Re: [TCML] Re: Dummy load for optimum cap size Experimentation

[jhowson4@xxxxxxxxxxx]

If you are at all interested, 
A few weeks ago i pulled what i now believe to be an infrared photo cell out of my colleges trash...i originally thought it might have been an IR laser tube which is why i pulled it in the first place. having no need for the photocell and asociated electronics i discardedthem but i kept the the tube that it was housed in and a nice coated infrared lens. it looks like it was designed to take a wide area of light and focus it onto the photo cell less than an inch away from the interior side of the lens. 
Apparently i am missing the back plate to the tube but that would not be very hard to just remake out of cardboard or something. the holes that were used to attach it might also make a good means of attaching the tube to something for repeatable measurement proposes. 

its yours if you want it... 
4.95 for USPS small flat rate box..unless that price changed.... 
email me off list 
jhowson4@xxxxxxxxxxx 

Thanks, 
John "Jay" Howson IV 

----- Original Message ----- 
From: "bartb" <bartb@xxxxxxxxxxxxxxxx> 
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx> 
Sent: Sunday, August 8, 2010 3:36:19 PM 
Subject: Re: [TCML] Re: Dummy load for optimum cap size Experimentation 

Hi Gary, 

Focusing on photocell: 

What type of photocell are you using? Is it one of those 1/2" circular 
photocells (zigzag line things)? I used something a bit different but 
cheap. Think I got it at Jameco years ago, but this is what I used along 
with the box and description mentioned previously. 
http://www.flickr.com/photos/bart-coils/4872360015/ 

One thing I did have to do was to cover most of the area with black tape 
to remove ambient light as well as force only a portion of the cells to 
react through the hole within the box that the 500W halogens were 
inside. I believe I also had to use minor lens filter (most anything 
will do) between cell and the light coming out of the hole. 

I'd be more than happy to send this to you if you like (no charge and 
don't even want it back). Just send address my way if you want to give 
it a try. 

Best regards, 
Bart 


Gary Lau wrote: 
> OK, back from vacation, time to start the experiments! Igor??? 
> 
> I tried monitoring the lamp brightness using a photocell. Previously I just 
> applied Variac'ed AC to the bulbs to test the photocell response. Today I 
> hooked up the actual spark gap and capacitor to an NST. Just as I feared, 
> the chaotic gap behavior resulted in extremely erratic resistance readings. 
> Useless. I tried placing a big cap across the photocell terminals, but that 
> didn't work. Back to monitoring the bulb temperature with a thermocouple. 
> 
> 
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