How do constant current loads work and how to make one

[(*steve*)]

I think you should first look at this video so you understand the concepts and then we can talk specifics about the design you'll need.

 

[(*steve*)]

Your design will be different in some respects:

1. You'll need a far larger heatsink and probably multiple mosfets.
2. You won't need a 10 turn pot, a simple 1 turn pot will be fine.
3. The sense resistor will need to be smaller, perhaps 0R2
4. You may need a voltage reference.

What do you plan to power it from? 5V is pretty marginal (although it obviously can be done).

 

[Alexsieg]

Your design will be different in some respects:

1. You'll need a far larger heatsink and probably multiple mosfets.
2. You won't need a 10 turn pot, a simple 1 turn pot will be fine.
3. The sense resistor will need to be smaller, perhaps 0R2
4. You may need a voltage reference.

What do you plan to power it from? 5V is pretty marginal (although it obviously can be done).

Sorry I haven't been active lately, im busy with school. If it can be powered from 12v easily then I'll do that. If not then whatever isn't too high and can easily be done.

 

[(*steve*)]

12V will give you a lot more design freedom.

Your voltage reference could be something as simple as a 78L05

 

[AprilSteel]

voltage reference

I don't understand your use of this term here . Do you mean voltage out from a 12 Volt input? or maybe voltage in ?

Its all right I watched the video and I see it is voltage in.

 

[(*steve*)]

No, the voltage reference is a source of a stable voltage to which other voltages can be compared. In this case the voltage across a current sense resistor is monitored and kept constant to ensure the load has a voltage across it which allows a certain current to flow.

I'm not certain that the OP here knew what he wanted nor what a constant current source actually is. Normally, if you do, you have a much better idea of the current range and voltages.

 

[CDRIVE]

Depending on the value of constant current that you need, the LM317 is always a good choice (at least to me)

http://www.bristolwatch.com/ccs/LM317.htm

Miguel, considering what we all know about your limited access to components and hardware, this post really surprised me. My guess is that a Chinese cargo ship was passing the island, headed for the Port of Miami and this happened....

Chris

 

[hevans1944]

Miguel, considering what we all know about your limited access to components and hardware, this post really surprised me. ...

Huh? Aren't we friends again with Cuba? Surely Miguel can order and receive parts from DigiKey now!? And American's can now visit the island without fear of getting arrested upon re-entry to the United States.

 

[CDRIVE]

Huh? Aren't we friends again with Cuba? Surely Miguel can order and receive parts from DigiKey now!? And American's can now visit the island without fear of getting arrested upon re-entry to the United States.

Miguel: Depending on the value of constant current that you need, the LM317 is always a good choice (at least to me)

Perhaps this is now true but this sentence by Miguel seems to imply that he's had access to them for some time now.

Chris