fwiw: ltspice demo of the DOD Overdrive 250 circuit on gaussmarkov.net

[gaussmarkov]

there have been a few questions about how the circuit in this project works.  one way to learn is to use a SPICE simulator like LTSpice/SwitcherCAD III.  you can see some of the capabilities of LTSpice in a demo run on gaussmarkov.net.  i show how to see the clipping from the diodes, the clipping from the op amp, how to find the input impedance, and how to see the overall frequency response of the circuit.

see LTSpice Analysis and the DOD Overdrive 250.

all the best, gm

[frankclarke]

This is the CircuitLogix sim of the DOD250:

Sim File: http://www.guitar-pedals-effects.com/DOD250.ckt
Screenshot: http://www.guitar-pedals-effects.com/DOD250.jpg


http://www.circuitlogix.com/student_version.html

[gaussmarkov]

This is the CircuitLogix sim of the DOD250:

Sim File: http://www.guitar-pedals-effects.com/DOD250.ckt
Screenshot: http://www.guitar-pedals-effects.com/DOD250.jpg

http://www.circuitlogix.com/student_version.html

wonderful!   i will have to check this out.  thanks very much for adding this.

[gaussmarkov]

hey!  i just passed 1000 posts! 

[suprleed]

Gauss,

I've gone thru your tutorial on the DOD 250 from your website several times and have used LTSpice to analyze the waveforms of both a distortion and boost pedal I've built and modified.  Great stuff.  If I can find a spare minute or two I hope to analyze the impedance of these pedals as described in your tutorial.

Do you know where I can find additional models for the LTSpice library?  Specifically, my next project is a NJM386 based practice amp and I would love to do some spice analysis on it before I start building.  Problem is, I can't find a model of the 386 chip in the component library.  Any suggestions on where to look?  Maybe it's already in there I"m just not looking in the right place...any help would be greatly appreciated.

Great website by the way.  I refer to it often!

Thanks again,
AP

[gaussmarkov]

i'm pleased to hear that stuff has been helpful.  it's pretty amazing what a DIYer can cobble together these days for free on the net.

one excellent source for stuff like this is the LTSpice user group on yahoo.com.  in the files section, there is a lib (library) subdirectory that contains all kinds of useful models, including one for the LM386.  there is a demonstration file as well to show you how to use it.  these were authored by Helmut Sennewald, who has made an enormous contribution to that group with first-rate stuff.

the link to the LM386 files is http://tech.groups.yahoo.com/group/LTspice/files/%20Lib/LM386/  but you will have to join yahoo.com to become a member of a group.  it's not a big deal.

if you run into problems, please post and i'm sure a bunch of us can help.  i'm pretty much a beginner myself but there are others who are quite adept at LTSpice.

all the best, gm

p.s.  i should add that it is fairly easy to insert generic SPICE models and subcircuits into LTSpice, so that the SPICE models in other libraries and those produced by manufacturers (sometimes found in datasheets) can be used as well.  a tutorial on this would probably be a helpful thing to write.   Helmut did this for the IRF510 here.

[suprleed]

Thanks Gauss.  Already ran a few sims on the 386.  Pretty interesting stuff.

I'm still a total greenie on the LTSpice, but it sure is cool!

Rock on!