Yes, they are +- 15Vdc. But why don't use a simple RC circuit instead of those BJT?You can use it for that too if the + and - signals are DC.
Thank you!!! You opened my eyes!Because by limiting the charging current to a constant value the output changes linearly with time, in other at a rate of some number of volts per second, a opposed to the logarithmic curve of an RC circuit. I think this is common in industrial controls.
This circuit is part of a voltage controller board. The rest of the circuit are juste simple gaind circuit.What's the rest of the circuit, what is it part of?