[NSRCA-discussion] Foam cutter power supply

[J N Hiller]

I remember reading about using two dimmers. I believe the reason for using
two is to get a more sensitive adjustment near the voltage (15) we need. I
have used a single dimmer for mane years, which worked sort of. It wouldn't
turn on below about 25 v but could be adjusted down to 15 without shutting
off. The cure was to load the dimmer with a light bulb connected in series
with the wire and dimmer. A 300 w bulb greatly reduced the sensitivity of
the dimmer. The voltage across the light bulb is around 75 loading the
dimmer to about 3/4 full on for very broad adjustment, 150 probably would
have been enough.
There is a shock (electrocution) hazard using household current. Although I
haven't tested it I have a GFI outlet in my shop that I use. The transformer
based power supplies isolate and separate the household (primary) from the
secondary output voltage eliminating possible contact with household
current. If I didn't already have a usable power source I would just buy one
(plug & play).
Jim Hiller



-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Paul LaChance
Sent: Thursday, May 21, 2009 1:26 AM
To: NSRCA Mailing List
Subject: [NSRCA-discussion] Foam cutter power supply

Hi all,

I was told about a way to make a power supply for a foam cutter using 2
dimmer switches.  I was also told to measure the final voltage to get an
approximate starting point of 15 volts.  I am not getting a voltage change
with the dimmers.  I have tested to see that there is a difference by using
a drill to see that it is reducing the speed.  Does anyone know how I can
measure to get a starting point or is it going to be trial and error?

Thanks in advance,

Paul
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