Wilson NPN Current Mirror

you experimenting, also irl?

Unfortunately I've run out of solder, but yes, I made a pretty basic one using 2N2222s and measured the current through the voltage drop using an oscilloscope connected to the collector of the NPN which is soldered on to the load or Iout.

ok, with 2n2222 but not with 300mA, right. Its importante to switch between both worlds. Simulation and real circuit. Get more soldering 👍😉

I think a 2n2222 can take up to 600mA

Yes, but look also at Vce and calculate the product of voltage and current. Max power dissipation of TO92 is 300mW. So 300mA * 4V = 1.2Watt which is four time to high and will burn the transistor. This max current is only possible if the voltage is low enough to not exceeds the maximum power ratings!

The wiki for the TO-92 package(https://en.m.wikipedia.org/wiki/TO-92) states that the package has a maximum 600mW dissipation. I don't know if this is correct but it is still below the 1.2 Watts and still 2 times over the maximum power ratings

correct, the absolut maximum for to92 is 600mW, but this is at ambient temperatur 25°C. So you wont be able to use it in automotive or at a hot summer day. Anyway, 1.2W was my calculation of how much power/heat you burn in this circuit here!!! Got it?

Yup, got it! Thanks for the help!

for example, the top right transistor here in your circuit http://everycircuit.com/circuit/4713416468725760 there are 300mA and from collector down to emitter we have 3.77V. this makes a power of 1.13Watt, and much more then your 0.6Watt at max25°C ambient temperatur. I prefer to stay away by a factor of 2 from this maximum, to have a little headroom in ambient temperatur. Anyway, there is beside this a much bigger issue, but its related to power and heat. Its called thermal runaway and matching. If you go more deeper into this type of circuit you have to understand it, cuz it will also be reason why nothing works as you see it here perfectly. But this you should do by learn at the basic current source first before you do any improvments like this wilson is. The basic two transistor current mirror does have some surprisses irl for you, check am out and build it

I'll take some time off some weekend to digest all of this info. Thanks for the clarification and the help!

great