L200 Linear PSU with adjustable output Voltage and Current

Status
Not open for further replies.
I saw those modules before but I want to build one on my own, spending as little money as possible. That's why I started thinking to a L200 Ic.
 
GiacomoPascon said:
Now I'm undecided about what to build.
Maybe I should go back to a linear psu limiting the current at 5 amps...
Click to expand...

You're still talking lot's of heat and BIG heatsinks. The module I mentioned above, or the smaller 5A ones will be alot cheaper than anything you're likely to build, and far out perform it.

If you want to build a linear supply, and money isn't an issue, then you should use a tapped transformer and automatically switch different taps in as the voltage changes - this greatly reduces the waste heat - and is what commercial supplies usually do.
 
I want to try using what I have: 24v Trafo, 3 BD648, L200; to build a 30v 5A PSU.
I'm still searching a way to limit the current from 0 to 5A...
If anyone has any idea please tell me.
Thanks in advace.
 
GiacomoPascon said:
I want to try using what I have: 24v Trafo, 3 BD648, L200; to build a 30v 5A PSU.
I'm still searching a way to limit the current from 0 to 5A...
If anyone has any idea please tell me.
Thanks in advace.
Click to expand...
I used to use mosfet with sense current resistor. Op amp sense voltage on resistor and regulate gate of mosfet.

 
0,1R with 1A -> U = R*I -> 0,1V.
If you put 0,1V on pin 3 (+) of om amp, OpA will try to have same voltage on pin 2 (-).
Since you are sensing voltage on resistor, ground is yours reference.
Ploss on resistor is = R*I*I keep it in mind
 
MacIntoshCZ said:
0,1R with 1A -> U = R*I -> 0,1V.
If you put 0,1V on pin 3 (+) of om amp, OpA will try to have same voltage on pin 2 (-).
Since you are sensing voltage on resistor, ground is yours reference.
Ploss on resistor is = R*I*I keep it in mind
Click to expand...
Ok, thanks for the explanation, now I understand.
I have to buy an opamp to test this. I think LM324 will work well, right?
 
yes
In linear operation you should probably care about operating votlage range and input offsets
In this case 3mV. That means with 0,1R sense resistor you can adjust to 3mV drop -> I = U/R = 3mV/0,1R -> 0,3mA
frequency response parameter is for fast reading. -> switching topology


 
I searched for some good mosfets in my "collection" and I chose the IRFB20N50K. I also modified the schematic and added all the new components.
Thanks again for your help.
I'll try this as soon as possible.

PS. Here are attached the schematic and the mosfet datasheet.
 

Attachments

  • SchematicV4.pdf
    50.8 KB · Views: 327
  • irfb20n50k.pdf
    183 KB · Views: 296
Load needs to be before mosfet.
 
I'm back after trying the limitation circuit on bredboard.
I used an LM358D recovered from a board.
It worked until the MOSFET blew up.
The load was a resistor of about 2 ohm, and the circuit was delivering 2.5 amps to it.
Does anyone know why this happened?
Thanks in advance,
Giacomo.
 
I assume your mosfet does not like power losses.
(Vin-Vout)*Current or Vds*current
post values voltage current so on
 
Last edited:
Status
Not open for further replies.

Similar threads

M
  • Question
Low noise TEC driver design - adjustable linear voltage regulator
2
Replies
26
Views
7K
Tony Stewart
S
  • Question
Linear voltage regulator?
Replies
8
Views
3K
Papabravo
E
  • Question
2N2222A NPN transistor as Current Amplifier
Replies
9
Views
1K
Tony Stewart
  • Question
How to Create a 12V Breathing/Fading LED Circuit with My Current Components?
2
Replies
33
Views
3K
Lightium
N
  • Question
LM338 gives output voltage input
Replies
8
Views
4K
Tony Stewart
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…