Hello Gene, and thanks for your answer. I have the circuit in PDF format, would you like me to send it to you so you can see it?
2013/2/10 Gene Heskett <ghesk...@wdtv.com> > On Sunday 10 February 2013 19:01:08 Leonardo Marsaglia did opine: > Message additions Copyright Sunday 10 February 2013 by Gene Heskett > > > Hello Andy. > > > > http://imagebin.org/246204 > > > > Here's a picture of what I scoped the other day, this is the signal > > coming out from the IC's that we use to fire the igbt's, as you can see > > those spikes are a little dangerous I think. > > First, I am a CET, and a retired (mostly) broadcast engineer. > > 2nd, Correct, both the spikes, and all that racket on the falling edge > bothers me, a lot. > > First on the overvolt spikes, I'd make sure the scope ground is floating so > that you can attach it to the circuits common. They may not be near as > pronounced if a ground loop is eliminated. > > 2nd, that double or triple shuffle on the falling edge isn't at all good. > Its needless switching and heating in the transistors./ > > Perhaps the grounding and supply bypassing are both suspect. I'd check to > see what effect a .1 paper/mylar capacitor across the buses might indicate > poor bypassing. > > Do you have a URL to that circuit? I'll take a look at it if I can. > > > I've talking a lot with Tim and he's a great help, he's always helping > > me with his advices and knowledge. > > > > About using an arduino or fpga, I've been thinking about that too, I > > need to catch on with VHDL since I've only made some simple counters > > and multiplexers but I really like the idea of make a whole system from > > an fpga. > > > > Anyway, the main problem here is after the firing IC's since the > > oscilator is generating a perfect square wave form. > > > > > > 2013/2/10 andy pugh <bodge...@gmail.com> > > > > > On 10 February 2013 22:15, Leonardo Marsaglia > > > > > > <leonardomarsagli...@gmail.com> wrote: > > > > based on DIY circuits found on the internet. > > > > > > I guess you have seen: > > > http://webpages.charter.net/dawill/tmoranwms/Elec_IndHeat1.html > > > (Lots of clever stuff, much better done in software now) > > > > > > > Anyway, the real deal here is always how to have a clean square > > > > signal to fire the igbt's. > > > > > > Sounds like a job for Arduino or FPGA. I can't help feeling that there > > > ought to be a suitable Mesa module, but Arduino's have PWMs that share > > > a clock, so for suitable thresholds are guaranteed not to overlap. I > > > don't know how smoothly you can change frequency > > > > > > -- > > > atp > > > If you can't fix it, you don't own it. > > > http://www.ifixit.com/Manifesto > > > > > > > > > ---------------------------------------------------------------------- > > > -------- Free Next-Gen Firewall Hardware Offer > > > Buy your Sophos next-gen firewall before the end March 2013 > > > and get the hardware for free! Learn more. > > > http://p.sf.net/sfu/sophos-d2d-feb > > > _______________________________________________ > > > Emc-users mailing list > > > Emc-users@lists.sourceforge.net > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > Cheers, Gene > -- > "There are four boxes to be used in defense of liberty: > soap, ballot, jury, and ammo. Please use in that order." > -Ed Howdershelt (Author) > My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! > My views > <http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml> > It matters not whether you win or lose; what matters is whether I I win or > lose. > -- Darrin Weinberg > I was taught to respect my elders, but its getting > harder and harder to find any... > > > ------------------------------------------------------------------------------ > Free Next-Gen Firewall Hardware Offer > Buy your Sophos next-gen firewall before the end March 2013 > and get the hardware for free! Learn more. > http://p.sf.net/sfu/sophos-d2d-feb > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- *Leonardo Marsaglia*. ------------------------------------------------------------------------------ Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
