[sdiy] best ways of portable +/- supply

Tom Wiltshire tom at electricdruid.net
Tue Jun 12 18:16:12 CEST 2012


You're looking for small, light, hand-held-size solutions, right?

I worked on an off-grid sound generation project recently, but it had car batteries feeding +/-12V DC-to-DC convertors. It worked well, but I don't think it's the sense of "portable" you're talking about.

Tom


On 12 Jun 2012, at 17:05, dan snazelle wrote:

> does anyone have opinions on the best way to get plus and minus rails into a portable synth/noisenaker/stompbox type project  WITHOUT using an on board transformer?
> 
> 
> the options I know of are
> 
> 1.AC to DC conversion (ac wallwart plugs in and is converted with regulators and caps to a DC dual supply.  Kind of bulky due to use of large caps.
> 
> 
> 2. Big DC wallwart....a 24 volts wallart would easily get plus and minus 10 volts once regulated. CHEAP and EASY. what are the downsides to this setup?
> 
> 3. DC2DC converters (put in 5 volts get out +/- 15 or +/- 12volts//////) convenient BUT very expensive, bulky, they get very warm and can be destroyed with overvoltage quite easily.
> 
> 4. CHARGE PUMP chips (max1044 etc)    cheap, easy...... VERY PRONE to destruction from over-voltage and static electricity. (though they are used in some pro boxes like the Moog Pedals so there must be ways
> to make them less error prone)
> 
> 
> 
> 
> 
> Often I am hit with a LIGHTBULB kind of a moment "oh this would be such a great project....so few parts and I could put it in a tiny box!" and then i realize that I will have to provide 2 batteries or a charge pump. Suddenly the small box is a bigger box and the 
> amount of parts has grown.
> 
> 
> 
> 
> 
> I have been messing around with the max1044/LT1045 charge pumps but overall I think they are a bit too delicate for road use....i have had a few MAX1044's die just from having a power supply 
> hooked up to them which briefly spiked at a higher voltage than 10 volts 
> 
> 
> (my Bench supply, when you turn it on, it seems to jump to a very high voltage for a split second....most chips seem fine with this but not the charge pumps (luckily I figured it  out quickly!)
> 
> 
> Maybe there are ways of protecting these power conversion chips I dont know about. (i usually just put a zener in front of them to keep the incoming power in the proper range) 
> 
> 
> ANY thoughts/advice appreciated
> 
> thanks
> 
> 
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