Method for powering nichrome heating element
Method for powering nichrome heating element
(OP)
I have a project where we need to heat a small part up for a few seconds in the range of 100-120C. The best approach looks to be a small coil made of a few turns of 18 gauge nichrome wire. Open loop control will probably suffice for this application. Guessing that power needed will be in the 10's of watts. Once I determine the power required it should not require adjustment.
What are the typical methods of powering low power resistive heating elements?
I am thinking of using either:
1. A toroidial step down transformer with just a low value series resistor.
2. Phase chopping SCR circuit on the primary of the step down transformer.
Any guidance or tips from experience would be appreciated.
A 20kW desktop furnace this is not!
-AK2DM
What are the typical methods of powering low power resistive heating elements?
I am thinking of using either:
1. A toroidial step down transformer with just a low value series resistor.
2. Phase chopping SCR circuit on the primary of the step down transformer.
Any guidance or tips from experience would be appreciated.
A 20kW desktop furnace this is not!
-AK2DM
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"It's the questions that drive us"
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RE: Method for powering nichrome heating element
Dan - Owner

http://www.Hi-TecDesigns.com
RE: Method for powering nichrome heating element
An $8 light dimmer might work, but it might not be suitable in some circumstances.
Once you determine the required power, then perhaps a fixed value heater could replace the adjustable version.
RE: Method for powering nichrome heating element
RE: Method for powering nichrome heating element
Hooked it up to a variac and hit target temperature in a few seconds. Variac was set to 40VAC. I opended the case and found the primary 120VAC and secondary 6VAC coil sets in parallel. 30VA unit so 6VAC out at 5A max. The is also a 220mohm resistor between the xformer and heater. I'll start out with a 2-3VAC xformer, but will take a voltage and current reading of the current setup as a starting point.
Had problems trying to find an off the shelf heater coil. 3-4mm ID, 1cm long, 2-3 turns. Coil is nice because it is noncontact (optical scrath/dig requirement) and allows us to see the process within the part during heating.
Thanks for the tip on the variac, luckily we had one floating around.
Thansk again and have a good weekend.
-AK2DM
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"It's the questions that drive us"
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RE: Method for powering nichrome heating element
RE: Method for powering nichrome heating element
Something like:
http:
Or perhaps:
h
And pick up one of these thermocouples:
http://www.omega.com/ppt/pptsc.asp?ref=IRCO-BW
Then just drive what you have now.
Keith Cress
kcress - http://www.flaminsystems.com