hyland psu high power mod

[p.larner]

can ths be modded for higher current output say 30 amps by increasing the pass transistors,say 6x 2n3055 jobs with there emmiter ballance resistors , also using a 50a bridge rectifier and 30.000uf filter caps and a lower value current sense resistor?

[coromonadalix]

current sense resistor need to be bigger in wattage / or many in parallel and be recalculated for 30 amp

pre-driver q2  may need to be recalculated and associated parts for more power transistors ....

i would suggest a fan on the power transistors heatsink ...  or even add  switched transformer secondaries  ...

[Zero999]

That old power supply project has errors which need to be corrected first, before you even think about modifying it to increase the current.

Corrected BoM and schematic.


Another potential candidate for U1, U1 and U3 is the TL082H, but I believe it's SMT only, so an adaptor board is required, if you're using the existing PCB or must have through hole.
https://www.ti.com/lit/ds/symlink/tl082h.pdf

[p.larner]

I am aware of the boards faults but i am asking if my train of thought will work if i upgrade the components,basicaly use this as a driver for an existing psu output section? ie 6x 2n3055 pass units with the 0.1 ohm emitter resistors.is the logic behind my thinking ok?,

[coromonadalix]

yes it should work  with minor adjustments

[Zero999]

I am aware of the boards faults but i am asking if my train of thought will work if i upgrade the components,basicaly use this as a driver for an existing psu output section? ie 6x 2n3055 pass units with the 0.1 ohm emitter resistors.is the logic behind my thinking ok?,

I would use more than six 2N3055s, at least eight. Duplicate Q2, Q4, Q5 and the associated emitter resistors another seven times. You might also have to add a pass transistor or another emitter follower to U2, as it's unlikely it'll be able to source enough current. Unfortunately that'll increase the voltage drop a bit, which will reduce the maximum possible output current under full load.

A linear regulator at such a high power level isn't very practical.

[p.larner]

I am starting to build this,the kit came with tl081 opamps,i have some LF357n and some ua748cp opamps,what would be best to use?,thanks in advance.

[coromonadalix]

@Zero999     it depends of the uses

an smps is practical and dissipate a lot less ...   but  can be sensible on inductives or capacitives loads ??


the bests are:  linear and smps or phase controlled  psus  like the Xantrex, Lambda, Sorensen   etc ...

[p.larner]

I dont mean to sound rude but as i already have this,how about actualy giving an answer to my specific question and not go off on a tangent ok,best regards Paul.

[Zero999]

I am starting to build this,the kit came with tl081 opamps,i have some LF357n and some ua748cp opamps,what would be best to use?,thanks in advance.

If you've got the TL081 than obviously use those.

Failing that. The circuit will probably work with any of those, with some modifications.

The UA748 is uncompensated and requires an additional capacitor. The resistor values for the offset nulling circuit will also need to be altered.
https://datasheetspdf.com/mobile/1305449/Fairchild/UA748/1
http://www.elektronikjk.com/elementy_czynne/IC/UA748-3.pdf

The LF357 is frequency compensated but has a different offset nulling scheme.
https://www.mouser.co.uk/datasheet/2/389/ST_LF155D_to_LF357N-1204072.pdf

[p.larner]

can someone tell me how to connect an external rectifier to this?,i have one like an alluminium block with one corner chamfered representing + out from the bridge,can anyone tell me what points to connect what place on the pcb to,a pic would be best,thanks Paul l.

[p.larner]

just to add,i did do this mod with an offboard rectifier a couple of years ago,if i remember i had to cut and bridge some tracks near where the rectifier diodes were on the original pcb,trouble is i cant find the pcb i modded or remember what i did,i can just feed the offboard bridge plus and minus output to the tracks that feed the filter cap,its the part for the minus supply i am stuck at,ie to power the charge pump,also the psu raw power goes too a 22000uf filter cap off board,the voltage on that is 29.6vdc,will 741 or the original tl081 opamps be ok?.