I made a school boy error in buying the BS170. It doesn't produce enough continuous current to power my leds. They're bicolour and can only be wired in parallel hence I would need at least 2 amps!
Since I can't return them I was wondering can I just get some transistors to amplify the current up to 2.5 amps. Also would it have a knock on effect on the resistors am using?
I have 20 copies of this circuit on strip board. Some of the leds are grouped together and switched by one mosfet hence the 2amp
Sorry the led is actually supplied by 5v regulator which isn't on the diagram
Best Answer
You don't need to "amplify the current". It will flow automagically when you switch the LEDs on. The thing is that you need a switch (MOSFET or BJT) which can stand the 2A.
A power MOSFET would be ideal, since they're available with very low \$R_{DS}(on)\$, so they won't get very hot. You can do a parametric search on this Fairchild page. For example the FDN339AN and FDN359BN have low \$R_{DS}(on)\$.
An other option is to use a darlington transistor. They're not ideal though: \$V_{CEsat}\$ is rather high, often 2V, so when you run 2A through them you need some cooling.