higher voltages. You ought to pick the one you like best. If that's 9v, great! You don't have to go to the expense and effort of making a converter.  
The checking looks good. I've re-drawn the wiring diagram to be more complete, and changed the second converter chip to be a 7662, as the LT1044A can't work well at the higher voltages as the second converter chip.  
I'll be posting the directly printable toner pattern. I have also come up with several alternate ways to do the up-verter if you like that.  
You can run the thing from a 6Vac, 9Vac, or 12Vac wall wart with a diode/capacitor multiplier, or use a 555 timer chip to convert 9Vdc to +32V. I'll be posting those converter sections.
5/15/2000 1:42 PM

Thanks for the explaination on using the higher voltage. I should have thought that through a little more and realized that gain is not directly related to voltage. Looking forward to those patterns.  
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