Electronics > Projects, Designs, and Technical Stuff
Dual channel 0-15V 0-500mA power supply
kallek:
Update to this project. Two days ago I got four of these nice Kyoritsu panel meters. ^-^ Yesterday we bought 1mm and 1,5mm thick sheet metal for metal project box from local metal store. Today I started cutting and drilling. 8)
kallek:
Here is the schematic. I might have made mistakes, so please give your suggestions. :)
EDIT: R3 should be 4.7k, not 470.
xavier60:
Make provision for compensation components for the CC op-amp.
A series resistor feeding pin 6, also a speed up diode across this resistor.
A series resistor and capacitor from pin 7 to pin 6.
The high value of R7 will cause some extra CC op-amp input offset.
It might be better with D8 across the B-E junction.
xavier60:
Actually I bread-boarded the CC loop and found that compensation isn't really needed. There is a short burst of ringing when the load is applied due to lead inductance. I don't expect this to be a practical problem. I would still put a resistor in series with pin 6 just for input protection.
kallek:
Thank you xavier60, some good points!
I am not very experienced in electronics yet, and not very good at english, so there are couple of things i have to clear.
I somehow understand the purpose of resistor feeding pin 6, but what that diode across it do? How I should bias it?
I put D8 there to prevent Q1 turning on if pin 7 can not go complitely down. But is it something to do with switching speed? Did you mean reverse biased diode across B-E junction?
Because I made the board before understanding to ask help, I will now experience with it and modify it if necessery. I will use your tips to do things better in the future. I really appreciate you sharing your knowledge!
Edit. Thank you xavier60 for your time! So you only recommend resistor or resistor and diode both?
Kalle
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