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Laboratory voltage and current source |
After a long time, I decided to do some new design and because I did not have some regulated current source in my lab, I decided to do it. After a while on the Internet, I discovered a source that would match my requirements, so the current can be controlled from 2mA to 4A, which is sufficient for most applications, and the voltage can be controlled from zero to 30V. This power supply is very good up to 30V (or a little less, due to losses on rectifier diodes ..) when the voltage drop at 4A is maximum 1V. To this source I have heard more negative than positive, the reason why someone burns or oscillates is countless, but if the process is accurate and the component values are in tolerance, the source should not be a problem. However, I recommend to increase the values of the suppressor caps that prevent operational amplifiers from oscillating. If you do, the problem should not be. As the final power transistor, here is, according to the original scheme, used 2N3055, but it is possible and I recommend to use KD503,501 ... because maybe in the GM 2N3055 they are sold as National Semiconductor imitations that last 1/10 of the reported current. And then it can be used instead of 2N2219, which is before power, can be replaced by KF506. Otherwise, all components can be purchased normally and the price does not exceed 250Kč (without potentiometers and power transistor) power transistor can be easily found in old TVs (of course I mean KDčka ..) as well as filter capacitors. The source is initially built at 3A, but it also manages 4A when R7 is reduced. Then I also used two end transistors in parallel ... Schematic
Parts R1 = 2,2 KOhm 1W Manufacturing As I have a habit, the source I appropriately "miniature" and miniaturized as much as possible :-), instead of ceramic caps I gave better quality and more stable foil, precision IO sockets, high-quality wires and precision potentiometers, toroid.
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