Hi, you can set the current by changing the resistance of R3 - "trimmer" pot. The best way, (as Doug explained earlier) is to use 9V battery, and connect it like on the diagram:

- our CCS is Q1, Q2, R2, R4 and R3 pot
- connect +pole of 9V battery to the upper mosfet drain (where you`d connect B+=200V in "Guinevere")
- connect minus pole to the "anode out" of our CCS in series with 100 Ohms resistor - see the schematic
- connect the voltmeter (set on about 4V range or so) between the points B & C (across 100 Ohms resistor)
- you can set the P3 in the middle position, and slowly turn it on one side - the "goal" is 1,5V DC reading on our voltmeter. Ohms Law - 15mA "through" the 100 Ohms resistor is 1,5V DC voltage "drop". When you decrease the resistance - current increases, and opposite.
- in my case, I get R3=100,5 Ohms for the first CCS I built, and 112,6 Ohms for the second
- you can leave R5=100 Ohms in place when you install CCSs in "Guinevere" and check the current again
- for more, see "Grup Build" forum, I posted new PCB