X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao106.cox.net ([68.230.241.40] verified) by logan.com (CommuniGate Pro SMTP 5.1.10) with ESMTP id 2145740 for flyrotary@lancaironline.net; Thu, 28 Jun 2007 11:27:23 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.40; envelope-from=dale.r@cox.net Received: from fed1rmimpo02.cox.net ([70.169.32.72]) by fed1rmmtao106.cox.net (InterMail vM.7.08.02.01 201-2186-121-102-20070209) with ESMTP id <20070628152644.GPPW3993.fed1rmmtao106.cox.net@fed1rmimpo02.cox.net> for ; Thu, 28 Jun 2007 11:26:44 -0400 Received: from [192.168.1.103] ([72.223.48.245]) by fed1rmimpo02.cox.net with bizsmtp id H3Sj1X00J5HQYSo0000000; Thu, 28 Jun 2007 11:26:43 -0400 Message-ID: <4683D32B.4070802@cox.net> Date: Thu, 28 Jun 2007 08:26:35 -0700 From: Dale Rogers Reply-To: dale.r@cox.net User-Agent: Thunderbird 2.0.0.4 (Windows/20070604) MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: BAttery Charger was: [FlyRotary] Amazing transformation References: In-Reply-To: Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Some of the products I used to service a lot utilized the DEC "Q-bus".
It's a 12-slot backplane (IIRC) with two power supplies - "left" and
"right". Since at least the first two slots are always occupied, the right
p/s always has enough load to function. However, since the backplane
had to be populated from right to left (no gaps), the left p/s often had
no load (to speak of - just backplane signals). Sooooooo, the last
slot in the backplane had a "load" pcb inserted - populated with an
array of ceramic resistors - to insure that the p/s would function
correctly.

I would think that a few resistors on a breadboard with appropriate
sockets for the unused connectors of a PC p/s would insure stable
operation. I have a few left-over power supplies from cases that I can
no longer get motherboards for (e.g. baby AT). I'll experiment a bit
and report back.

Dale R.
COZY MkIV #1254
http://members.cox.net/rogersda/Products.html

Ernest Christley wrote:

I believe this has to do with them being switching mode power-supplies. The way I understand it, the supply has a resonant circuit (something like 10kHz). That is passed through a transformer that is tapped in several places to give the various voltages. Without some load, the resonant circuit won't ring, and you get no power. To much draw and you kill the resonance again. I was using one to do anodizing on aluminum. There was a definite sweet spot that the supply liked to be in. Try to exceed two amps and the output would just drop off instead of increasing.

Monty, any idea how much current the derusting draws. I used one of the $3 Harbor Freight multi-meters in series with my anodizing supply. It'll handle 10Amps. If the current draw is low enough (which I suspect it would be if the process takes 24hours), you could use a wall-wart as a supply.