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Help me design a PSU
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AngraMelo:

--- Quote from: BravoV on December 21, 2018, 09:13:26 am ---Alternative design , -> General Purpose Power Supply Design

Quoting the designer ...

"... I am only looking a very low cost high performance regulator that could be controlled by just plain potentiometers."


Read the 1st post carefully.


A sneak peek on the spec (highlighted few items that might interest you) :

3V to 30V input source voltage range
1.5V dropout voltage
True regulation down to zero volts
1A output current with 0 to 1A current limit
High level of protection from loads.
Transient performance similar to the LT3080
No-load to full load output voltage regulation  better then 0.001% (Wiring and track resistance is the biggest problem)
Loads like a battery can be connected to the supply while the supply is off without causing any problems to the supply or the battery.
Design based on "garden' components - potential to make it very cheap.
Possibility of a wide range 1A supply using only board mounted devices and no heatsink.

Oh yes, no negative rail needed.  :P

A sneak peek ...



Again, you need to read the whole thread, just a suggestion.

--- End quote ---

Bravo, what is use of the RC circuits shunting the OPamps output and input? (beginner here)
nemail2:
i have a 18V AC outputting transformator and i'm doing 4A current with a pair of TIP3055/BD139 Darlingtons from 0-12V without an issue. proper heatsink and fan req'd, of course.
at 1V output voltage and below it gets quite hot obviously but it has temperature monitoring and emergency shutoff just in case and besides, what hobbyist needs currents like this at such low voltages, anyway. 3.3V or even 2.5V at 4A it does without any issue.
Kleinstein:

--- Quote from: AngraMelo on December 21, 2018, 05:06:58 pm ---
--- Quote from: BravoV on December 21, 2018, 09:13:26 am ---Alternative design , -> General Purpose Power Supply Design

Quoting the designer ...

"... I am only looking a very low cost high performance regulator that could be controlled by just plain potentiometers."


Read the 1st post carefully.


A sneak peek on the spec (highlighted few items that might interest you) :

3V to 30V input source voltage range
1.5V dropout voltage
True regulation down to zero volts
1A output current with 0 to 1A current limit
High level of protection from loads.
Transient performance similar to the LT3080
No-load to full load output voltage regulation  better then 0.001% (Wiring and track resistance is the biggest problem)
Loads like a battery can be connected to the supply while the supply is off without causing any problems to the supply or the battery.
Design based on "garden' components - potential to make it very cheap.
Possibility of a wide range 1A supply using only board mounted devices and no heatsink.

Oh yes, no negative rail needed.  :P

A sneak peek ...



Again, you need to read the whole thread, just a suggestion.

--- End quote ---

Bravo, what is use of the RC circuits shunting the OPamps output and input? (beginner here)

--- End quote ---

The RC elements at the OPs are there to set the frequency response of the regulators. So they decide wether the supply works well, is too slow or oscillates because it tries to be too fast. Getting this part right is the real difficulty.

Trying to get 1 A with no heat sink would usually requite a switched mode supply, or a lot of transistors like 2N3055 that might work with no heat sink up to maybe 2 w. In a linear power supply there is quite some possible heat produced and not much to change with this.

It gets tricky to go down all the way to zero without a negative supply, as the typical BJT based constant current sink only works down to some 10-50 mV if one tries hard. So a negative auxiliary supply, even if only - 100 mV already helps a lot. This could be as little as 2 extra diodes with less voltage drop and a filter cap.
Efe_114:
I just recieved my order and i started experimenting with TIP142 and i found out voltage jumps up when i it hook up to a load. about 0.3 volts for a 1w power Led. and the worst thing is that overshoot doesnt recover! what could be the reason of it? Im using lm358 as a opamp TIP142 as series pass transistor a pot for referance a 100nF ceramic cap between opamp output and -input.
fsr:
I think that analyzing that will require a schematic. I don't get the part about the capacitor feedback. Only a capacitor would mean no DC feedback at all. And a pot for reference? Took from where? Please, show us a schematic.
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