Construction night a success

Back when I was ARROW president, I started a tradition of using one of our monthly meetings as a “construction night.” The first year we built a little keyer kit. In subsequent years, we built ladder-line J-poles, Arduino microcontrollers, and other little projects like that.

I’m happy to say that that tradition continues today. This month’s meeting, which took place on Wednesday evening, was the 2011 episode of construction night. This year, we built the Sure PS-LP11111 5~16 VDC Linear DC Voltage Power Supply Kit.

Sure PS-LP11111 5~16 VDC Linear DC Voltage Power Supply Kit

The Sure PS-LP11111 5~16 VDC Linear DC Voltage Power Supply Kit isn't a complete power supply, but the addition of a cheap AC wall wart makes it one.

This kit met all my criteria for a club construction project:

  • It was inexpensive. PartExpress sold me 15 of them for $9 each.
  • It was easy to build. As you can see from the photo above, the kit has less than 20 parts. It took me less than a half hour to build, and most of the club members had theirs put together in less than 45 minutes.
  • Those that built it have something useful that they can actually use in their shacks.  I plan to use mine to power the little QRP radio kits that I’ve built over the years. This thing should easily supply an amp at 9 V or 12 V.

As I said, this was a real success. So much so, that several of our club members said that we should do this more often. We even discussed other projects that might we might want to tackle.

One final note: Only one of our kit builders had any problem with his kit. Despite pointing out that the electrolytic capacitor, full-wave bridge, and the LED were polarized and had to be inserted properly, this fellow managed to insert his electrolytic capacitor in backwards. It worked for about two minutes before the capacitor exploded with a loud bang. We all got a big kick out of this because this fellow happened to be one of most experienced hams. :)

Comments

  1. Dave, N8SBE says:

    I found a 15 VAC 1.1 amp rated wall wart at the Kalamazoo hamfest last weekend, clipped off the too-small plug and mounted a 5.5mmm x 2.1mm plug and got the power supply up and running last night. A few observations:

    1) The 15 VAC wall wart showed 53V p-p (!) open circuit. I was concerned that this would be way too much for the rated input of the circuit (given as 16 VDC). When connected to the supply input, the DC coming out of the rectifier bridge was a more reasonable 22 or 23 volts.

    2) This, of course, is higher than the kit instructions say should be the max input, so I looked up the voltage regulators on the web:
    http://pdf1.alldatasheet.com/datasheet-pdf/view/22676/STMICROELECTRONICS/7805CV.html
    They are ST Microelectronics 7805CV’s. It turns out that the absolute max ratings for those particular parts are 35V, not the 16V listed in the kit instructions.

    3) Of course, running parts at max ratings is not recommended, so after some more digging in the datasheet, I came to the conclusion that running the input up to 25V was within normal limits, and you could get nominally up to 1 amp out of it (assuming that it is heat-sinked properly).

    4) It would be good idea to put some heat sink compound between the regulator case and the heatsinks. If you don’t have any handy, baby diaper rash medicine will do, since it contains zinc oxide. That’s a tip I picked up off of soldersmoke (http://www.soldersmoke.com)

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