Electronics > Projects, Designs, and Technical Stuff
Lab Power Supply - The Lost Current
<< < (21/26) > >>
C:
https://www.ti.com/ww/en/bobpease/assets/AN-31.pdf

https://en.wikipedia.org/wiki/Wheatstone_bridge

Would do your self some good if you studied these.
xavier60:
Some NE5532 op-amps I had bought on ebay arrived today. Although I have some TLC072 op-amps on order from Mouser, I  decided to try the newly arrived NE5532 ICs in my regulator circuit and noticed a drop in performance.
I'm not the first to have found this possible problem.
https://www.eevblog.com/forum/reviews/chinese-fake-op-amps/msg1443733/#msg1443733
radoczi94:
My overall experience with semicons from ebay are not so good. The ST branded semiconductors are generally cheap and low quality, but the chinese ebay thingies are worse than ST parts. I'd rather buy parts from a local distributor for 2x-3x price, than wasting my not-too-much time with some fake garbage. I guess you get what you pay for  :-\
xavier60:
My project has evolved into a useful bench supply.
The linear post regulator is supplied by an offline SMPS which does pre-regulation, maintaining 3V across the series pass MOSFET.
During early testing I found that the temperature of the MOSFET became much higher than  that of the heat sink at high load currents.
I soon figured out that the cause was the thermal resistance of the insulating washer used to mount the MOSFET to the heat sink, regardless of the type of material used.
The MOSFET's temperature is now much lower. I have mounted the MOSFET directly to a 6mm thick aluminum spreader plate which is insulated from the heat sink using silicone thermal sheet. The much larger surface area results in lower thermal resistance.   
Ill post an updated schematic of the linear regulator section.
 There is a messy aspect to my quick CC response idea. Ill try to explain this also. 
radoczi94:
Wow, that is a nice looking power supply! Good job, mate!  :-+

A lot happened around me, since I last posted here. Long story short, I did not had time and mood to work on this project of mine. I dig up some smaller projects and finished them, to have some fun. Learnt to use the new scope I bought on a basic level, helps a lot in troubleshooting. I did a lot of research too. I will design a range switcher circuit to switch between the secondary coils of the trasformer and a dual power supply for the control circuit. Then I will start experimenting with the schematic in the german ELV magazine, swapping out the opamps and try to use a more decent reference. It will be a long run, but I learnt again, that there are no shortcuts. Keep us updated about your PSU, I really like it!
Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod