HomeRoast Digest


Topic: Dimmer purchased on Ebay (4 msgs / 91 lines)
1) From: Mark
All the discussion on triacs, etc. got me thinking about adding a dimmer to
my Poppery I, so I searched Ebay for one that would be suitable. I have just
purchased this one:http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item65519196&ed31941621&ssPageName­ME:B:EOA:US:2
(Grainger's website lists the same model for $70something, so $20 sounded
like a pretty good deal).
At 1500 watts, it appears it'll do the job. I'm not very knowledgeable when
it comes to electronics, but this seems a simple enough modification. I
currently have the Poppery's power switch controlling only the heater, with
the fan running continuously when the unit is plugged in. Will installing
the dimmer be as simple as cutting the wire to the heater and connecting the
dimmer in-line? Seems to me that's all there should be to it, but it's not
unlikely that I'm missing something, and I certainly don't want to damage my
roaster, or burn down my house. If any of the more electronically-inclined
in this group could confirm that it is indeed this simple, or point out what
I might be missing, I'd appreciate it. If it looks like a job beyond my
abilities, I'll enlist help. Either way, I should soon have a more
controllable roaster to play with. Thanks
Mark
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2) From: EskWIRED
At 1500 watts, it appears it'll do the job. I'm not very knowledgeable when
it comes to electronics, but this seems a simple enough modification. I
currently have the Poppery's power switch controlling only the heater, with
the fan running continuously when the unit is plugged in. Will installing
the dimmer be as simple as cutting the wire to the heater and connecting the
dimmer in-line?
----------
Yes.  Put it on the hot side.  It will come with a wiring diagram.
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3) From: Mark

4) From: dewardh
Mark:
<Snip>
much power I'm feeding to the heating element. I'm thinking I'll get an
inexpensive multimeter
Because of the way a "dimmer" (as opposed to a "variac") works not all 
"inexpensive multimeter[s]" will give a proper reading of actual power.  For 
half their adjustment rang the peak voltage of the dimmer's output stays the 
same . . . and, unfortunately for us, that's at the top of their power range, 
right where we're most likely to be running them.  Some (especially "digital") 
meters will read only that peak voltage . . . how, or how well, others 
compensate for the "chopped" sine wave is anybodies guess.  You'll probably get 
the most accurate (and meaningful) power reading with an old fashioned 
mechanical AC ampmeter reading 0 to 10 Amps.  Just remember that heater power 
varies as the square of the current drawn . . .
Deward
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