Yes, I agree with Denny. Try a switching supply for 110-220. They make DC out of the AC in and then convert it down. Try finding a 40-60 one that outputs 15 Volts (or 12 and trim it up)? The 110V mode usually goes down near 90-95 V? You can even take the metal cover off and bypass the full wave rectifier (to save voltage drop) or tweek the output voltage. Jameco has a lot to look it? Mike, WA6ISP ----- Original Message ----- From: "Denny Esterline" To: "Microcontroller discussion list - Public." Sent: Sunday, January 15, 2006 11:09 AM Subject: Re: [OT] DC-DC Voltage Converter - How to start >> Here asking for some help in the design of a DC to DC Converter. >> I have a solar panel with 96 to 100 VDC @ 1.1Ah without load, break >> point at 97 VDC and down to 60 VDC @ 0.9 Ah with load. >> >> The idea is to make a DC-DC converter from an input of 97 to 60 VDC to >> an output of 14 VDC more or less at 3Ah, this output will be used to >> charge a battery system. >> >> Can be possible to do this converter without any inductive device? > > Not effectively, but if the question is "is it possible to build a DC-DC > converter without inductors" the answer is yes. Switched capacitor > converters are commonly used for small boost converters (think MAX232). I > guess it would be _possible_ to reverse the general process, that is > charge > several capacitors in series and discharge them in parallel. But I've > never > seen a switched capacitor converter rated for more than a few milliamps. > So > yes, it's _possible_, but I can't recommend it. > > > Here's an off the wall idea- what about a regular switch mode wall wart / > power brick? The one running my LCD monitor as I type this is rated as 4 A > @ > 12V output, 90-240V AC input. Granted that's an AC input but the way these > things work is they rectify and filter the input voltage before it goes to > the switching stage. If you just tapped the output of your panel to the > internal HV DC rail... > 60V with full load is a little low, but it's worth a try > > -Denny > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist