I would like the option of running my synth from the internal battery or a wall wart. What would be the best way to wire this up?

Get a SPDT switch with three positions, On-OFF-On and a panel mount barrel jack. Wire the middle (pole) of the switch to the circuit and the outer two positions to either the barrel jack positive or battery positive. This should let you switch between the two sources with one switch.

send in a pic when you’re done :)

VOS Synth board v.1.02
My electronics skills are pretty basic but I figured this mod would be a no-brainer. Unfortunately I managed to cock it up. I am a proud man, so of course I’m only asking for help AFTER exhausting some admittedly questionable troubleshooting ideas and blowing my 556 in the process.
The chip has now been replaced and I am ready to give external power another try. Here is how I had the power switch and barrel jack wired up when things started to go bad:

-SPDT (On-Off-On as recommended)
-Top pole – battery positive
-Middle pole – power LED positive & JP1
-Bottom pole – barrel jack positive
-Battery and barrel jack negatives both going to ground
-Using a 9vDC, 350mA wall wart.

In this configuration the battery power worked properly, but the external power did nothing aside from eventually frying the 556 ;). Any hints?

Thanks,
Tim

P.S. I’ll send a pic when I figure out how to hide the embarrassing scorch marks around my shiny new 556

hm, first thing to do is check a 9V pad on the pcb when the wall power is selected and make sure it’s actually getting 9V (and not something like -9V!). The switch could be funky, or I may have advised wrong on the hook-up. It wouldn’t hurt to double check how it works by using the resistance checker on a volt meter. Make sure ground stays ground.

Sorry if I lead you astray on the switch hookup!

One other thing… when I’ve powered the beast with 9V from a power supply before, nothing worked at first. Turns out I was using really long wires from the power supply and it wasn’t able to supply power “fast” enough. ie, too much output impedance on the supply when compared to a battery. Adding a 100uF electrolytic cap across the 9V and ground on the pcb fixed this, but the VOS also lost a bit of its crazy character. Just another thing to watch out for.

I hooked the battery up wrong in my VoS sequencer and turned it on. Now the power light come on but it doesn’t sequence. What have I burned out?

i’m answering the battery hooked up backwards question in a new thread since it doesn’t continue on the same topic.