Joule Thief

[TheNOP]

@theNOP,
I did mean divide. That is about the only thing that is clear in my manual. ... I think...

on 1x you are actualy taking measurements through a 1 mega ohms resistor.
on 10x, you are taking measurements through a 9 mega ohms resistor.

the probe is dividing by 10, so, you must multiply your reading by 10 when the probe is set on 10x.

you say the reading at cap is higher then what the scope show.
altho it might be possible, it is usually just a matter of sweep resolutions.
i mean, getting spikes of 735 volts are quite posible, but since they occure very very fast, they might not be visible on the 1ms setting but might show on the 1u or lower.

as for reading DC(not pulsed) with your scope.
since the display is not really high, it is really difficul to see the trace position change.
you can only see the equivalent of 2 divisions for each polarities and can't clearly see dc bias, i think.
so it leave you to rely solely on the digits volts reading.

[jeanna]

theNOP,
You and xee2 know a great deal more than I am ever likely to know about scopes. I may have been wrong when I said x1 and x10 so and so.

I usually have the scope and probe set to x1 with volts per division at about 4 or 8v until the waves go off the screen and I quickly push x10 button on the meter. I don't have anything going at the moment to make sure I am not saying it wrong. The thing is that it is pretty clear at the time, I think anyway, and when I look at the full range that is possible in total volts per division clues and that sort of thing.

Also, right now, what I am doing is taking my attention away from the waves. And, I can't find a good place to measure much.

I still take measurements, but yesterday and today they were in the 1.2v-3.6v range.

I appreciate your help. I actually think I need to talk to the help desk at velleman. This is just another story of the missing manual except they printed one.

thank you and xee2,

jeanna

[resonanceman]

I have  decided  that I  am not  likely to  find   the kinds of  toroids  that I  will need.

I  have been looking into  making  some toroids myself.

I thought  I would post a few things that  might be of interest to  someone here.

On this page  
http://www.lessemf.com/faq-shie.html#Lead-Copper

under

Why can't I just use lead or copper or aluminum foil for magnetic shielding?

There is  a  partial  list of  permeability's  
It is interesting that  Nickel  is  half the permeability  of iron .
Cobalt is not listed  but  I believe it is similar to  Nickel

There  are some interesting  products on this site .
on this  page
http://www.lessemf.com/mag-shld.html
There is a wide range  of  high permeability  products.
Small  strips  of  the  foils or tapes  could   change a  low permeability  toroid into  a much higher  permeability   toroid
I tried  a  toroid made  of  VCR tape .  I did  get  a JT  to run  with it ........but the  flux didn';t seem to travel  around  the  whole  toroid ...I could not  get  a secondary to  work at all .      I am thinking that  a little high  permeability   tape or  ribbon  might  fix  this  problem .

On that page is something I have heard about but not  found  before .
METGLAS® MAGNETIC SHIELDING FILM  
imagine   a  JT made with  about  a pound of this  stuff  

A little  further  down the page ......something that  might  be very handy  
MuMETAL® WIRE
I am planning on  gettins  some of this  later just to test  some theorys  I have  .

I am currently  looking for  a source of  powdered  nickel.    I am thinking it might  be about the right   permeability  to start with ...... from there  I can  add lower permeability  stuff or higher ....depending on the   application .

I am thinking that   raising  the permeability of the  toroid   with a central core that is  high permeability  like  Mu wire is the way to go .

I  hope to test what could be a variable  permeability  toroid .
I am thinking that   the  secondary may need  a different  effective permeability   for best results .
If  a  medium  permeability  toroid was made  by using  a   low permeability  body with  a core made  with something like Mu wire .......  
IF the strands  of Mu wire  were closer to the surface  the effective  permeability of that  area  would go up .
This  effect might  be easiest to do  with one of the  high  permeability foils.
If  a banana shaped  core was made then wrapped with  foil ...... and the  ends  twisted  as  thin as  possible ..... if the  ends  were  connected  and  then the whole thing   inserted into a mold and filled   with a  low  permeability mix .....   it should  make a toroid   with  2 very  different  permeability's   ( assuming the foil  is thick enough to  carry the flux all the way around the  toroid )


gary  

[nievesoliveras]

@all

I have been surviving lately and could not be as usual. But here I am again and with a question to @mk1 or anyone that can answer it.

How do i check the resistance used by the pot on the circuit?

Jesus

[electricme]

@Mk1,
I took a look at this video on U Tube, wasnt this amazing, as the magnet was applied, the motor slowed and the AMPs went up
I gess this relates to the effect we see as a battery discharges, as the voltage gets lower and lower, the Amps go up to compensate for less voltage.

Reversed the Magnet and the AMPs fell and the motor speed up.
Here we see the oppersate, the same effect can be seen if the voltage is rased over the supplied battery voltage, ie: 12v batt add 1 wet cell =14v, the Amps go down as the "over volts" are above what is required to drive the dc motor.

I used to see special batteries made for the oldre VW beetles, they had a 6v system, when the extra cell was added, the lights improoved to no end, the starter motor worked real good, just had to tweak the generator to give a little more output.

Now, what would happen it the iron laminations which this transformer was wound with were "Pre magnetised" that would be interresting, if the iron was magnetised the wrong way, the output would always struggle, if magnetised the other way, the output would be "always enhansed".

jim

Good find this one.