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DIY Stompboxes => Building your own stompbox => Topic started by: madstringbean on January 11, 2010, 12:38:32 PM

Title: Two NPN boosts on one battery... problems... ack
Post by: madstringbean on January 11, 2010, 12:38:32 PM
Hey guys, I'm back and working on my ring modulator again.  This weekend I built two of those little boost circuits from the "beginner build" to use one of them for each of the inputs of my transformer/4-diode passive ring mod.  I want to power them both off the same battery and I was wondering if there was any specific way I need to connect things.  I tried it already and it didn't work but that might also be a problem with my layout (I made some changes to aron's layout to make it smaller).  Anyway, what I did when I tried to connect the battery was connect the grounds from of the two circuits with a little jump wire and then attach the battery's - lead to a random point on one of the ground sections... then I did kind of a Y connection from the power connect points on the two circuits where they each had a little jump wire coming from them and then met at a 3 way intersection with the battery's + lead.  Should this have worked?  I'm hoping the problem's just with the power setup and not with my two tiny, (identical) circuits... I should have tested the first one before I made another one that was exactly the same!

Title: Re: Two NPN boosts on one battery... problems... ack
Post by: GibsonGM on January 11, 2010, 03:40:12 PM
Yeah, make sure they both work independently!!
Then, you might wanna use a separate wire to each board/circuit from the  "-" terminal of the battery. This will avoid generating spurious noise currents in the ground lines....

I haven't had any trouble with "+" connections when powering multiple effects...I be sure to run an independent wire to each board from the power jack/battery clip.  Same as star grounding.  It wouldn't hurt to run a 100 ohm resistor in series at the jack or main board with a 1 or 10uF cap to ground for some filtering since you're running 2, but it draws so little you're probably ok without it.

Just don't run the ground from 1 board to the other board, then to the battery - might get noise troubles that way!

:o)