Joule Thief 101

[tinman]

<<< as can be seen in my video,there are many circuits that operate just as well as a !MH! joule thief circuit. >>>

Facepalm.

In an ironic, but not surprising twist, all that you are doing is proving my point.

Your SSG circuit IS a blocking oscillator.  So it is a variation on a Joule Thief.  From what I could see in the clip, it is self-clocking so it's basically a Joule Thief that you are showing in your clip.

I know that you are not going to provide a schematic, who needs pesky details like that...

No MH,the facepalm is on you im afraid.
Like i said right from the word go-these circuits are not variations of a joule thief circuit--they are joule thief circuit's. When will you get it through your head that a joule thief is not one single circuit,but many that can perform the operation of draining a battery down to very low voltage,while putting out higher voltages required to run the required load--in this case,an LED.

If you do not know what the simple SS SSG circuit is,and require a schematic,then you really need to do some home work.
Should i place a capacitor some where on that circuit,just so as you are happy that you can visualize a capacitor ?. Or should i make an individual !!MH approved!! RLC circuit ?

But to save you some trouble of doing a bit of your own research MH,the circuit i used is below. You may place the LED in either position,as it will work quite fine in either.

So is it a blocking oscillator MH,or a flyback driven transformer?. Dose the transistor switch on hard while the magnetic field is building around the inductor,or dose the transistor switch on when the field is collapsing around the inductor?.


Brad

[tinman]

Brad:


Quote from BigClive: "There are a few variants on the design which add extra components to improve efficiency, but a true Joule Thief uses a single transistor, 1K resistor, hand wound ferrite bead transformer and the LED you want to light."


You forgot to use BigClive's definitions of the JT circuit.  He is the one that came up with that name in the first place so, I think he gets to decide what it is, and is not. 


Of course, according to BigClive's definitions, a lot of my circuits are not JT's.  Maybe we here should come up with our own name to describe a blocking oscillator/feedback type circuit that boosts voltage and runs down batteries? 


I used the name "Joule Pirate"  on several of my circuits as Pirates have been known to steal stuff, ha ha.  I am not saying we need to use that but, all of my Fuji type circuits are not really JT's using Clive's definition.  They need to be called something.


Bill

If i remove the pot,and replace that pot with a resistor,i then have what big Clive states
A resistor,transistor,ferrite bead/toroid,and an LED-see circuit above in my last post.

Brad

[MileHigh]

Brad:

You were basically showing a variation on a Joule Thief/blocking oscilator and not really a different type of circuit architecture like you were alluding to so you get the facepalm.  I am pleasantly shocked that you provided a schematic after the fact.  Why don't you do that for all future clips in the actual clip where you demonstrate the circuit?

When will you get it through your head that a joule thief is not one single circuit

Get it through your head that circuits have different architectures and we often will refer to a certain architectural class of circuits with a common name and other circuits in a different architectural class with another different common name.  Undertake to learn something new instead of being so stubborn and holding your breath until you turn blue.

If you do not know what the simple SS SSG circuit is,and require a schematic,then you really need to do some home work.

Bullshit, the minimum experimenters should expect is to at least get a schematic.  Go look at some of your clips that are three years old so you can't remember the circuit anymore and watch yourself do a three minute rundown of where all the alligator clips are connected and see how it feels.

RLC circuit ?

Hey George Orwell, what happened to the Joule Thief as an RLC circuit?

MileHigh

[tinman]

Brad:


Get it through your head that circuits have different architectures and we often will refer to a certain architectural class of circuits with a common name and other circuits in a different architectural class with another different common name.  Undertake to learn something new instead of being so stubborn and holding your breath until you turn blue.

Bullshit, the minimum experimenters should expect is to at least get a schematic.  Go look at some of your clips that are three years old so you can't remember the circuit anymore and watch yourself do a three minute rundown of where all the alligator clips are connected and see how it feels.



MileHigh

You were basically showing a variation on a Joule Thief/blocking oscilator and not really a different type of circuit architecture like you were alluding to so you get the facepalm.

Oh really.

I am pleasantly shocked that you provided a schematic after the fact.  Why don't you do that for all future clips in the actual clip where you demonstrate the circuit?

Because it is painfully clear even when i do,you still pay no attention to it.
Here is your description on how the !your! JT circuit works.

How a Joule Thief works:

This circuit used in this project is a modified "Joule Thief." A Joule Thief is a self-oscillating voltage booster. It takes a steady low voltage signal and converts it into a series of high frequency pulses at a higher voltage. Here is how a basic Joule Thief works, step by step:
    1. Initially the transistor is off.
    2. A small amount of electricity goes through the resistor and the first coil to the base of the transistor. This partially opens up the collector-emitter channel. Electricity is now able to travel through the second coil and through the collector-emitter channel of the transistor.
    3. The increasing amount of electricity through the second coil generates a magnetic field that induces a greater amount of electricity in the first coil.
    4. The induced electricity in the first coil goes into the base of the transistor and opens up the collector-emitter channel even more. This lets even more electricity travel through the second coil and through the collector-emitter channel of the transistor.
    5. Steps 3 and 4 repeat in a feedback loop until the base of the transistor is saturated and the collector-emitter channel is fully open. The electricity traveling through the second coil and through the transistor are now at a maximum. There is a lot of energy built up in the magnetic field of the second coil.
    6. Since the electricity in the second coil is no longer increasing, it stops inducing electricity in the first coil. This causes less electricity to go into the base of the transistor.
    7. With less electricity going into the base of the transistor, the collector-emitter channel begins to close. This allows less electricity to travel through the second coil.
    8. A drop in the amount of electricity in the second coil induces a negative amount of electricity in the first coil. This causes even less electricity to go into the base of the transistor.
    9. Steps 7 and 8 repeat in a feedback loop until there is almost no electricity going through the transistor.
    10. Part of the energy that was stored in the magnetic field of the second coil has drained out. However there is still a lot of energy stored up. This energy needs to go somewhere. This causes the voltage at the output of the coil to spike.
    11. The built up electricity can't go through the transistor, so it has to go through the load (usually an LED). The voltage at the output of the coil builds up until it reaches a voltage where is can go through the load and be dissipated.
    12. The built up energy goes through the load in a big spike. Once the energy is dissipated, the circuit is effectively reset and starts the whole process all over again. In a typical Joule Thief circuit this process happens 50,000 times per second.

So now i ask you once again MH--how dose the circuit i posted work?

Hey George Orwell, what happened to the Joule Thief as an RLC circuit?

Hey Wile E Coyote,looking at your description of the workings of your JT circuit,  12-The built up energy goes through the load in a big spike. Once the energy is dissipated, the circuit is effectively reset and starts the whole process all over again,how exactly dose the transistor switch on once the battery voltage go's below the switch on threshold voltage of the transistor ?. I mean ,it wouldnt have anything to do with junction capacitance within the transistor it self--would it MH,as that would mean that the!your! JT circuit would be an RLC circuit-->and we cant have that.

Your description is flawed,and as described,your JT circuit would stop operating once the battery voltage dropped below the threshold voltage required to switch on the transistor. In my circuit(provided),i use a 2n3055 transistor,and that requires 700mV at the base to switch on the transistor,and yet (as seen on the video)my circuit is quite happy to run on only 250mV.
So following your description of the workings of your JT MH,how exactly would it continue to run once the battery voltage is below the required voltage to switch on the transistor ?.
Facepalm ?

Below is your JT circuit,along with the circuit i used. Now have a good look MH,and tell me the difference in operation between the two.


Brad

[tinman]

I would also like to add that in my circuit below,it is better to have the LED in position 2. This creates a current loop through the LED and inductor only,while position 1 creates a current loop that includes the battery,where the voltage potential through the loop is opposite to that of the batteries voltage potential.


Brad