Will a typical solid state wall mounted dimmer control the speed of a
small 120 volt universal motor (with brushes).
It was previously controlled with a low resistance wire wound variable
resistor which has failed, and If I can use one of the several dimmers I
have on hand that would be great.
On Fri, 23 Feb 2018 13:09:18 -0800 (PST), firstname.lastname@example.org wrote:
Speed regulation should be better with the dimmer under load than
the rheostat because it is not load dependent like a resistor. It
varies the power by time-slicing the torque instead of reducing it.
Normal dimmers are forward phase control.
A MLV dimmer (for magnetic transformer low foltage lighting) is
symetrical phase controland would likely be more suitable for the
inductive load of a universal motor. A reverse phase controlunit
(spec'd for electronic transformer low voltage lighting) might also be
better than a forward control as it switches on at the zero crossing
Lutron DVLV 10p is symetrical, 1000va, 600p is 600va - add csa suffix
DVRP 253P is reverse
The standard dv10p is forward 1000 va
(A PWM controller would be better yet, but is not part of this
Also another question. Are you SURE it was a rheostat, and not a
variac??? The variac would be MUCH more suitable than a rheostat for
the application and kinda looks like a rheostat.
I have a 210va Powerstat 10B in my hands as I type this - about 2.75
inches in diameter and 2 inches deep. A WHOLE lot more efficient than
A guy in Phoenix has one on Flea-bay for $76 USA (plus shipping - $96
to Canada - likely a LOT less within the CUSA.
I'll sell you mine for $75 Canadian Pesos but the shipping would
likely kill you. (The little blighters are not exactly light)
I recently tried using a dimmer to blow a 12 volt lightbulb with strange results. The reason I was doing so is I have a 7 watt cat flea killer which uses a 240V lightbulb to attract them, the trouble being the bulbs last about 2 weeks - they die as soon as I or a cat knocks them. So I tried a 7 watt heater, which didn't attract the fleas. I decided they needed the light aswell as the heat, so I thought about a lower voltage car bulb which is used to vibration and has a thicker filament. The trouble is 7 watts is hard to come by and I had to get a dual filament 7/27W bulb, and the only socket I could obtain only lit the 27W filament. I managed to short the two filaments together, but I needed to blow the 27W one. Attaching it straight to the 240V mains caused the bulb to explode, which was no good. The dimmer switch (turned gradually on) immediately blew a 1A mains plug fuse which I thought was odd, as the lamp didn't even light before the fuse blew. A 13A fuse survived and
killed the filament successfully, but I feared I'd break the dimmer by doing this many times. I'm going to use three car batteries to do so in the future (two seems to take forever - double the voltage just make the bulb very hot for 5 minutes before blowing, melting the plastic housing).
On Sun, 25 Feb 2018 22:13:38 -0000, "James Wilkinson Sword"
Don't they sell "hard service" bulbs there like mechanics used in
their drop lights? (before fluorescent and LEDs that don't burn the
hell out of you)
It is a bulb with a plastic coating on the glass and a special
filament that will put up with just about anything.
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