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Rookie LTspice simulation and build of TAE linear PSU using LT1028C help

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denimdragon:
I'm attempting to build a dual rail linear power supply based on the one in TAE pg. 608 Fig. 9.15, but I'm using 2 LT1028CN instead of the OP27, and I'm omitting the TLV431 (down to zero) and also instead of the +5 VCC on A2 I'm running the rail directly off the 30V rail just as A1. The reason I'm using this is because I don't have a dual pot right now and I need this psu for other projects using op-amps.

It simulates fine but that could be a gotcha. My LTspice skills are minimal at best, but they are decent enough for me to use it as a tool to see if I am thinking in the right direction. Other than the LT1028s I have on hand, I also have a couple of LT1002s which I thought about using as the LT1028s or considerable more expensive, but I want the PSU to be the best I can do currently.

Any help/advice would be appreciated before I finish it up and make a "whoops".



Kleinstein:
The right OP for this circuit with low voltages would be something like the LM358 (or cheaper   :D).

At high voltage one may need to use 2 single OPs and separate lower supplies (e.g. -5 V for the 1 st OP and +5 V for the negative side OP) to avoid special high voltage OPs. The LT1028 would be a poor choice - in the given circuit it is not even low noise.

denimdragon:

--- Quote from: Kleinstein on August 27, 2019, 11:31:30 am ---The right OP for this circuit with low voltages would be something like the LM358 (or cheaper   :D).

At high voltage one may need to use 2 single OPs and separate lower supplies (e.g. -5 V for the 1 st OP and +5 V for the negative side OP) to avoid special high voltage OPs. The LT1028 would be a poor choice - in the given circuit it is not even low noise.

--- End quote ---

I think I can salvage a LM358 and maybe some UA741s from some old projects that I no longer use. I'll see what I can come up with. Thanks again.

I'm also attaching a screen shot of the circuit in case others want to ad there expertise with open up LTspice.

SiliconWizard:
Is your input supply +/-15V or +/-30V? ::)

denimdragon:

--- Quote from: SiliconWizard on August 27, 2019, 06:25:12 pm ---Is your input supply +/-15V or +/-30V? ::)

--- End quote ---

Ah, yeah. That voltage source model is one I grabbed from Yahoo usergroup. Very handy but ambiguous. It's +/- 30V. That's a rough calculation based on my transformer measurements from a little one I grab from an old BKPrecision pulse generator. Now I'm contemplating on using a bigger transformer that I salvaged from an Onkyo TX-21. It's a tank with one primary and two secondary windings. The configuration is a bit confusing as I've not seen a transformer with this particular layout, but my measurements show that the largest secondary has 25V-0-25V which comes out to around 35ish volts. I think I really want to use it versus the little one from the BKPrecision.

I'm thinking I could use the main secondary for my adjustable source for the LM317/337 pair and the lesser voltages to run a fixed +/-12V, +/-9V, +/-5V for quick school projects with no fiddling. This started off as a somewhat quick build for school, but now I've kind of committed myself to make a decent PSU that I can be proud of and use with all my projects. I have a Tektronix PS282 (linear) 0-18V 0-5A and a BKPecision 0-18V 0-5A (Switcher that I use for LabVIEW projects) but I don't have anything dual pole.

I'm planing on housing it in an old EVGA PSU housing that has the right amount of space and a huge fan on top to keep things cool as there will be intense thermals with 8 regulators. The other regulators for the fixed voltages are TO-220F packages so I figure I can mount them on the chassis for heat evacuation.

All this is speculative as I am a rookie to designing electronics systems so if I said something stupid or incorrect, please correct me. I wanna be great at this so my pride and ego are in my pocket.  :-+ See transformer pics below.

P.S. Tomorrow I will have access to ICs and other components (standard stuff but mostly new old stock, some REALLY old stock) so if anyone has some suggestions for other parts other than the LM358, please let me know as I can grab them while I'm there. Thanks again.

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