Re: good scopes for coiling

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Paul B. Brodie" <pbbrodie@xxxxxxxxxxxxx>

Malcolm,
Thanks for trying to help me and I apologize but I haven't got a clue as to 
what you are trying to convey with your ASCII drawing. I'm pretty sure that 
you are right about needing a shunt for my meter though.

I have been studying the LM555 data sheet to try and get some idea of how 
this Tesla Coil Tuner (TCT) circuit works because it is different from any 
other 555 circuit I have ever seen. According to the schematic that came 
with the TCT, it is different from all of the examples included with the 
data sheet. I'm having a lot of trouble figuring out how it functions and 
why it didn't just use the astable multivibrator configuration. One thing 
that really has me confused is that there is no connection to the discharge 
pin #7 and no power to pin #6. I did note in Terry's documentation that it 
has a square wave, 50% duty cycle output. Also, mine is evidently working 
because the LED lights when I turn it on and stays lit throughout the range 
of the pot. If this is the output, and Terry tells me it is between 0 and 9 
volts, 5 mA or less, isn't this pulsed DC??? Let's say it is putting out a 
100kHz 9 volt signal at 50% duty cycle, what should I read on the meter set 
for DC volts? I think I have totally confused myself and my DVM decided to 
go on the Fritz (oops Terry, sorry for using your name in vain)! I was at 
least hoping to use it to measure the frequency the TCT is putting out. I 
did find my old el cheapo DVM, so I can at least measure milliamps, 
millivolts, and volts.

I know that this is a mighty tough task but if you can straighten me out 
just a little bit, I will be eternally in your debt!!! I'm really sorry for 
being so obtuse. I hate to be a burden. Thanks.
Paul
Somehow Continuing to Think Positive

----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Thursday, May 19, 2005 7:19 PM
Subject: Re: good scopes for coiling

Original poster: "Malcolm Watts" <m.j.watts@xxxxxxxxxxxx>

Hi Paul,

On 18 May 2005, at 22:55, Tesla list wrote:

 > Original poster: "Paul B. Brodie" <pbbrodie@xxxxxxxxxxxxx>
 >
 > Malcolm,
 > Yes, my intent is to rectify the AC output and feed it to the meter.
 > One problem is that I don't have any idea what the output voltage is
 > and whether or not I might get dropouts, if the level drops lower than
 > the forward voltage drop of the diode(s). I am assuming that since the
 > output has to drive the LED, it is high enough.
 >
 > My problem is that trying to judge the output level by the relative
 > brightness of the bipolar LED is not a very good option for me because
 > of my extremely poor vision. I'm not sure that I will be able to do
 > this at all. I was hoping that I could use a very simple rectification
 > because I'm not looking for any particular accuracy. I just want to
 > use the meter to indicate the signal strength as it fluctuates so that
 > I can find the maximum point. If this is all I am doing, can I just
 > use a Schottky diode as a half-wave rectifier and feed this to the
 > meter? The problem here is I will compound any problem I might have
 > with a low signal level, cutting it in half with the rectifier. I
 > think what I'll do now is just start trying things. I have nearly
 > completed the tuner itself. I only need to solder the connections to
 > the LED and I'm through. I will try the half wave rectification with a
 > Schottky diode first and see what I get and go from there. Thanks.
 > Paul Think Positive

You should easily get enough current to drive a 50uA FSD meter. Try:

            |\ |
       +----| \|-----------------+
       |    |/ |       || C      |
       |           +---||--------+
  -----+    | /|   |   ||        +--------------
       +----|/ |---+-----o     o-+
            | \|         -     +
                           meter

You may need to connect a shunt across the meter.

Malcolm


 > ----- Original Message -----
 > From: "Tesla list" <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx>
 > To: <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx>
 > Sent: Wednesday, May 18, 2005 6:56 PM
 > Subject: Re: good scopes for coiling
 >
 > Original poster: "Malcolm Watts"
 > <<mailto:m.j.watts@xxxxxxxxxxxx>m.j.watts@xxxxxxxxxxxx>
 >
 > On 18 May 2005, at 9:58, Tesla list wrote:
 >
 >   > Original poster: "Paul B. Brodie"
 > <<mailto:pbbrodie@xxxxxxxxxxxxx>pbbrodie@xxxxxxxxxxxxx>
 >   >
 >   > Hi,
 >   > Terry has the plans for the Tesla Coil Tuner that I think
 >   basically > does what Malcolm has described here. Karl Lindheimer
 >   posted a note > earlier about using the TCT with the URL. I will
 >   repeat it. The > schematic and directions are located here: > >
 > <http://hot-streamer.com/TeslaCoils/Misc/TCT/TCT.htm>http://hot-stream
 > er.com/TeslaCoils/Misc/TCT/TCT.htm
 >   >
 >   > It is a 555 oscillator with a bi-directional LED. I downloaded the
 >   > plans and directions and just happen to have all of the parts in
 >   my > junk bin, except for the 10K audio taper pot with switch. I
 >   plan to > get one of these at Radio Shack tomorrow. One thing I was
 >   > contemplating doing differently is use a micro-ammeter I have on
 >   hand > instead of the LED. Won't this give a better indication in
 >   place of > trying to judge the brightness of an LED?? Is this so, or
 >   am I missing > something? Maybe I can use the LED and the meter?
 >   What do you think? > If I keep getting sidetracked with these
 >   projects, I'll never complete > my TC! ô¿ô Paul Think Positive
 >
 > I assume you will have some form of HF rectification to drive the
 > meter?
 >
 > Malcolm
 >
 >   > ----- Original Message -----
 >   > From: "Tesla list" <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx> >
 >   To: <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx> > Sent: Tuesday, May
 >   17, 2005 6:43 PM > Subject: Re: good scopes for coiling > > Original
 >   poster: "Malcolm Watts"
 > <<mailto:m.j.watts@xxxxxxxxxxxx>m.j.watts@xxxxxxxxxxxx>
 >   >
 >   > On 17 May 2005, at 11:45, Tesla list wrote:
 >   >
 >   >   > Original poster: "Mercurus2000"
 > <<mailto:mercurus2000@xxxxxxx>mercurus2000@xxxxxxx>
 >   >   >
 >   >   > So there is no electronic way of measuring the resonance of a
 >   > >   secondary without complicated or expensive electronics? -----
 >   >   Original > Message ----- From: "Tesla list"
 > <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx> To: >
 >   >   <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx> Sent: Sunday, May
 >   15,
 > 2005 3:59 PM Subject: Re: >
 >   >   good scopes for coiling
 >   >
 >   > I'm sure a way can be devised that doesn't require use of an
 >   > oscilloscope and sniffer probe although that is probably the best
 >   > option. Connecting a signal generator which can supply some
 >   current (a > buffered 555 e.g.) to the secondary base in series with
 >   a resistor > would allow monitoring of current through the resistor
 >   with a LED in > parallel by sensing the voltage across it. That will
 >   interfere to a > far lesser degree with correct operation of the
 >   secondary. I see no > reason why it shouldn't work although you can
 >   probably expect several > lesser peaks besides the fundamental. In
 >   my experience, monitoring > base current and finding the peak
 >   doesn't coincide exactly with > maximum Vs although it gets close. >
 >   > Malcolm > >   > Original poster: "Malcolm Watts"
 > <<mailto:m.j.watts@xxxxxxxxxxxx>m.j.watts@xxxxxxxxxxxx>
 >   >   >
 >   >   > On 13 May 2005, at 23:02, Tesla list wrote:
 >   >   >
 >   >   >   > Original poster: "Mercurus2000"
 > <<mailto:mercurus2000@xxxxxxx>mercurus2000@xxxxxxx>
 >   >   >   >
 >   >   >   > Couldn't you take like you said a 555 timer, connect the >
 >     pulsing > >   squarewave output to a TC secondary, then connect a
 >   >   diode to the > >   topload and connect a digital voltmeter to
 >   the >   diode and get a idea >   of > the resonant frequency? Adam
 >   ----- >   Original Message ----- From: >   "Tesla > list"
 > <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx>
 >   >   To: <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx> Sent: >
 >   Friday, May
 > 13, > 2005 10:49 AM
 >   >   Subject: Re: good scopes for coiling > > In a word, no, not if
 >   you >   are after accuracy. Anything you connect > directly to the
 >   secondary >   is going to boost its puny capacitance out > of sight.
 >   > > Malcolm > >   >   > >   > Original poster: Karl Lindheimer
 > <<mailto:karl@xxxxxxxxxxxxxxx>karl@xxxxxxxxxxxxxxx>
 >   >   >   > >   > Hi Keith, >   > >   > A scope and/or frequency
 >   generator >   can be quite helpful in Tesla >   Coil > duty, and for
 >   just about >   any other project that will come >   along. > Since I
 >   am on a low >   "fixed budget" as it were, I built a >   555 timer >
 >   waveform >   generator for about $8.00 total.  I used an >
 >   inexpensive > >   multi-meter for several years before snagging a >
 >    Tektronics 265B >   scope > for under $100 on Ebay.  This scope is
 >   the >   best addition >   to my test > bench in many years, and
 >   continues to >   impress.  My >   Tek scope is rugged > and parts
 >   are still obtainable >   from junked >   scopes. > > Hope that the
 >   above helps, > > Karl > > On >   May 12, >   2005, at 10:32 PM,
 >   Tesla list wrote: > >  >Original poster: > >   "keith"
 > <<mailto:keith.cc@xxxxxxxxxxx>keith.cc@xxxxxxxxxxx> >  > >  >I'm
 > looking to buy a scope >
 >   >     and/or frequency generator for coiling >  and >general use,
 >   but I >   >   don't really have any idea about >
 >   manufacturers/models >etc ­ >   what >   are some good ones to look
 >   for? I've >  read that the older >   tube >   >scopes are better
 >   than modern solid state >  ones for the >   stressful >
 >   >environments generally encountered in high >  voltage >   work, and
 >   >   given that >I'm still new to coiling/hv devices, > >   something
 >   that >   has a good chance of >surviving a few careless > >
 >   errors/poorly >   designed experiments would be good. >Relatively >
 >    low >  cost would >   also be nice. Thanks. > >Keith C > > > > > >
 >   > > >
 >
 >
 >
 >