0-30V Stabilized Power Supply

[Biggy Boy]

Had a look for  MC34071 and TLE2141 op-amps at the supplier and on EBay but could not find them!
Did find and bought 3 OPA445 op-amps on EBay.




Glen

 

[audioguru2]

You are in Ontario, Canada so you can order the proper opamps online from Digikey or Newark.
If you order before 8:00PM then they are delivered the next morning.

The latest version is designed for the MC34071 or TLE2141 opamps that have inputs that work at 0V and have outputs that go close to ground. They have a 44V supply rating.

OPA445 opamps have a high voltage rating but the inputs do not work near ground and the output does not go near ground so they need the earlier version of this project.

Maybe the OPA445 opamps you bought are counterfeits.

 

[Biggy Boy]

Ya I get my SMT parts from Newark and Mouser, they would have them too.
I''d have to wait for a while until i need lots of parts before placing an order, they charge $15-20 for shipping.
Not sure what Digikey charges for shipping.

I am using the APO445 op-amps for the old project.

If and when I make the new project I'll use the MC34071 or TLE2141
But for now I'm playing with the old board, to make it work better.

If I'm not happy with the results,
then I'll make a new board using the correct new schematic and parts list.
But for now I'm playing with the the old version and experimenting.  


Glen  

 

[singonn2]

guru isn't i can connect the fan cooler to the line about 3xV after bridge rectifier and add a resistor for reduce the voltage to the fan.

half-wave rectification ripple is too high, i hope the fan wont easy mangle, for economize diode and circuit can just borrow the current from bridge rectifier? isn't in theory full-wave rectification ripple algorithm same with bridge rectification ?

 

[audioguru2]

guru isn't i can connect the fan cooler to the line about 3xV after bridge rectifier and add a resistor for reduce the voltage to the fan.

half-wave rectification ripple is too high, i hope the fan wont easy mangle, for economize diode and circuit can just borrow the current from bridge rectifier? isn't in theory full-wave rectification ripple algorithm same with bridge rectification ?

You never told us how much current the fan needs. A resistor in series to limit the current might prevent it from starting to run since it needs much more current to start running. The resistor might get very hot unless it is huge.

 

[effenberg0x0]

Some posts in some threads are missing, including this one. I believe two/three pages of posts here. Mixos said it was a hack attempt. At least we didn't lose everything this time.

 

[effenberg0x0]

Agreed. Had to opportunity to see the defacement part of it.

 

[Holt]

Does anyone have a single side pcb layout they wish to share on this site?

Holt

 

[lysium]

hi all,

is it possible to use LT1491 for the op-amp? coz i have few on my drawer

thanks,

 

[audioguru2]

is it possible to use LT1491 for the op-amp? coz i have few on my drawer

They use extremely low power which shows because they are much too slow. Their output drops above only 800Hz. They are also very noisy.

 

[kvakva]

I was observing schematic of this power supply unit, and I would like to know how does it actually works? I can lightly understand how does it works, but can not apprehend details. There is a general description of this P.S.U. but, simply I would like to know more details. Is there any DETAILED description of this P.S.U.? I am especially interested about U1 voltage reference. I don`t understand how output of U1 gradually increases? What makes potential difference on the U1 plus and minus terminals to force output rise?
Any additional explanation about this P.S.U. is welcome (some site, text, reply, picture, pdf document...).
Best regards,
ing. Sarkezi Michal.
[email protected]

P.S. sorry for my bad english.

 

[audioguru2]

Is there any DETAILED description of this P.S.U.? I am especially interested about U1 voltage reference. I don`t understand how output of U1 gradually increases? What makes potential difference on the U1 plus and minus terminals to force output rise?

When power is applied, D8 does not have enough voltage to conduct but the opamp has positive feedback from R5 nand R6 so it greatly amplifies the noise in the opamp until the output voltage reaches about 10V when the zener diode D8 begins to conduct.
When pin 2 rises to +5.6V then the output is 11.2V.

 

[dracu_n_dulap]

so.... i'm back again to be annoying ;D
to turn my psu into the 5A variant the transformer has to be 2x30V at how much amperes.

 

[audioguru2]

so.... i'm back again to be annoying ;D
to turn my psu into the 5A variant the transformer has to be 2x30V at how much amperes.

I don't know why you have two 30V windings on your transformer.
30V makes a peak voltage of 42.4V that feeds the bridge rectifier and main filter capacitor. If the load on the project is 5A then its max power is 42.4V x 5A= 212W.

Therefore the 30V transformer must be rated at 212VA or 7.07A or it will get too hot.

 

[GrahamG]

So I decided to throw D15 away and replaced it with a peace of wire. Now I am able to get 30V with 3A.
If someone has the same problem as I (The rectifier voltage is to high for the oamps with 44V) you can use D15 which should have only as much voltage as you need to get under the 44V. The voltage in my circuit is about 39.6V - 44V and nothing is damaged.

I have just started with this project and am reading up on all the alternations/changes that have been made but I can't find "D15". Am I missing something in the schematics ?

 

[dracu_n_dulap]

I don't know why you have two 30V windings on your transformer.
30V makes a peak voltage of 42.4V that feeds the bridge rectifier and main filter capacitor. If the load on the project is 5A then its max power is 42.4V x 5A= 212W.

Therefore the 30V transformer must be rated at 212VA or 7.07A or it will get too hot.

7 A..............i understand a bit expensive to order but ok
i made a mistake writing the 2x30 i was thinking about something else and it doesn't have anything to do with electronics ;D
was a way for me to say that i have 2 psu
tanks!
good luck!

 

[audioguru2]

I have just started with this project and am reading up on all the alternations/changes that have been made but I can't find "D15". Am I missing something in the schematics?

I don't know whose schematic has D15. Mine shows a new 10V/1W zener diode that reduces the supply voltage to U3 but it does not have a part number and is missing on my latest parts list.

 

[GrahamG]

audioguru - thanks for the reply. must be a mistake in the forum as i read every page on the lab psu and one article mentioned D15. Perhaps a different project.

 

[lysium]

They use extremely low power which shows because they are much too slow. Their output drops above only 800Hz. They are also very noisy.

Thanks audioguru for the answer

 

[seba_031]

So is it good to make the power supply by the original scheme and parts or not?