I googled for a constant current source and came along the lm317.
I both simulated it (in multisim) and built up the simple circuit, but I neither get a constant current when i attach a load!
I googled for a constant current source and came along the lm317.
I both simulated it (in multisim) and built up the simple circuit, but I neither get a constant current when i attach a load!
I suspect that the problem is that the drop-out voltage is too high for his application.
The LM317 has a drop-out voltage from anywhere between 1.5V to 2.5V depending on the current and temperature, then you have to add on 1.25V for the voltage referance which gives 2.75V to 3.75V. This means that if he's doing something like powering a blue LED from a 6V supply then it won't work.
hi guys,
in fact i should have thought twice before actually posting...
first of all: i didnt create the circuit i linked to - i just linked to the resource i used.
second: you are right: i tried to build a perpetuum mobile that is, the consuming power was higher than it actually could be (load was much too high in order to drive my desired current through the it)