Hi,
as I'm just starting out in electronics and I had an old CPU power supply available, I thought to create everyone's favourite first project: an adjustable lab supply. As part of the lab supply, I want to build in a current limiter circuit. I came up with the below:
I've tested this on a breadboard and it seems to work - with the value of R1 as stated (2.2 ohm, actually 3*6.8 ohm 1/4W in parallel) the current is limited to around 550mA when I short circuit the load. Of course, the transistor and the resistors get hot (although the power through them is still within spec for both) when they need to pass this current.
I know the classic version of this circuit uses two diodes instead of the single LED, but when I use the LED I get a nice indicator of the circuit pulling too much current.
Now to my question - does anyone see any glaring mistakes or caveats in this circuit? Thanks!
as I'm just starting out in electronics and I had an old CPU power supply available, I thought to create everyone's favourite first project: an adjustable lab supply. As part of the lab supply, I want to build in a current limiter circuit. I came up with the below:
I've tested this on a breadboard and it seems to work - with the value of R1 as stated (2.2 ohm, actually 3*6.8 ohm 1/4W in parallel) the current is limited to around 550mA when I short circuit the load. Of course, the transistor and the resistors get hot (although the power through them is still within spec for both) when they need to pass this current.
I know the classic version of this circuit uses two diodes instead of the single LED, but when I use the LED I get a nice indicator of the circuit pulling too much current.
Now to my question - does anyone see any glaring mistakes or caveats in this circuit? Thanks!