U47 with EF14 tube Build

[Spencerleehorton]

I will do my best to explain without hopefully confusing you.
I am trying to feed a AC voltage source into a diodes to show the correct dc voltage.
I have tried to create transformers from the inductors but the coupling command K L1 L2 1 doesn’t seem to do anything?
So with this not working I have just used the dc voltage of what I have multiplied by the 1.4v to give the dc which I would have.
LTspice is very new to me and I know your a lot more skilled with “The basics” than I am but it’s still quite a learning curve to solve all this, any help would very much be appreciated

 

[Khron]

Yes, BUT you insist / expect those node labels to show you the voltage at anything else than moment zero - i'm not sure (kinda doubt) LTspice can do that.

If you can let go of that requirement, you should be able to have that voltage doubler arrangement working with a sine source at the input (WITHOUT any DC offsets - don't those defeat the whole point?).

That, or see how you can get a Windows virtual machine running on your Mac, to hopefully avoid LTspice having any hissy-fits.

 

[Spencerleehorton]

i have installed ltspice via wineskin and its giving me the same run aound? older windows version 17

 

[Spencerleehorton]

within LTspice im not quite sure what a dc offset means as regards the sine voltage but when nothing is put in there the voltages are completly screwed, so it has to have it in there as well as the gnd on the H+ voltage source on the negative? which as we have already said shouldnt be on there.

I have informed LTspice support about all this and will wait to see what they come back with as there seems to be many problems with this actual arrangement within LTspice.
other sims seem to work fine, im on OSX sonoma and have LTspice 17.1.5 mac. previous versions didnt seem to have this problem.

 

[Khron]

within LTspice im not quite sure what a dc offset means as regards the sine voltage but when nothing is put in there the voltages are completly screwed

You mean the ones resulting from the ".op" simulation (where the node labels source their numbers from), which finds the DC operating points for the simulated circuit? That will obviously give you pretty much nothing, zero, nada, because the sine source starts from 0V. As such, as you've seen in both my and your ".tran" (transient) simulation, it takes a while for the rectified and smoothed voltage to reach the max level it can and does.

As i wrote in my previous reply...

If you can let go of that requirement, you should be able to have that voltage doubler arrangement working with a sine source at the input (WITHOUT any DC offsets - don't those defeat the whole point?).

"That requirement" being the node labels showing you the DC voltages (which START FROM ZERO)...

LTspice 17.1.5 mac. previous versions didnt seem to have this problem.

Have you had reason to simulate such circuits in the previous version?

"DC offset" means exactly what the words say, in the context of a sinewave.
- With 0V DC offset, a 1Vpeak (2Vpp) sinewave crosses through 0V twice per period.
- With 5V DC offset, a 1Vpeak (2Vpp) sinewave never crosses through 0V; its "mid-point" (so-to-speak) is the value of the DC offset, so the sinewave swings between +4V and +6V

... Which means that voltage doubler you were attempting to simulate does precisely diddly-squat; the sine "only" gets rectified (half-wave?), superimposed on top of whatever DC offset you set.

Just forget those blasted node labels; probe the nodes when the transient simulation is over, and read your end-voltages from there. Sure, those labels are convenient, but they don't work the way you want them to. I'm willing to bet that the readings from the completed simulation DO actually look much more like they're supposed to, even if the quiescent condition DC voltages do not (as one might expect, since we're dealing with AC-coupled circuitry).

 

[terry setter]

You might want to consider increasing C4 and C6 by a factor of 1000 or so. You'll get quite a bit less ripple.

You could substitute a 500 Ohm or a 1000 Ohm pot for R4 and R5 (wiper to "ADJ" on the 317). Then you could set the output voltage where ever you want it (within the limits of the supply and the 317).

Does D6 pull the output of V2 to ground 50% of the time?

 

[rock soderstrom]

You might want to consider increasing C4 and C6 by a factor of 1000 or so. You'll get quite a bit less ripple.

Hi Terry, what schematic are you referring to with your designations?

 

[Spencerleehorton]

well i still have the gnd attached to the neg voltage (which is wrong) but i have changed all the caps to not have the uf or nf and the voltages readings are now seeming to work!!??
i still havent managed to figure out how to make the ac voltage into a inductor work and get the diodes doing their 1.4v thang?

 

[rock soderstrom]

I can't help you with the Spice stuff but what tube are you planning to use the power supply for? Still EF14 or also others? The EF14 has a current consumption of 0.47A, more than the other usual suspects. I would simulate that first, you are working with 0.3A at the moment.

 

[Spencerleehorton]

no im going to use EF80 and EF800 which are 0.300 and 0.275mA, i also need a tad more for the polar pattern feed but thats off the B+.
i have just managed to get a inductor working as a transformer so a small step forward.

 

[rock soderstrom]

no im going to use EF80 and EF800 which are 0.300 and 0.275mA, i also need a tad more for the polar pattern feed.
i have just managed to get a inductor working as a transformer so a small step forward.

Okay, then it is spot on. I came up with it since we are in the "U47 with EF14 tube Build" thread. Nothing is more constant than change.

 

[Khron]

i have changed all the caps to not have the uf or nf

Yeah, that made the caps have values in FARADS (not micro 10e-6 or nano 10e-9). Prefixes and suffixes are there for a GOOD reason, in engineering.

I'm completely aware i'm likely getting way more worked up about this than i should, but i feel compelled to once again ask - just what the h*ll ARE you attempting to achieve with these LTspice sims???

If you really don't care*** to verify the workings of that voltage doubler at the input of the heater voltage regulator, just delete that whole diode-capacitor arrangement, and feed that part of the circuit with a straight DC source.

*** By adding an arbitrary 16V DC offset to that, that renders the voltage doubler side of things (the two diodes and 10000 microfarad, or now 10000 farad!!!!! capacitors) null and void. That's why you "need" to ground the negative side of that "sinewave" source, in order to get those node label readings to show meaningful numbers right at the start of the simulation, before the transient part of the simulation even begins.

If you're gonna fudge the numbers just so some arbitrary (irrelevant, unrealistic, "cosmetic") readings show up on your display the way you want them to, what is even the point of these sims?



Later edit: Those node label voltage readings are taken from the DC operating point simulation results, which is performed FIRST, before starting the transient / AC simulation stage.

https://ltwiki.org/LTspiceHelp/LTspiceHelp/_OP_Find_the_DC_operating_point.htm

Perform a DC operating point solution with capacitances open circuited and inductances short circuited.

 

[Spencerleehorton]

It such a shame you are so negative sometimes and jump to the “why” it almost feels like your trying to put me down as I clearly don’t know what I’m doing!!! lol!! But alas I am learning.

I’m am just trying to figure out this ,
it’s just as simple as that.
Going forward I’d like to simulate circuits so a. ) I understand it a bit more and
b. )When testing it gives me a more accurate voltage figures to get.

I apologise for any offence my journey has towards your greater experience and wisdom.

 

[Khron]

I'm "so negative" because despite trying to help, it's not easy when my advice gets seemingly disregarded apparently only in order to achieve cosmetically "pretty" results (looking at you, voltage labels).

My mind was just irritated by the (claimed) intention of learning / testing how a circuit works, while making sure that a completely different circuit with different settings was being simulated. Does that perhaps begin to explain the roots of my frustration?

My intention was definitely not to put you down or discourage you, but it's really difficult to stay (that) positive in the face of... what, from the outside, came across as bordering on stubbornness and/or gaslighting, as unintentional as that may have been.

- "I'm not getting the voltage labels i want, when i'm simulating this circuit"
- "Those labels can't and won't ever show you the numbers you'd prefer, if you want your simulation to be even in the same ballpark as 'accurate' or 'realistic'..."
- "Well, i still fudged the input data so that the labels look nice"
- "Ok, but what's the point of this whole exercise then???"

And yes, i'm very much a "why?" guy, because not enough people seem to ask themselves (or answer truthfully to) that.

You've caused me no offense; if anything, the fault was / is mine for possibly being too determined to try to help you avoid deluding yourself (for the wrong reasons anyway), or to blame tools for them being used "wrong".

Yes, you're trying to figure out this, while (seemingly) refusing to listen to / accept facts LTspice works (only) the way it does, and no amount of wishful thinking will help that, unfortunately.

I promise you I did not intend to derail this thread or to end up ranting, but i also couldn't not (at least attempt to) explain my view and the reasons for writing what i have. I sincerely hope you can understand that, if not even appreciate it (I won't blame you if you can't / don't, though)

 

[Spencerleehorton]

yep all fair thoughts and appreciate where your coming from, probably best that i dont ask anymore LTspice questions!!!

 

[Khron]

I appreciate your understanding

"The only stupid questions are the ones left unasked". It's the not accepting demonstrably true answers that irked me

 

[Spencerleehorton]

this way the TXF and the PCB would fit nicely into the smaller enclosure


Im going to use the bigger ones for these anyways



All seems to work as it should, unloaded im getting 180v dc on B+ and 15v dc on H+, will test with load resistor as well 133k B+ and 20R H+

 

[rock soderstrom]

Ohh, I am so proud, the first time ever someone uses one of my designs! Thank you Spencer!

Keep an eye on R10 in the B+ part, it will get warm depending on the current you apply to the LED.

 

[Khron]

... Although that black power switch looks like it panel-mounts from the outside of the case

 

[rock soderstrom]

All seems to work as it should, unloaded im getting 180v dc on B+ and 15v dc on H+, will test with load resistor as well 133k B+ and 20R H+

Yep, you might have to adjust R7-R9 a bit, the test with load will show.
Keep us posted