Re: Terry's DRSSTC - Frequency/Pulse Width Controller

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Sparktron01@xxxxxxxxxxx 

Terry

You could use a 78xx or 317 3 term voltage regulator as an active current 
source into a capacitor to make a linear sawtooth wave, then adjust pulse 
width with a comparator, pulse width would then be linear (with a linear 
pot position).  I believe such a circuit could be simply built using a 555 
+ a 3 term VR.


Best Regards
Dave Sharpe, TCBOR/HEAS
Chesterfield, VA USA


> Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>
>
> Hi All,
>
> For my DRSSTC, I was going to have two knobs.  A 100k single turn pot in
> series with a 1k resistor to do the pulse width and basically act as a
> power controller following Steve's suggestion.  And another pot set up just
> like it (maybe a ten turn) for the pulse width.  The "linear" pulse width
> thing is easy with a LMC555 timer.
>
> However, most LMC555 circuits and their types are  "F : 1/R"  type circuits
> so the frequency control is not at all linear.  I was thinking zero on the
> pot would be like 1Hz, 25% on the pot 250Hz, 50% on the post 500Hz, 100% on
> the pot 1000 Hz...
>
> I just wanted to check to see if anyone and an easy simple way to do
> that?  I checked around for ICs and such, but did not find any wonderful
> solutions.  I can probably do it with a few simple digital chips, but
> thought I would ask...
>
> I am going for primary current trip and IGBT temperature
> protection...  Still trying to figure out how to "saw up" the box...  I did
> get one heck of a terminal block milled out for the output ;-)  IGBT cross
> conduction will be "controlled" buy a 1/4 inch thick sheet of lexan :o))
>
> All is going well, but I "had" to buy a bunch of power tools for the
> project too :o)))  Also worked on the tube coil and replaced the grid
> resistors with TO-220 types from Digikey and a real heat sink now so the
> coil would not smell like burning wood...  Getting ready for Gerry and I's
> "show" on the 29th...
>
>
> In a brilliant leap in cybersquatting, guess who
> grabbed  www.drsstc.com  :0)))  Nothing there this moment but the jump
> pages, but I hope to put all my DRSSTC stuff there and link all the other
> cool DRSSTC sites.  I hope to avoid the "void" with my OLTC thing...  That
> server can also host other DRSSTC sites under it since it is a full high
> powered server thing with individual sites and E-mail and all...   If
> anyone has any ideas for the site or you want to put your DRSSTC stuff
> there (DRSSTC stuff ONLY though) let me know at:
>
> terry-drsstc(put an asterisk thing here)drsstc.com
>
> I have a big list of folk's sites to get linked up already.  I am even
> using real web publishing software now, but I have found that is it "me"
> not the "software" :o))  So no "flashy stuff" still :-))))
>
>
> BTW - Rather than being on the "bleeding edge" of this DRSSTC stuff I am
> now "following" :o)))  It's sort of nice :-)))  Many thank to those that
> figured the hard stuff out!!!  I really think the DRSSTC will change
> "everything" in our hobby!!!
>
> Cheers,
>
> 	Terry
>
>