I'm a diystompboxes regular who is trying to branch out. I searched the forum but couldn't seem to find the answer to what seems like a fairly obvious question. So, either it is so stupid no one bothered to ask it, or it has been answered and my searching skills suck.
Ok, so I wanna build an LM1875 based amp. Will a 18v wallwart power it? Is there a reason not to use wallwarts with chipamps?
The biggest reason I can think of is lack of amperage. Although, the voltage would be a problem two. 18v ww would only give +/-9volts, way too small.
Ok. I see your point. For the sake of my continued education, if I were to find a 40v wall wart (yeah, it's ridiculous), it would make +/-20v DC right? How would I wire it to the circuit? In my limited experience, a tranny has 3 wires while a wall wart just gives you + and - right? If we consider the schem -
(http://cordova.asap.um.maine.edu/~raymondj/imagehost/lm1875schem.jpg)
Where would Vee and Vcc come from if one was using a wall wart vs. a tranny?
I really appreciate your patience; I can't seem to get my head around this power supply stuff.
A wallwart with the desired spec is fine. As joe said, amperage is what you should also be looking at, and aslong as your in spec, you'll be okay. I particularly like laptop adapters to find a decent quality shortcut to building a PSU.
You would need to wire it into a powersupply section of a board that would go from positive 40v, negative is ground, to +/- 20 with a middle ground.
Ok. Thanks for the help, I understand it a little better now. I'll probly have more questions soon.
Thanks again.
QUOTE:
" For the sake of my continued education, if I were to find a 40v wall wart (yeah, it's ridiculous), it would make +/-20v DC right?"
I wouldn't say ridiculous. I have a 30v, 500ma one that I scrounged from a discarded inkjet.
Recently, on the DIY stompbox forum, there was a guy talking about modding a 30v (or possibly higher, I don't remember) power adapter. I don't know if he ever finished the project, but it sounded interesting to me, since my adapter just sits in a drawer. Maybe if you searched on that forum you could turn something up. Not long ago on ebay someone was auctioning about 10 adapters, and I remember some were fairly high voltage. So I'm sure they're out there. :D