Joule Thief

[gyulasun]

I don't even use ferrite.  I just coil around a coil.  See my previous posts, page...  oh to hell with it, picture included.

And no one has yet explained to me why electricity would rather flow through the LED rather than the transistor E-C path.  I don't know how this circuit works with regard to this path.  I do know, however, that the higher the resistance, the lower the oscillations of the magnetic flux.

# of turns are inaccurate to the image below.

@jadaro2600
In the meantime I have answered it in your Transistor Discussion thread and I noticed you read it already, now some additions to the above:
The transistor is a controlled switch here,  the 20 kOhm resistor establishes how much current will be able to flow through the collector-emitter path from the battery via the coil.  The higher the resistor at the place of the present 20 kOhm, the higher the C-E resistance path becomes,  hence the smaller the coil current :  ---> so magnetic flux also gets smaller,  your observation is correct.

Re on your removing the resistor path from the base (you must have meant your 20 kOhm resistor in schematics, see your Reply #3294, page 330) you practically removed the DC bias from the base-emitter and you still found the circuit working. 

The explanation is that the base-emitter is able to remain switched on from the pulse voltage coming from your 40 turn coil and base current can flow via your 100 nF capacitor.  This kind of operation is called Class-C when the transistor base bias current comes completely from the input AC signal (in this case the input signal is the peak value of the induced current in the collector coil and in the coupled coil) and no any other DC bias is provided.  This is not a stable operation because at low battery voltages like 1.2 - 1.5V the circuit may not start up at the first switch on like in the case when the small DC bias is present via the 20 kOhm.
So do not be surprised you cannot start your jf without the 20 kOhm,  however once you started it with that resistor present, then you may remove it and the jf continues working in most of the cases whenever the induced and transformed voltage to the B-E is able to open (hence control) the transistor.

rgds,  Gyula

[maw2432]

@ Gadgit   

It looks great and bright too.   Nice picture. 
I bet this will make some kids very happy and excited to see.   

Happy Birthday

Bill

[electricme]

@Gadgetmall


                        HAPPY BIRTHDAY           


                       Many Happy Returns For The Day


A bunch of flickering neons would make a loverly candle replacement
                                     on top of a cake   

General Jim

[electricme]

@Pirate
Bill, I bought two 1Farad 5.5v super caps last monday.
As you are the most experienced on them (I think you are anyway), and I havent any experience with them, what is the best way to use them?
I have both in seperate plastic bags at the moment, tucked away in the parts draws.
Never having used these things, I'm a bit timered.

It's almost midnight here, the old brain is a bit dopy with lack of sleep, I betta have a rest lol.

Had to reset the mouse trap 3 times today, there breeding faster than I can get em.

Jim

[Koen1]

Hi guys,
and HAPPY BIRTHDAY AL

I was just looking around an online store for some components
because I plan to build the MK1/Gadgetmall/Jeanna hybrid ultra low power JT
as in the schematic from this post: http://www.overunity.com/index.php?topic=6123.msg159208#msg159208

I have a few questions that some of you will probably be able to answer... if you don't mind.

The stores I checked do not have HEP638 Germanium pnp transistors, and most don't really sell
any Germanium transistors at all.
What other types of (Germanium or other) transistors could be used instead?
And does that require the use of different components in the rest of the circuit too?
(I can imagine the potmeters might have to be changed too. for example.)

Second question is about the 20K potmeters. A store I visited had an offer on pots,
but only of a specific slide-slot type, not of the turn-knob type or something else,
only those slide things. Also, only in a very low wattage.
Besides the pots having to be 20K in this schematic, what else should I look for
in the pots? Should they be of a certain minimal or maximal wattage, does it matter
if they're freakishly cheap low wattage low quality pots?

My thanks in advance to anyone who can answer some of these questions.

kind regards,
Koen