Joule Thief

[amigo]

@jeanna,

I am sorry, I assumed that everyone here is also reading other threads on this forum, as they all relate to the search for "free energy." One can, and should, never put all eggs into one basket...

Dr.Stiffler's work has been presented here and is still available. I strongly encourage everyone to read the whole thread because it contains valuable information and development time line.

After all you never know where you might get an idea to further your own branch of research, but you will definitely never get any if you do not venture into other areas, that's for sure.

[jeanna]

Thanks amigo,

I am relatively new to electronics and I have had a hard time following his work. I should try again. I have learned so much since the last time I looked at his thread, I may find it easy to follow, and inspiring.

Of course, it seems every time I look up from my own work table, it is 11:30PM again...

Thank you,

jeanna

[jeanna]

Hi everybody,

I checked out the relationship between the
resistance of the transistor base,
frequency and
voltage when in a jtc a little bit more today.

To review, I checked toroids wound as 'a known', and without changing anything about the toroid, I put it into a breadboard with the same individual
2N3904,
1k ohm pot at the base of that transistor

Then on my scope, I checked and recorded both
the voltage and
the frequency coming off the secondary wire of a known description.

Then I changed the value of the resistance at the base of the transistor while watching the voltage and frequency change.

The first one I tested was the "zebra with kynar".
6T,6T,74T

Here are 3 tests on the same "zebra with kynar":

181 kHz
47 V
971 ohms

142 kHz
59 V
262 ohms

33 kHz
79 V
0.6 ohms

Then  I put the "XTree" through the same tests.
11T,11T, ~75T

80 kHz
53 V
971 ohms

38 kHz
91 V
32.5 ohms

Both  of these cores are on the Tor-23 called 'charcoal'.
This is a very small .3 inch ID toroid. I have always liked the results but because it is so small, it just doesn't get the volts. It occurred to me after last night's tests that this may be something that will give me higher frequency . I think it did.

Also, these similar cores have the same number of turns of the secondary, although the materials of the secondary are different the gauge of both secondarys is 30 awg.
However, these are made with different primary turns.
Also, they are not made the MKx way.
They are both made the evil mad scientist way, but one has fewer turns.
The battery is about 1.3v (that is something that unfortunately changes over time.)

So, please, look again and see what you see different about them when I change just the base resistance.

What I see changing is the frequency goes up and the voltage goes down when I raise the base resistance.

Tonight I will use a 20k ohm pot and have more of a look. If I see a turn around at any point I will do more precise tests.

thank you,

jeanna

[xee2]

@ jeanna

I am not sure if you will understand this (because I think it is a bit confusing, not because I think you are not smart), but this is my attempt at explaining why the base resistor changes the frequency. Perhaps you, or someone else, can make the explanation simpler to understand.



THEORY OF JOULE THIEF FREQUENCY VS BASE RESISTOR VALUE  by xee2

Increasing the base resistor value reduces the base current. This current flows through the base coil. When the resistor value is high the current is very small. When the base resistor value is low the base current is larger.

When the transistor turns on the current increases slowly in the collector coil (as a result of the inductance of the coil). The changing current in the collector coil induces a current in the base coil that opposes the base current that is already flowing there due to the base resistor. The larger the current change in the collector coil is, the larger the opposing induced current in the base coil will be.

When the transistor turns on the collector coil current builds up very slowly. At some point the increasing current in the collector coil will be large enough that the opposing induced current in the base  coil will be large enough to cancel the current due to the base resistor and then the transistor will turn off. If the base resistor value is small, then the base current will be large and it will take longer for the opposing base coil current to increases to a large enough value to be big enough to cancel the base current flowing due to the resistor. Thus it takes longer for the transistor to be turned back off when the base current is large (small base resistor value) than when the base current is small (large base resistor value).

The frequency is just how often the transistor is turned on and off. With a small base resistor value (large base current) this happens less often during each second due to the longer time it takes the transistor to be turned back off. Thus increasing base resistor value increases frequency and decreasing base resistor value decreases frequency.

So frequency depends on the base resistor value and the collector coil inductance.

[jeanna]

@Xee2,
Your explanation is very clear and makes plenty of sense to me.

@All,

I want to finish reporting this little series of tests.
I used the XTree and the same transistor and battery etc as before.
Except, I substituted a 50k pot in the base resistor spot.

It had started at 1.3k ohm so in the beginning it
had these results

90 kHz
48.8 v
1.3 kohm
23mA draw *

I turned the pot until the wave I had changed from 1 inside the markers to 2 and stopped,and moved the markers to the exact spot and took the measurements.

142 kHz
29.5 V
10.3 kohms

and continued.
A sudden change occurred on the screen. It may be an anomaly, but the wave form switched from being in one place to suddenly being in another, like moving 180 degrees along. so the up was now down.
I went back and forth. It is repeatable at that spot.
The trace was a very smooth and beautiful sinewave from here on.
At a continuing cost of volts.

181 kHz
26.9 v
12.5 kohms
7.3 mAmps draw *

then

200 kHz
21 v
26.5 kohms

and finally

200 kHz
7 v
48 kohms
1.1 mA draw *

These last 2 are both at 200 kHz but the voltage continued to drop as the base resistance continued to rise, and the wave is just beautiful. a pure sine wave.
I do not think that really matters, or if it does, it comes at a grave price

So, there it is.

jeanna

* EDIT:
I just realized I never mentioned amps draw from the battery once in this whole thing, so I did 3 checks on the XTree with this 50k pot at the base of the transistor and the amps draw on the circuit is

23mA at 1k ohms

7.3mA at 12.6 kohms

1.1mA at 49 k ohms

I will go back and add these numbers in places close to the right spot.