PSU Voltage Adjustment

Thread Starter

JulesP

Joined Dec 7, 2018
383
hi,
The keyboard F2 is the LTS key for calling up the Component menu.
E
Hi E,
I loaded up your file but found that it could not load/show the pot so there’s a big gap in the circuit and my component list does not seem to show one for me to include. I presume I have to add to the component library from somewhere?

Yahoo groups have now been shutdown so their libraries are no longer available. Are you able to export a component?

see pic
504A8686-E285-4B82-B2E4-2BA366D3F5AE.jpeg1078293F-E392-4C44-9625-681B6025E997.jpeg
 
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Thread Starter

JulesP

Joined Dec 7, 2018
383
hi J,
Unzip this file, also has a thermistor example.
E
Hi E,

I'm struggling to incorporate your pot into my circuit, or any circuit. If I open your potentiometer spice symbol file I'm unable to copy and paste it into my circuit and it will only let me copy and paste (i.e. duplicate) into the original file. If instead, I incorporate the text from the SUB file into my circuit (see pic) then it seems I'm still required to have a generic pot in the circuit to be able to modify it with the specifics in the SUB file, which I don't have. Catch 22!

Any advice on how to proceed would be appreciated.

J
Pic-1.jpg
 

ericgibbs

Joined Jan 29, 2010
19,078
hi,
Have you placed the potentiometer.sub in Documents/LTspiceXVII/ lib/sub file and the potentiometer.asy in the Documents/LTpiceXVII/ lib/sym file.??

Then the potentiometer.asy file should be shown in the F4 pop up menu for components.

You may have to restart LTS after making these changes.

E
 

Thread Starter

JulesP

Joined Dec 7, 2018
383
hi,
Have you placed the potentiometer.sub in Documents/LTspiceXVII/ lib/sub file and the potentiometer.asy in the Documents/LTpiceXVII/ lib/sym file.??

Then the potentiometer.asy file should be shown in the F4 pop up menu for components.

You may have to restart LTS after making these changes.

E
Aha it was in the main folder. Will try that
 

Thread Starter

JulesP

Joined Dec 7, 2018
383
hi,
You should have a file path as per this image when using Windows
E
View attachment 227932
I have the pot in the circuit now and shows under F2 (not F4) listing. There are various statements in your 'Pot Test 1' file such as '.include potentiometer.sub' and the longer '.SUBCKT NTC etc statement'. Do I still need those?

Also, would a DC sweep be the appropriate simulation analysis with a straightforward 12V DC supply? The pot arm is set to 0.5 of travel so I'm thinking that I need to programme that to change to give the Gate input range as you did early on.

Pic-2.jpg
 

ericgibbs

Joined Jan 29, 2010
19,078
hi J,
You must have the .include potentiometer.sub on your circuit
The SUBCKT NTC, and the thermistor ,I would delete those. you want only the pot.

E
 

Thread Starter

JulesP

Joined Dec 7, 2018
383
hi J,
Just in case you still have a problem, I have downloaded this pot zip from the LTS user group.
Tested it OK.
E
Hi E,

I will have a go with writing the correct syntax over weekend and obtaining some plots and will report back on Monday. Meanwhile this link takes you to a short video of what I’m using this voltage adjustment for when attached to the PWM supply to feed various electrolysers.

https://www.dropbox.com/sh/k7d5ocyh4r2z2f8/AAAlokQIWuyXenJtLEhTyagha?dl=0
 

Thread Starter

JulesP

Joined Dec 7, 2018
383
hi J,
Just in case you still have a problem, I have downloaded this pot zip from the LTS user group.
Tested it OK.
E
Hi E,

Thank you. Having got the pot working I found it nice and easy to switch FETs and see how Vout changes with Vg. I attach two such results and the IRF6201 seems a good choice.

I'm assuming the Vout takes into account the voltage drop arising from the actual current flow so it's 'real' in that sense.

I didn't need to use the 'include' statement on the schematic, perhaps due to my having the .asy file sitting in the appropriate folder? I've seen some videos of people importing the SUBCKT text into Spice and then creating a component out of that so I must have the equivalent with the files you sent me.

Again it's not an efficient way to produce the voltage I need but for the purpose of testing the effect on gas production it will do and if I need in the future to produce a power supply with a similar range of voltage and current demand I expect it can be done better using LM338 regulators in parallel. If I get to that stage I will consult :)

J

IRF6201.jpgIXTK200N10P.jpg
 

Thread Starter

JulesP

Joined Dec 7, 2018
383
hi J,
Like to have a copy of your asc file, if that's OK.
Maybe for future collaboration on the project.
E
Sure but it's on my Windows laptop and I normally use a Mac, which I'm on now, so will sort later today.

I have found that the IRF6201 in no longer made and is SMD anyway to I will have to go for the IXTK 200N10P that is £10 a piece. :oops:
 

Thread Starter

JulesP

Joined Dec 7, 2018
383
Hi E,

I attach all the files related to that circuit and one grab showing Vout at about 10V which is useful.

When choosing an appropriate FET, besides issues like the package, I checked on the datasheet to see what the max continuous current is. For the AO6408 it's just under 9A and yet the graph (attached) shows around 40A. How can I reconcile these? Yes, the AO6408 can take pulses of 40A but the I assume the graph shows continuous values.

J
AO6408.jpg
 

Attachments

Thread Starter

JulesP

Joined Dec 7, 2018
383
Hi E,

While I'm on the topic of voltage regulation, I'm exploring an option using LM338s that may be better in the long term and attach my version of it here. I will have a go at simulating it in LTS but it will take me a while.:oops:

LM338 Regulator Circuit.jpeg
 

Thread Starter

JulesP

Joined Dec 7, 2018
383
hi J,
Where did you get that post #37 circuit, its yuk!

This is LTS with just one LM338 to check out the design.
E
It’s my copy of the circuit at the link shown on the drawing. I will get you a live link. I’ll explore your attachments thanks
 
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