Online Circuit Sim

[W1RKW]

https://www.falstad.com/circuit/

[KD1SH]

  This is pretty cool. I just used it to simulate a simple series-pass regulator, and it worked very well. Of course, it uses the annoying "conventional" current flow theme rather than electron flow, which drives me bat-guano nuts. I learned electronics in the vacuum tube days; show me the electrons!
  Thanks for posting the link; I bookmarked it.

[W1RKW]

Glad you like it.

I use Multisim formerly known as Electronics Workbench which is quite elaborate and if it isn't used regularly, it is easy to forget how to do certain low level things like modeling a component.  But for basic stuff it is very good. It's not easy to get but I managed to get a couple of licenses of the student version when my wife was going to night school many years ago.  I've been modeling low pass filters for an Arduino project I've been working on and off. Out of curiosity I compared Multisim with the online sim and they are very very close so no one should worry about accuracy.

Perhaps Steve or Pete can create a online tools subsection in the Links section for it and other online tools and calculators that members can add too. At some point this will roll off into obscurity.

[KD1SH]

  Yes, I use Multisim 9, myself, and it's very capable, but perhaps a bit too elaborate for very simple circuits. Same for MicroCap 12; awesome program, but complex. I picked up the EWB student version at a college bookstore about twenty years ago; maybe the same version as yours, and though it's a bit "stripped down" compared to the later full MultiSim package, it's easier to use. The only problem is that the old Student version, I think it's version 5.0, won't install on modern operating systems. No big deal, though, I keep an old Windows XP machine in the workshop just for that purpose.
   I consider a good circuit simulator nearly as important as a voltmeter or oscilloscope. I've used MultiSim to design sequencers for amps; grid over-current protection circuits, voltage regulators, bias circuits, and much more. And, often, just for absurdly straightforward stuff, like refreshing my memory about simple circuit functions and such. And it's great when you just want to throw something at the wall to see if it sticks, before getting out the breadboard.

Glad you like it.

I use Multisim formerly known as Electronics Workbench which is quite elaborate and if it isn't used regularly, it is easy to forget how to do certain low level things like modeling a component.  But for basic stuff it is very good. It's not easy to get but I managed to get a couple of licenses of the student version when my wife was going to night school many years ago.  I've been modeling low pass filters for an Arduino project I've been working on and off. Out of curiosity I compared Multisim with the online sim and they are very very close so no one should worry about accuracy.

Perhaps Steve or Pete can create a online tools subsection in the Links section for it and other online tools and calculators that members can add too. At some point this will roll off into obscurity.

[W3SLK]

KD1SH said:

Yes, I use Multisim 9, myself, and it's very capable, but perhaps a bit too elaborate for very simple circuits. Same for MicroCap 12; awesome program, but complex. I picked up the EWB student version at a college bookstore about twenty years ago; maybe the same version as yours, and though it's a bit "stripped down" compared to the later full MultiSim package, it's easier to use. The only problem is that the old Student version, I think it's version 5.0, won't install on modern operating systems. No big deal, though, I keep an old Windows XP machine in the workshop just for that purpose.
   I consider a good circuit simulator nearly as important as a voltmeter or oscilloscope. I've used MultiSim to design sequencers for amps; grid over-current protection circuits, voltage regulators, bias circuits, and much more. And, often, just for absurdly straightforward stuff, like refreshing my memory about simple circuit functions and such. And it's great when you just want to throw something at the wall to see if it sticks, before getting out the breadboard.

I don't know squat about these type of programs. I had Micro Cap but also found it difficult. I went to LT Spice and found that for a dummy load like myself, I can make stuff that operates very closely to what I make on the bench. I got onto this website and took a few lessons: http://www.funwithtubes.net/  I did some basic powersupply simulations that were spot on. As always, your mileage may vary!

[W1RKW]

I had EWB years ago and like you, it would only work with earlier OSs.  Hated to toss it in the trash but that's the way it goes.  It wasn't long after that I got my hands on Multisim. I don't think there is a stark difference between version 9, 11 and 14 other than the list of components.  I have versions 11 and 14.  Version 14 has maybe 2 dozen receiving vacuum tubes in it.  Version 11 only has 3 or 4. I never tried modeling a circuit with a tube. 

I learned on  PSPice using DOS as the OS. That's going way back. I couldn't do it now if my life depended on it. 40 years later it fell out of my brain some where along the way.

I installed and tried Microcap. I soon removed it from my system. It worked a bit different compared to Multisim and I didn't want to relearn how to ride a bike again as it were. And I figured why do I need 2 applications that do essentially the same thing. I still have it though as a fall back. Same with LTSpice. Can't teach an old dog new tricks.

  Yes, I use Multisim 9, myself, and it's very capable, but perhaps a bit too elaborate for very simple circuits. Same for MicroCap 12; awesome program, but complex. I picked up the EWB student version at a college bookstore about twenty years ago; maybe the same version as yours, and though it's a bit "stripped down" compared to the later full MultiSim package, it's easier to use. The only problem is that the old Student version, I think it's version 5.0, won't install on modern operating systems. No big deal, though, I keep an old Windows XP machine in the workshop just for that purpose.
   I consider a good circuit simulator nearly as important as a voltmeter or oscilloscope. I've used MultiSim to design sequencers for amps; grid over-current protection circuits, voltage regulators, bias circuits, and much more. And, often, just for absurdly straightforward stuff, like refreshing my memory about simple circuit functions and such. And it's great when you just want to throw something at the wall to see if it sticks, before getting out the breadboard.

[KD1SH]

  My MultiSim 9 has 22 tube models, but I've done little with them. When I get better at creating my own models, I'm going to try modeling 813's and 810's, and maybe 4D32's.
  I do love the spiffy virtual Tektronix scope; I think version 9 was the first version to include that, but I'm not sure.
  I love using circuit simulators, but, despite my having done a brief stint in IT as a desktop support tech, I'm admittedly not the absolute whiz with sophisticated software packages. I did a little Visual Basic programming at a community college; I can mess around a bit with programming PIC Microcontrollers, but as a real "power user" with any sort of CAD type program, I fall short. I've been trying lately to get up to speed with PCB layout software, but so far I haven't done anything worth sending Gerber files off to a board house.

I had EWB years ago and like you, it would only work with earlier OSs.  Hated to toss it in the trash but that's the way it goes.  It wasn't long after that I got my hands on Multisim. I don't think there is a stark difference between version 9, 11 and 14 other than the list of components.  I have versions 11 and 14.  Version 14 has maybe 2 dozen receiving vacuum tubes in it.  Version 11 only has 3 or 4. I never tried modeling a circuit with a tube. 

I learned on  PSPice using DOS as the OS. That's going way back. I couldn't do it now if my life depended on it. 40 years later it fell out of my brain some where along the way.

I installed and tried Microcap. I soon removed it from my system. It worked a bit different compared to Multisim and I didn't want to relearn how to ride a bike again as it were. And I figured why do I need 2 applications that do essentially the same thing. I still have it though as a fall back. Same with LTSpice. Can't teach an old dog new tricks.

  Yes, I use Multisim 9, myself, and it's very capable, but perhaps a bit too elaborate for very simple circuits. Same for MicroCap 12; awesome program, but complex. I picked up the EWB student version at a college bookstore about twenty years ago; maybe the same version as yours, and though it's a bit "stripped down" compared to the later full MultiSim package, it's easier to use. The only problem is that the old Student version, I think it's version 5.0, won't install on modern operating systems. No big deal, though, I keep an old Windows XP machine in the workshop just for that purpose.
   I consider a good circuit simulator nearly as important as a voltmeter or oscilloscope. I've used MultiSim to design sequencers for amps; grid over-current protection circuits, voltage regulators, bias circuits, and much more. And, often, just for absurdly straightforward stuff, like refreshing my memory about simple circuit functions and such. And it's great when you just want to throw something at the wall to see if it sticks, before getting out the breadboard.

[W3SLK]

KD1SH said:

My MultiSim 9 has 22 tube models, but I've done little with them. When I get better at creating my own models, I'm going to try modeling 813's and 810's, and maybe 4D32's.
  I do love the spiffy virtual Tektronix scope; I think version 9 was the first version to include that, but I'm not sure.
  I love using circuit simulators, but, despite my having done a brief stint in IT as a desktop support tech, I'm admittedly not the absolute whiz with sophisticated software packages. I did a little Visual Basic programming at a community college; I can mess around a bit with programming PIC Microcontrollers, but as a real "power user" with any sort of CAD type program, I fall short. I've been trying lately to get up to speed with PCB layout software, but so far I haven't done anything worth sending Gerber files off to a board house.

That is the big thing lacking in LT Spice: tube characteristics. I have visited a couple of the audiophool websites and got directions on how to change them. That was several years ago and I was unsuccessful, so that project withered on the vine.

[W1RKW]

I tried modeling a tube and a MOSFET in Multisim a while back. Neither of which worked. It was complicated. There were to many steps and there was language I did not understand so I gave up.

[KA3EKH]

Man am I stupid, been trying to understand just what thus application is? lots of neat wave forms and squiggles with color lines and the like but don't see the point? Lot of basic design block stuff and imagine if you don't know how to build a power supply or amplifier its useful but beyond that what do you do with it? Example, I have to build a PA tank for a plate modulated 807 running 500 volts using an existing 500 pf variable capacitor and a coil that I will trial and error together out of parts from the junk box. Can this app draw something up for me? Already have something in the back of my mind but can this app show me a better way? maybe something like AI dose when researching or looking up something? but being a man of my limited capability would not know how to start using this thing.
I will say that I wasted a couple hours playing around with the logic circuit simulators and endless fun with the circular membrane wave simulator, have no idea what its for but fun to play with.

[KD1SH]

   No, it's not any sort of AI, and can't "design" anything for you; not even the simplest circuit. It still requires you to know how the components function and understand the basic concepts.
   Think of it as a sheet of magic paper that comes with an equally magic pencil. With that magic pencil, you draw a schematic of your circuit on the magic paper. The difference between an ordinary schematic and your magic schematic is that the magic one actually works, at least in your computer's virtual world. You can insert virtual "magic" test equipment into your circuit, and watch it function, or not function if you've made mistakes.
   It's like building a circuit on a breadboard, but whereas with a breadboard, you need the actual components and wires, power supplies, and test equipment, you don't need any of that with the simulator.
   Look around on YouTube and you'll find plenty of videos demonstrating various circuit simulators. Some are challenging to learn, and others quite simple, but none of them are substitutes for knowing your electronics.

Man am I stupid, been trying to understand just what thus application is? lots of neat wave forms and squiggles with color lines and the like but don't see the point? Lot of basic design block stuff and imagine if you don't know how to build a power supply or amplifier its useful but beyond that what do you do with it? Example, I have to build a PA tank for a plate modulated 807 running 500 volts using an existing 500 pf variable capacitor and a coil that I will trial and error together out of parts from the junk box. Can this app draw something up for me? Already have something in the back of my mind but can this app show me a better way? maybe something like AI dose when researching or looking up something? but being a man of my limited capability would not know how to start using this thing.
I will say that I wasted a couple hours playing around with the logic circuit simulators and endless fun with the circular membrane wave simulator, have no idea what its for but fun to play with.

[W3SLK]

KD1SH said:

   No, it's not any sort of AI, and can't "design" anything for you; not even the simplest circuit. It still requires you to know how the components function and understand the basic concepts.
   Think of it as a sheet of magic paper that comes with an equally magic pencil. With that magic pencil, you draw a schematic of your circuit on the magic paper. The difference between an ordinary schematic and your magic schematic is that the magic one actually works, at least in your computer's virtual world. You can insert virtual "magic" test equipment into your circuit, and watch it function, or not function if you've made mistakes.
   It's like building a circuit on a breadboard, but whereas with a breadboard, you need the actual components and wires, power supplies, and test equipment, you don't need any of that with the simulator.
   Look around on YouTube and you'll find plenty of videos demonstrating various circuit simulators. Some are challenging to learn, and others quite simple, but none of them are substitutes for knowing your electronics.

The problem with most SIM programs is they just don't have the data for using tube components. Like I said previously, visit some of the audiophool websites.  Maybe you can make 'heads and tails'  of how to compile that tube data for usage in something like LTSPICE. I think there are tubes like 807's 6SN7's and I thought 811's also. If you do figure it out, let us know because I would love to apply the same thing for some ideas I have cooking!

[Opcom]

I've tried to add tubes to LTspice, tried to follow the directions that do not seem complete and do not seem to work, and stopped wasting time trying to get it to work.

[W3SLK]

Opcom said:

I've tried to add tubes to LTspice, tried to follow the directions that do not seem complete and do not seem to work, and stopped wasting time trying to get it to work.

Good! I'm glad it's not only me!

[W4AMV]

You can add tubes to LTspice. There are audio folks who have spent effort in modeling the tube IV reasonably well. There are limits, as class C and grid current conduction are not usually considered. Note, the spice directive is added as shown here and some of the model directives must be modified. The ^ carrot symbols must be changed to **, or *. Here is a 6L6 example.

[W4AMV]

I should add, a good idea is to check the accuracy of the model via the IV traces for the tube. Sweep with two voltage generators, the grid and plate while monitoring the grid and plate current. Use the same sweep range and increments as the data sheet. Shown here is a type 10 tube with the notion of looking at a push pull power oscillator. Setup is straightforward. Glad to outline process.

[Tom WA3KLR]

Alan, try this to pass the LTSpice file here: Take that .asc file and make a copy, change the file extension to .doc (or any the forum accepts) and post it here. See if we can grab the .doc file, save it, and change back to .asc so we don't have to type in all that.

[W4AMV]

Alan, try this to pass the LTSpice file here: Take that .asc file and make a copy, change the file extension to .doc (or any the forum accepts) and post it here. See if we can grab the .doc file, save it, and change back to .asc so we don't have to type in all that.

Good day Tim.

Sending a LTspice file to a forum is best accomplished by zipping the file(s) into a folder. If I was to send you directly this .asc file, it would be straightforward and operate with no issue. All symbols and netlist are self contained in the .asc file. The model for the 6L6 is in the spice directive and I have attached that here as a text file. The remaining circuit description is simply LTspice. All you need to do is copy that text file into your spice directive and add your tube symbol from the LTspice component library. Rename that tube symbol to 6L6. And construct the circuit in the usual manner.

I tried you suggestions just to be sure, and that approach does not work.

[W3SLK]

W4AMV said:

Good day Tim.

Sending a LTspice file to a forum is best accomplished by zipping the file(s) into a folder. If I was to send you directly this .asc file, it would be straightforward and operate with no issue. All symbols and netlist are self contained in the .asc file. The model for the 6L6 is in the spice directive and I have attached that here as a text file. The remaining circuit description is simply LTspice. All you need to do is copy that text file into your spice directive and add your tube symbol from the LTspice component library. Rename that tube symbol to 6L6. And construct the circuit in the usual manner.

I tried you suggestions just to be sure, and that approach does not work.

I will have to try that. I have all the 'Nakabayashi' tube files, but they are listed in an INC format.

[Tom WA3KLR]

OK Alan. I opened your text file and copied that, pasted it into the .Op (Spice directive dialog box) and it is in a schematic, so I have that now, thanks!
I haven't run it yet, I have other things to do today.

[W4AMV]

Very good all.

Do not forget to call out the symbol as a 6L6_AN. There are a variety of 6L6 units including metal and glass. You can do 3 generator V sweeps so the screen can be swept as well. It pays to have the data sheet in front of you and sweep the exact same range as the sheet and compare. I did the plate and grid only here while holding the screen constant.

The model files I have found are quite extensive. And of course if you desire, you can make your own as there are tools available.

[W4AMV]

I will have to try that. I have all the 'Nakabayashi' tube files, but they are listed in an INC format.

The INC format will work, however, all ^ symbols must be changed to **

73' Alan

[W3SLK]

W4AMV said:

The INC format will work, however, all ^ symbols must be changed to **

Thank you! I will give that a try once I return to it!

[W4AMV]

Here is the 6L6 with data sheet and sim to compare.

Desire to set scales and sweeps to align with the data sheet formats.

[Opcom]

I had no idea the INC or converted to TXT file contents were to be pasted into the LTspice window as a spice directive. I have never seen that or been told to do it until this example.

It works fine after I removed the heater portion of my tube symbol. I'm very gratified with this. With the heater, the following error shows up because there are too many pins.

-----------------------------------
Port(pin) count mismatch between the definition of subcircuit "6l6_an" and instance: "xu2"
 
The instance has more connection terminals than the definition.
-----------------------------------