Convert 0-30V 3A PSU to 5A or more

[audioguru2]

Hi Sarma,
I have seen too many circuits posted that are built on a breadboard with thin long wires all over the place. Some are clipped together with intermittent alligator clips. They cannot work properly.

 

[mvs sarma]

Hi Audioguru

i agree with you completely-- power projects , for that purpose any project soud be built with proper discipline-- i was only teeling about lead loss compensation from the power supply to the load point--( say 50 to 100 cm for each lead). this itself drops the voltage and the resultant voltage at the actual load would be ( expected - lead drop). this could be compensated by a 4 wire system. that all.

regards

sarma

 

[audioguru2]

Hi Sarma,
I know about remote voltage sensing at the load so that the feedback causes a power supply to produce an accurate voltage at the load without the voltage drop of the connecting wires.

This project is smart because it has the current sensing resistor R7 outside the voltage sensing circuit. However, some people ruin the excellent voltage regulation of this and other power supply projects by connecting a current meter with its internal resistance in series with the load. I think that current should be measured by the voltage drop across R7 in this project, then there will not be a voltage drop.

 

[mvs sarma]

Hi Audioguru,

Current sensing outside cct Voltage sense-- yes. I shall come back  after a little study

Fine sir

regards

Sarma

 

[boco]

Hi guys. I am new on this forum. First of all I am sory for bad english but I hope you can understand mee. I read this posts about power suply modification to 5A. It is too much to read.I read 20 pages but after all I dont hav answer what should I change to get 5A. I know that you will said .....read. I am very busy (family, busines ....) and will be very greatfull if somebody write for me vhich part I must change.
Thank you for your answers.
Best regards
Boco

 

[audioguru2]

Hi Boco,
Welcome to our forum. ;D
We have another long thread about our 0V-30V/3A power supply project. It had problems so I suggested a few improvements to fix it. I have posed my suggested parts list many times in the other thread.

5A is not much more than 3A so the improved circuit is the same except a higher current power transformer is used, a 3rd 2N3055 output transistor with an emitter resistor is added to help share the extra heat and R7 is changed to 2.7 ohms/10W.

 

[bugmenot1]

Ops do you mean 0,27R 10W? Hehehe
Audioguru can I use 2 0,47R 10W in paralel for R7? Its the more aproximately value I found (for the 5A or more layout).

 

[audioguru2]

Ops do you mean 0,27R 10W? Hehehe
Audioguru can I use 2 0,47R 10W in paralel for R7? Its the more aproximately value I found (for the 5A or more layout).

Two 0.47 ohms resistors each will dissipate 2.9W (2.5A each) so a 5W size will be fine.
The voltage across them is only 1.175V at 2.5A each so the value of R18 will need to be increased or the max current will be much higher than 5A.

 

[ZeroKool]

I guess I came late to the show. I have finally read every comments for this 0-30V @0-5A modidification and is ready to build my own. Does anyone have a final revision of the schematic and PCB layout or know where I can find it? Please send it to me.

Thank so much
ZeroKool

 

[fuzhouled]

Good one learn a lesson