Guest Posted February 10, 2007 Posted February 10, 2007 Not so much a gadget, but we haven't got an electronics forum out here. Just wondered if anyone had a cheap and easy way of making a DC-DC power supply to turn a 12VDC 2A power supply into a 5VDC power supply. I did think about just using a couple of resistors and capacitors paralleled up and making a +\-6Vish PSU, but maybe there's a better way?
luggsey Posted February 10, 2007 Posted February 10, 2007 Not so much a gadget, but we haven't got an electronics forum out here.Just wondered if anyone had a cheap and easy way of making a DC-DC power supply to turn a 12VDC 2A power supply into a 5VDC power supply. I did think about just using a couple of resistors and capacitors paralleled up and making a +\-6Vish PSU, but maybe there's a better way? Sure is, called a power transistor, used with a heatsink, three pins and dead easy. ----------------------------------------------------------------------------------------------------------------------------------- Life is like a box of chocolates, some bugger always gets the nice ones! My Amateur Radio Forum
Service Engineer Posted February 10, 2007 Posted February 10, 2007 Change the 12V regulator for a 5V one..? On quite a few PSU's the regulator outputs a voltage determined by it's input voltage which is controlled by a combination of resistor's or a zener diode, changing the values of these would alter the output voltage. ........................................................ Dave Partridge (Romec Service Engineer)
luggsey Posted February 10, 2007 Posted February 10, 2007 Change the 12V regulator for a 5V one..?On quite a few PSU's the regulator outputs a voltage determined by it's input voltage which is controlled by a combination of resistor's or a zener diode, changing the values of these would alter the output voltage. You could change the output power transistor if the input voltage was the same on both. ----------------------------------------------------------------------------------------------------------------------------------- Life is like a box of chocolates, some bugger always gets the nice ones! My Amateur Radio Forum
Guest Posted February 10, 2007 Posted February 10, 2007 Sealed SMPSU so it needs 'butchering'. What output current could I potentially have from it? I could do with as much of the 2A as possible as the one it's replacing is 2.5A, but I think that's overrated IIRC, it seems to be happily running with the current 'temporary' arrangement of using some of the insides of an old sat nav cradle with 5V output.
luggsey Posted February 10, 2007 Posted February 10, 2007 Sealed SMPSU so it needs 'butchering'.What output current could I potentially have from it? I could do with as much of the 2A as possible as the one it's replacing is 2.5A, but I think that's overrated IIRC, it seems to be happily running with the current 'temporary' arrangement of using some of the insides of an old sat nav cradle with 5V output. Depending on the input voltage to the convertor you may get more loss by reducing the output voltage, also lower voltage means more current.... ----------------------------------------------------------------------------------------------------------------------------------- Life is like a box of chocolates, some bugger always gets the nice ones! My Amateur Radio Forum
Guest Posted February 10, 2007 Posted February 10, 2007 also lower voltage means more current.... Yeah, I obviously already knew that. Butcher and tweak, then tweak it some more I think is what I think we'll be doing. I'll open it up and see what's inside it. It's a Vista 2A 'brick' type btw, just in case you were wondering.
luggsey Posted February 10, 2007 Posted February 10, 2007 Yeah, I obviously already knew that. Butcher and tweak, then tweak it some more I think is what I think we'll be doing. I'll open it up and see what's inside it. It's a Vista 2A 'brick' type btw, just in case you were wondering. It's possible it's just a switch mode without power transistor then? Another really easy way is to add a series of diodes, every diode will give a 0.6 volt drop, clumsey way of doing it but it will work if you have several 2A rated power diodes laying around! ----------------------------------------------------------------------------------------------------------------------------------- Life is like a box of chocolates, some bugger always gets the nice ones! My Amateur Radio Forum
Guest Posted February 10, 2007 Posted February 10, 2007 It's possible it's just a switch mode without power transistor then? It's likely that it is. Another really easy way is to add a series of diodes, every diode will give a 0.6 volt drop, clumsey way of doing it but it will work if you have several 2A rated power diodes laying around! I'm constantly amazed at what I have laying around!
luggsey Posted February 10, 2007 Posted February 10, 2007 It's likely that it is.I'm constantly amazed at what I have laying around! Easy source would be a couple of old voltage requlators from an old panel or the four fitted after the transformer on a old alarm (fire) PCB. ----------------------------------------------------------------------------------------------------------------------------------- Life is like a box of chocolates, some bugger always gets the nice ones! My Amateur Radio Forum
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