OLTC update

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi All,

Today I worked on the control box that controls the IGBT array:

http://hot-streamer-dot-com/temp/OLTC-PowerContFront.jpg

http://hot-streamer-dot-com/temp/OLTC-PowerContBack.jpg

http://hot-streamer-dot-com/temp/OLTC-PowerContIn.jpg

It still needs the current transformer and LM311 circuit, but I tested the
LMC555 timer part.

http://hot-streamer-dot-com/temp/OLTC8-11-01.gif

The schematic is at:

http://hot-streamer-dot-com/temp/OLTC-TimingControl.gif

I changed the 50K pot to a 100K 10 turn pot and put a counting dial on it.
I also put a 100nF cap in series with the 10nF cap to get 9.90nF.  Since
the pulse width = 1.1RC, this makes the dial count off directly in uS.  So
it is very easy to just set the dwell time with this dial.  I hope it won't
be needed other than for testing.  The pot and dial run about $40!

I was very surprised at how accurate the dial was!

Dial setting	Pulse width(uS)
40		39.81
50		49.67
60		59.55
70		69.54
80		79.52
90		89.49
100		99.99
120		119.8
130		129.8
140		139.8
150		149.4
200		200.1
400		401.5
600		603.0
800		802.6
1000		999.4

It weighs in at 1 lb. 5 Oz. mostly the heavy aluminum box that should
protect it a bit from streamers.

Mostly waiting for parts to come tomorrow...

Cheers,

	Terry