The battle plan is to mount some resistors on those heatsinks to warm up the disinsector.
These seem to be the right hammer for the job:
Aluminum housed resistors
The big one is rated 50 W @ 25 °C ambient. Use two, derated by 50%, times three air-cooled heatsinks for 150 W of low-temperature heating. The little one is 25 W @ 25 °C.
The derating curve is linear from 100% @ 25 °C down to 10% @ 250 °C, when mounted to a square foot of flat aluminum plate: -0.40% / °C.
Assuming a max heater ambient of 150 °F = 65 °C, you can use 84% of full power. Derating by 50% isn’t all that unreasonable.
The relevant hole locations:
- 50 W: X=1.562 inch / 39.67 mm Y=0.844 inch / 21.44 mm
- 25 W: X=0.719 inch / 18.26 mm Y=0.781 inch / 19.84 mm
- 10 W: X=0.562 inch / 14.27 mm Y=0.625 inch / 15.88 mm
Divide those by 2.0 for from-the-center offsets, which may be more useful for manual CNC operations: zero at the resistor mounting center, then back-and-forth from there.
The mounting hole size for 25 & 50 W resistors: 0.125 inch / 3.18 mm diameter, just exactly what you want for a 4-40 mounting screw. Tap drill #43, clearance drill #32 (close fit) or #30 (loose fit).
The mounting hole size for 10 W resistors: 0.094 inch / 2.39 mm to fit a 2-56 screw. Tap drill #50 (better: #49 for 50% threads), clearance drill #43 (close) or #41 (loose).
The Vishay-Dale data sheet is there
#1 by Erik Scott on 13-December-2010 - 11:23
There’s just something inherently cool about a resistor that needs cooling fins. I’ve used these for a satellite dish defroster. It’s pretty neat seeing wisps of vapor coming up from the dish when it starts to snow.
#2 by Ed on 13-December-2010 - 12:49
They look great, don’t they?
That gold anodizing is the finishing touch…
#3 by ozzy on 28-January-2011 - 15:44
cool idea do you know where i might buy these resisters thanx oz
#4 by Ed on 28-January-2011 - 16:29
The most recent batches came from Digikey and Mouser, but I’d expect any of the full-line distributors to carry at least one manufacturer’s version.
Read the datasheets carefully, as not all manufacturers use the same specs!