I use a variac with an AC ammeter in line. I like to heat test kit using a hot air gun on low setting. But for the low heat range, a diode is in series with the mains, the one-sided "switching" 50/60 times a second causes horrendous magnetising current problems that would overheat the variac I'm sure, used on the same mains ring main. Replace that diode with a preset triac for balanced "switching" ? I one time niaively thought putting a 1N4007 in series with a 50W, 24V soldering iron Tx would give a low temperature iron for melting plastic, ended up melting the 24V Tx. What effect , if any , would such diodes in say hot air guns, falsely? register on a moving disc mains kWh meter or the recent "smart" meters / monitors ?
Diode in series with the mains
Feb 16, 2015
4 Replies
** On the output side?
** You are exaggerating a bit. **Could be a gotcha there - how does the fan get its power?
In my old Black & Decker (Made in England) 1600 watt gun, the DC fan runs via one diode from a tap on the main heater winding. The half power diode has the same wiring polarity so fan operation is not stopped at half setting.
Fit a triac and the fan would lose half its power, so the air would be just as hot with either setting.
** Suspect half wave loads make them under read a bit.Why not try it out while counting turns on the big wheel
.... Phil
Diodes I ever seen are always on the secondary side of the transformer.
** Everyone is MISSING the point here.
The *diode* in question is INSIDE the hot air gun !!
Using it produces an ASSYMETRICAL load on the AC supply.
That in turn produces a small DC OFFSET in the supply - maybe 0.5 to 1 volt.
THAT in turn causes partial core saturation, particularly with TORROIDAL transformers, on the same supply circuit.
When did a toroidal come into the picture ?
WTF do you think a Variac is??
FYI"
The Nutcase Kook Troll **NEVER** explains anything he posts.
.... Phil
Not directly relevant to this discussion, but I am reminded of this story. Perhaps you'll like it:
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