# Simple variable current source for approx. 2A, constant load

I need a variable current source as part of a power supply for an experiment I'm building. This part should heat up a filament, so the load is pretty constant. Timing is not a factor either. So what I'm looking for is a pretty simple solution, much simpler than a lot of circuits I find online. But all the simple circuits, like the ones attached are often calculated for small currents. I need a regulation between 1.5A and 2.5A and my question is if someone has experience with such simple circuits and higher currents. Of course I would use other parts like power transistor and other resistors but heat and efficiency could be problems, but I don't know to which degree. I study physics, so I'm no expert in electrical engineering.

I hope someone could give some intuitive answer. Thanks

• Is this meant to be a fixed 2A output, or do you need to be able to control it from 1.5 to 2.5 A? What maximum voltage must this supply be able to put out? What power voltage do you have available, or can you get whatever power supply is required? Commented Jun 6, 2017 at 13:13
• I need to be able to control it in this range. I could get whatever power supply is needed i guess. Was thinking to take a normal 12V or 24V power supply which can deliver 5A or so. It needs to be as small as possible. Commented Jun 6, 2017 at 13:15
• Sorry, english is not my first language. What more infos do you need? Commented Jun 6, 2017 at 13:17
• I'd go with something like B or the op-amp one which is more adjustable. Transistor needs to be beefy and have a heatsink. Sensing resistor needs to be small and rated for the power. Commented Jun 6, 2017 at 13:20