| Message | Date | From | Subject | ||||||||||||||||
| 12608 | 2016-04-06 10:01:32 | p1eiades | Bad news, good news, better news | ||||||||||||||||
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Bad news - my old HP printer died. Good news - a new Canon (with good resolution scanner) was on sale Better news - the HP left me with a 32v, 1.5a power supply. Wonder what I could do with that? ;-) ;-) For now, pack it away in prep for a move. Time to ponder options, eh? Joe | |||||||||||||||||||
| 12609 | 2016-04-06 14:11:33 | kerrypwr | Re: Bad news, good news, better news | ||||||||||||||||
I had a HP laptop supply, 17v & 3.3A, lying-around; I made a little variable supply for it;
http://s9.postimg.org/6oap0z4vz/image.jpg Just a basic LM338 regulator. The HP supply plugs-in and there is also provision for input from any suitable DC source. It has a little noise from the HP supply on its output but not much and it's fine for general work. I have several power supplies and didn't really need another but the old adage is that you can't have too many. :) Kerry VK2TIL. | |||||||||||||||||||
| 12636 | 2016-04-10 08:34:03 | Chris Trask | Re: Bad news, good news, better news | ||||||||||||||||
Nice adaptation of excess equipment.
>Chris Trask N7ZWY / WDX3HLB Senior Member IEEE http://www.home.earthlink.net/~christrask/ | |||||||||||||||||||
| 12743 | 2016-04-27 12:57:13 | Jack Boswell | Re: Bad news, good news, better news | ||||||||||||||||
Hi Kerry, I see that you have additional knobs and outputs on your bench power supply. What are they used for? do you have an addition regulator mounted inside? Thanks for the info. I have most of those components in the junk box and have a builders group that might be interested. 73's Jack 12746
| 2016-04-27 16:10:34
| kerrypwr
| Re: Bad news, good news, better news
| G'day Jack.
The red binding post is + output and the black one is - output. The other two binding posts are not connected to anything. I made a couple of "links" from PCB material; they can be seen here; http://s32.postimg.org/f2wt2idf9/Exterior_Final.jpg As shown above, the links provide two extra output terminals; one link can be fitted to allow series connection of an ammeter if accurate current measurement is required. There are probably other uses for a "floating" pair of terminals. The dual meter is a cheap ebay item; it's quite small. Voltage accuracy is OK, current accuracy less-so, probably because it's an expensive exercise to make a good temperature-stable current shunt. I calibrated it at one amp and it's OK for most purposes but the extra terminals provide an option if required. The circuit is just the app-note one for the LM338; the voltage-set pot is divided into two (5k & 1k I think) to give the fine & coarse settings. The switch controls the output and the LED indicates "output on". The case is a small diecast box; the four screws that retain the panel fit into the normal lid-retaining screw holes. The panel layout is done with MS publisher, laser-printed on paper, dry-laminated & trimmed and glued to the panel; it's a technique that I use for all my home-made things. DC input from the Dell supply is via a Dell-size input socket on the side; there are also binding posts to allow input from any DC source. I sometimes use another supply to feed this one, the advantage being that this little supply and its meters can sit right next to something that I'm adjusting, eg bias current, and I don't have to look up to read the meters of a PS on a shelf above the bench. That's about it; not much to it. Kerry VK2TIL. 12748
| 2016-04-28 09:16:32
| Jack Boswell
| Re: Bad news, good news, better news
| Hi Kerry Thank you for the explanation that is great. I am building it today. We have a local builders group that I am going to present on Tuesday night. Thank you for the Ideal's and great project. 73's Jack | |||||||||||
