DAREN of WV News March 5,2017 (.C87)
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.
Well, it looks like I lost another DAREN station. While trying to post the News and Net Announcement last week, I wasn't able to connect to the Jackson County NODE/PBBS of JACKWV/RPLYWV. It looks like I have a lot of work to do with Jackson, Wirt, Roane, Wetzel Counties down, and Ritchie County working as a Digipeater only.
(continued from last week)
To understand what happens when modifying the computer power supplies from 12 Volts to 13.8 Volts, here is a brief explanation. Since we don't know for sure, but from what we can tell, is the Switch Mode PWM (Pulse-Width- Modulation) Controller TL494 or KA7500B has several functions, but the one we are interested in is the Error Amplifier/Comparator on Pins 1 and 2. When the load on the +5 Volt supply drops the voltage, a sample of the voltage is sent to Pin 1. The Error Amplifier/Comparator compares the sample voltage to the reference on Pin 2. If Pin 1 is lower then Pin 2, the Comparator tells the rest of power supply to change the pulse width, and crank up the voltage, and brings the +5 Volts back to where it should be. Since the +5 Volts is the primary voltage of the power supply, it tends to make the +12 Volt go up and down. So to keep the +12 Volts more stable we send a sample of the +12 Volts, instead of +5 Volts, to Pin 1. Now when the +12 Volts goes down because of its load, the Comparator tells the +5 Volts to go up, which brings the +12 Volts up. We get a sample of the +12 Volt from the newly installed 10K Ohm Trimpot. By having an adjustable sample of voltage for Pin 1, we can adjust the Trimpot to +13.8 Volts. When the load brings the +13.8 Volt down, the Comparator brings it back up. Now that we have an idea how to modify the power supply to put out +13.8 Volts, we need to do the modification. The modification will be accomplished in steps.
(to be continued next week)
There were 35 check-ins to the State Wide DAREN Net this week. There was one participate to the net this week, that I would like to welcome back, and that was Steven Houchins, KB8KKV. Steven has been missing from the net since February 26, 2005.