HV load idea -- I`m looking for some criticizm

[001]

I`m going to buid DC load for 0-400V 0-2А
The idea is to connect MOSFET and common light bulb(s) serial

The benefits of light bulb is low cost and compact size (instead of power resistors)
But I knew what impedance of light bulb is not constant

Is it problem?
Any opinions?

[Cliff Matthews]

That's 800 watts max.. no small project if you expect fine linearity. Tungsten filament bulbs are low resistance when cold, so at lower currents your MOSFET will have to dump most of the heat. Maybe 8 in parallel (each with 2 60-watt series connected bulbs, resistor divider and op amp feedback loop)? Just guessing..

*edit: Have you given thought to NiChrome heater element configurations? (such as those found in common hair dryers)

[daqq]

If you're going for cheap, as was suggested look into heater appliances, kettles, immersion water heaters, electric water heater elements, that sort of thing. They are generally pretty rugged. Also, they are by definition easy to get heat out of, especially things like electric water heater elements.

The benefits of light bulb is low cost and compact size (instead of power resistors)

Well, yeah, but you still have to deal with 800W of heat. Only a VERY small portion will end up being light, the rest is heat. The same goes for any kind of load. 800W is a LOT of heat to deal with.

[ahbushnell]

If you're going for cheap, as was suggested look into heater appliances, kettles, immersion water heaters, electric water heater elements, that sort of thing. They are generally pretty rugged. Also, they are by definition easy to get heat out of, especially things like electric water heater elements.

The benefits of light bulb is low cost and compact size (instead of power resistors)

Well, yeah, but you still have to deal with 800W of heat. Only a VERY small portion will end up being light, the rest is heat. The same goes for any kind of load. 800W is a LOT of heat to deal with.

The light ends up as heat also.