Need to discipate 1A. - Materials Question

[CircularLogic]

This is pretty simple actually. I have a PLC that has a "light out" (LO) circuit that checks the filament of an incandescent bulb by intermittently pulsing the output. If there is no current draw, it sets a LO bit in the program.

I simulate the LO condition with an LED and a switch. I use a 15W 8ohm resistor to draw the required current.

My question is this...is there a discrete component that I can use to draw an amp (1A) that is smaller than a 15w resistor and/or produces less heat?

Any feedback is greatly appreciated.

 

[CircularLogic]

Sorry about not getting back sooner. Had to get on an airplane.

Actually, duplication of the physical behavior is absolutely necessary. Testing of the program in the PLC is only part of the process. Simulating real-life characteristics of the bulb outputs is also imperative. The voltage levels for the bulbs are not dictated by the PLC but rather a driver card that reports health information back to the PLC.

I think Biff44 might have something there worth investigating with the real question being how to effectively sink all that heat.


Here are some pictures of my existing rig. Keep in mind the front plate is screen printed aluminum with LEDs/switches followed by a layer of Plexiglas for insulation and then the resistor network on an aluminum plate. Push/pull fan setup to remove heat from bottom to top. Kinda crude, but works very well.



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James W. Hudgins, III
Union Switch & Signal

 

[itsmoked]

Yikes! A lot of time invested in that existing setup..

Why do you want to make it lighter?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[biff44]

It does not look that hard to design one. You would have the printed circuit board mounted on the same heatsink as the load chip resistors. So you would not need all those wires for interconnects. By using a fan, you should be able to keep the surface temperature down to a reasonable level.

Rich

http://www.MaguffinMicrowave.com

Microwave and wireless design consulting