The Shocktave in CircuitMaker

[Paul Marossy]

Just for fun, I created a Shocktave schematic in CircuitMaker 6 Student Version 'cause I wanted to see what was going on in that circuit. The funny thing is that I don't see an octave effect going on anywhere in the circuit when I was running the simulation on it. All I see with the "scope probe" is sine waves. :?

Anyone else try this, and if so, what am I doing wrong?! Or am I doing anything wrong? I am a little perplexed...

[Arno van der Heijden]

You need to do a Fourier analysis to visualize the harmonic content of the signal.
If everything is ok, you will see the 2nd harmonic jump out.

[Joe Davisson]

FWIW, it's an octave-down. Try taking out the mix control and check one of the collectors in the oscillator section for the output. Don't know much about simulators like that.

[bryantabuteau]

I imagine you forgot to simulate the stomp switch, and its not turned on

[Paul Marossy]

Thanks for the replies guys. I'm still trying to understand this program. I'm just not seeing what I would expect on a lot of the circuits I have simulated. I guess I need to use my real oscilloscope to compare to CircuitMaker and so I can get my bearings. This Fourier ananlysis thing still has me a little confused. I guess I need to read up on that...  :?

[j0shua]

I use circuitmaker , the student version is not 100% complete, and need to be updated , for example you can't use LM386 in circuit maker because don't have on database , but you can use Lt101 or LT102 to simulated....

to run a test you need to put the complete value and switch on-off to create the complete test , Btw some times caps on jack cause errors on test runs  :oops:

[Paul Marossy]

to run a test you need to put the complete value and switch on-off to create the complete test

OK, that sort of makes sense. How do you switch it on/off?

[j0shua]

In the search Componets you can look for switch , just type this ----------------------> NC PushButton  and you get the switch    ---o | o---
                                                                                    -----

the simbol i draw appears

[Paul Marossy]

Ok, I'll give that a try.

[lovekraft0]

If you got the entire circuit to sim, you're doing better than I have - I had to remove the input emitter follower and gain stage and the mix control just to get SPICE to digest it, so I replaced them with a pulse waveform from the signal generator, and I've definitely got the subharmonic showing up strong on the Fourier analysis! You'll have to set the Fourier frequency to half the input frequency in order to see it. With a 500Hz square wave input between 0 to +5v and 0 to +8v, I'm showing the 250Hz subharmonic level at about 6dB above the fundamental, and a strong harmonic at 750 Hz that's at about the same level as the fundamental. Now I'm gonna have to build one of these!! Thanks, Joe, it's a very cool idea!

[Paul Marossy]

lovecraft0-

I'm still getting sine waves all over the place when I sim the circuit. I was thinking yesterday that I should try a pulse instead of a steady sine wave, but didn't actually try it. I think I'm going to do that next. Do you happen to remember what parameters you used?

BTW, I've got every circuit that I have simulated to work so far (in their entireity)-

Modified Black Cat OD-1
Octal Fatness Tube Amp (gave me some trouble)
Shocktave (well, not like I expected it to)
Howie's Metal Simplex
Tillman's FET preamp
Modified Tillman FET preamp
And a couple of others that will have to remain a secret  :wink:

[Arno van der Heijden]

Paul,

Like I suggested before, you can only see the harmonic content (and consequently octave up or down) when you do a Fourier analysis. A sine wave which is doubled in octave is just a sine wave with a frequency that's twice as high. The same goes for octave down.

So, you have to go to experimental setup (or something similar... don't have the program in front of me right now) and check the box that says 'Fourier analysis'. Then, you have to give in the fundamental frequency and I think you should take half the input frequency, like lovekraft0 suggested.

Then, when you do an analysis, you will get the frequency spectrum in harmonics of the fundamental frequency. What you should expect to see is that the fundamental, which is actually an octave down from your input, is dominant.

[Paul Marossy]

You know, I was thinking that this was a full wave rectification effect, but it's really a half-wave rectification effect, correct? That's probably why I have been a little confused...  :oops:

I'm still not getting this Fourier Analysis part, though. I only see one spike at the fundamental frequency. What I am I doing wrong?!

[Arno van der Heijden]

I'm still not getting this Fourier Analysis part, though. I only see one spike at the fundamental frequency.

That's the nature of Fourier Analysis. You only get spikes at the fundamental and its harmonics (in theory, without signal leakage). The length of a spike is a measure for the contribution of the particular harmonic to the signal.

We're dealing with an octave down effect here, so if you chose the fundamental frequency to be half your input frequency, you should indeed get a big spike at the fundamental frequency. That would mean that your measured signal is half the frequency of your input frequency.

Some more information on Fourier analysis:
http://www.astro-med.com/knowledge/fourier.html

[lovekraft0]

Paul, you've got mail - let me know if that helps.

[Paul Marossy]

Thanks Arno,

I'll be reading up on that Fourier Analysis!  

lovecraft0-

Thanks!  

[Paul Marossy]

Well, thanks to lovecraft0, I have identified the problem:

If you have a component such as a 1 megohm resistor, and you just enter "1M", it doesn't recognize it as a 1 megohm resistor, but rather a 1 milliohm resistor. You have to enter "1meg" and then it works! Now I am seeing what I would expect to see on a real 'scope. I wish the @$%&(! manual would make that clear.  :x

Thanks lovecraft0!  

[Arno van der Heijden]

What do you see? Something like a square wave, half the input frequency?

[Paul Marossy]

I'm not totally sure how to interpret this, but here is the output waveform with a 440Hz 200mV peak amplitude sine wave at the input, gain control at 80%, blend at 1% and volume at 99%.



And here is the output waveform with a 440Hz 200mV peak amplitude sine wave at the input, gain control at 1%, blend at 1% and volume at 99%. It looks kinda like an octave to me, I think...

On both of these settings, I used 5mS start time, 25mS stop time.