DAREN of WV News February 26, 2017 (.C86)
WA8LLM (304) 679-3470 firstname.lastname@example.org
WOOD COUNTY EMERGENCY COMMUNICATIONS, 319 COMMUNICATIONS DR, WAVERLY, WV 26184
www.wc8ec.com or www.wc8ec.org
DAREN News, are articles and information about the Digital Amateur Radio "Emergency" Network of WV, which operates on 145.69 MHz. Anyone having any information about DAREN, or Amateur Radio in general, and would like to share it with others, may send it to WA8LLM @ PKBGWV on 145.69 MHz, or to my E-Mail: email@example.com. A State Wide DAREN NET is operated every Saturday from 7:00 pm to 10:00 pm, and lately, before and after those hours. The DAREN Net Announcement, showing the MAIN NCS, ALTERNATE NCS, NODEs accessible to both, and the previous week's check-ins, are posted by Thursday on most of the Main county DAREN PBBS'. The DAREN News can also be found on the www.wc8ec.com and www.wc8ec.org websites.
It's been a quiet week. I've been working with John Morris, WV8JM, about putting on a one day Technician Class license class. We have come up with a date of March 18th. The class will be held in Marietta, Ohio, at the Jesus Christ of Latter Day Saints church, 1503 Glendale Road. The class will start at 9:00 am with the administration of VE Testing at the end. If you know of anyone wanting to get their Technician License, have them contact me for further information.
Since information about the DAREN system is low, I'm going to write an article about a project that my nephew Sammy Mercer, N8SVX, and I have been working on. We've talked about writing the article, but hadn't started on it yet. Have you ever wanted to find a way to modify the power supplies that come out of the old desktop and tower computers, the ones that supply +5 volts at 20 amps, and +12 volts at 8 amps? We have seen and read several articles about modifying them, but they get too complicated. With this simple modification we were able to adjust the voltage to 13.8 Volts, but it may go higher. We didn't go any higher since there may be a high voltage protection circuit, besides, this article is about a 13.8 power supply. The modification that we do is very simple with the adding of one 10K ohm Trim pot, and a power resistor on the +5 Volt supply. From the tests that we made, we were able to adjust the Trim pot to output 13.8 Volts. The power supplies that we like the best are what we call the "small ones", they measure about 3 1/2 inches, by 5 1/2 inches, by 6 inches, and provide between 200 and 250 watts. The ones that we call big, are the ones that measure about 6 inches, by 6 inches, by 6 1/2 inches. We were able to modify them too, but the regulation wasn't as good. When we loaded the small ones down with high wattage resistors to 8 Amps, most of the voltages didn't drop below 13.3 Volts. The voltage on big ones loaded down to 8 Amps went to about 12.5 Volts. Most of the computer power supplies that we have been working with have one thing in common, they use one of two Switch Mode PWM (Pulse-Width-Modulation) Controllers. The two controllers are the TL494 and KA7500B. If you look at the specifications, you will find they are almost identical. If you want to modify one of the computer power supplies for 13.8 volts with this simple modification, you need to sacrifice the +5 volt regulation. In working with this project we ruined a few 8 Amp power supplies, by trying to load them down to see if they could supply 10 Amps. When the power supply says 8 Amps, it means 8 Amps. They provided 10 Amps for a short period of time, which means they should be able to provide a surge of 10 Amps. I'm not going to get into great detail about how the power supplies work, since it's all smoke and mirrors to me. I just researched enough to get an idea how they regulate the voltage. There are just a few simple steps. (to be continued next week)
There were only 33 check-ins to the State Wide DAREN Net this week. That's it for this week.