Electronics > Beginners
Help me design a PSU
VEGETA:
I think you need to see this: https://www.aliexpress.com/item/50PCS-TL431-TO92-TL431A-TO-92-431-new-voltage-regulator-IC-free-shipping/32694971062.html
I recommend getting it since you can use it in lots of other purposes and it is dirt cheap.
Here is ICL7660 if you wanted it too, which I recommend having for lots of different purposes:
https://www.aliexpress.com/item/5pcs-ICL7660SCPA-DIP8-ICL7660-DIP-ICL7660S-7660SCPA-new-and-original-free-shipping/32493575139.html
Both of them won't cost you 5$.
Efe_114:
I found out something funny was going on in the lm317 later it just shooted up to 12v and i wasnt able to change the output considering it is from the worst supplier locally i think it was broken
VEGETA:
--- Quote from: Efe_114 on November 28, 2018, 05:37:39 pm ---I found out something funny was going on in the lm317 later it just shooted up to 12v and i wasnt able to change the output considering it is from the worst supplier locally i think it was broken
--- End quote ---
I guess this is similar to what happened with me, sort of.
Probably this is due to limited total output power of the source, it could be say 10W total... So you could have 10V 1A, but when you draw 2A it will drop down to 5V regardless of how high you dial it. This is a well-known phenomena in all industry.
This occurs even on industrial supplies. One time we had a diesel generator which worked perfectly but then we connected a huge pump or motor which made the generator's voltage to drop down significantly.
Solution: use a better power sources, test it with DC-DC switching modules to verify its capability, then use it with lm317.
David Hess:
--- Quote from: not1xor1 on November 15, 2018, 07:43:46 am ---the original poster stated: no current limit needed
I anyway added a foldback current limit as I think it is the bare minimum for safe operation.
--- End quote ---
I took that to mean no adjustable current limit needed. I would still include short circuit protection.
I would use a single supply operational amplifier to drive an output transistor or likely Darlington with a Vbe current limiter on the output. This configuration is the same as that of a 723 but the NPN differential amplifier of the 723 cannot operate down to zero volts.
SiliconWizard's design is close to what I would do but I would add a reference and Vbe current limiter. (1)
Not1xor1's design requires a negative supply. If you are going to do that, then just use a 317 with the modification to operate down to zero volts.
(1) Who am I kidding? I would drive the output transistor using the positive supply lead of the operational amplifier and have the current limiting go into the *output* of the operational amplifier.
spec:
Of course, if you want the ultimate in simplicity for a 0V to nV output PSU, go for the LT3080 family of current reference regulators (take care with the layout and capacitors to ensure frequency stability though).
https://www.analog.com/media/en/technical-documentation/product-selector-card/LDO.pdf
https://www.analog.com/media/en/technical-documentation/application-notes/an142f.pdf
__________________________________________________________________________________________________________
https://www.analog.com/media/en/technical-documentation/data-sheets/3082f.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/3085fb.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/3080fc.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/3081fc.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/3083fa.pdf
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version