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*** Important Update:
While I was breadboarding this circuit i quickly realized that, while this circuit does work at least for lower supply voltages, the high dependency of relying only adjusting voltage levels with fixed resistances at the base actually causes a lot of problems that can cause things to over heat if you drive the bases too high when using higher supply voltages for example. So i plan to make a much more reliable version that is entirely current based control where it will no longer be influenced by the voltage supply your using, because all of the base currents will be regulated, and therefore independent of supply voltage, to an extent of course, (because too high, even at a fixed current, and the power will also increase enough to cause substantial damage). ***
BJT Transistor implementation of a VCCS that Can control extremely large currents!
1. Blue is current
2. Green is control voltage
Only limitations being the MOSFET and a Well-Suited power supply that can handle the high current… Just make sure the shunt resistance is proportionally decreased to handle the higher current or increased to be sensitive enough for a lower current range.
The shunt resistor can literally go as low as you need or want it to, but the lower it is, the more precision you’ll need to have over your control voltage. Recommended you implement the control voltage source with an NPN voltage follower (base resistor can be 100 ohm, with a 2k potentiometer if you’d like) in real life.
The more turns or steps your potentiometer has, the more fine tune your control will be of course. If you don’t have much, and you want even better fine tune adjustment, you can just add a resistor in series to the POT, the greater the additional resistor is in value, the lower the voltage range will be, (depending on how large the ratio between the two is). So make sure you know where you want the current (cause you’ll have much more control, but only over a smaller range of values) it’ll take a little trial and error to get the range and precision where you want it if you decide ti do so, but it should still be relatively easy, and offer much better control. For example, you should be able to turn it farther and it not make that big of a difference in load current, so you can more easily fine tune the current to exactly where you want it without being so sensitive that you can’t change the current in small enough steps
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