Re: Terry's Tesla Coil Tuner

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

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

Hi Mike,

I hooked up the ARB and ran the 100kHz to 600kHz spectrum to check out the
square wave/harmonics thing.  As it turns out it is pretty cool!  the following
is the spectrum with just a resistor in the circuit which clearly shows the
square wave harmonics:

http://hot-streamer-dot-com/temp/TCTs1.jpg

Next is the same spectrum with the bi-color led.  As it turns out, the LED
seems to remove the harmonics!  Probably because they cannot overcome the turn
on voltage of the LEDs

http://hot-streamer-dot-com/temp/TCTs2.jpg

One problem is that the stray capacitance in the timing circuit makes the
"calibration" thing worthless.  It has to be calibrated against a frequency
counter as it turns out.  Many DVMs have a frequency function too.  Since I
cannot control how the circuit is built, there is no way to come up with an
easy fixed calibration scheme.  I will probably offer a $5 calibration
"service" to those that don't have access to a frequency counter.  I am already
going to send people the 1.8nF cap for free since it is easy to mail (small).

I still need to clean the plans up a lot before this is ready for prime time. 
Many thanks to all who have given their thoughs on this!

Cheers,

        Terry



At 11:39 AM 2/9/2001 +0000, you wrote:
>On Thu, 08 Feb 2001 07:55:53 -0700, you wrote:
snip..
>One problem I've found with using square waves for tuning is that you
>can get strong responses at harmonics. 
>
>Have you tried using a single-colour LED in series with the 555's
>supply? (maybe with a parallel resistor) 
>
>