Joule Thief 101

[tinman]

Here is the simple SS SSG circuit being used as a joule thief circuit.
As you can see,no problem at all driving a 10mm LED quite brightly at .25v(250mV)

So be wary of those here that quote things like-->No, they are not Joule Thief circuits because it looks almost certain that they will not have the same performance as a Joule Thief when it comes to extracting energy from a nearly dead battery that has a low voltage-high impedance output.

Or-->So it's not a Joule Thief because it does not do anything special to extract energy from a very-low-voltage battery.


Or-->they will not have the same performance as a Joule Thief when it comes to extracting energy from a nearly dead battery."

Comments like this are untrue,and as can be seen in my video,there are many circuits that operate just as well as a !MH! joule thief circuit. The one pictured in the video (the simple SS SSG circuit)is now running on a battery with a voltage of only .14v--even with the large 2n3055 transistor--you dont get much better than that.

Next we will be building a mechanical JT,and im hoping that it will operate near the .1v area.

https://www.youtube.com/watch?v=1f1DG4syHCw

Brad

[Nink]

Anyone know if a JT is a good solution for charging a NiCad battery from a low voltage trickle source.  I need to include JT in a circuit to run LEDs but I figured if I could use the same circuit for both
1) When turned off Tickle Power Source => JT => charges Nicad
2) When turned on uses Nicad => JT=> LED

If this is the case what would be the best JT circuit to use. Low voltage Low amp power source <1v DC  ~5 to 20mA   

[MileHigh]

So the JT is not one single circuit,but can be many types of circuits that perform the same operation -->and that is to drain the last remaining energy from a nearly depleted battery.

What's language if we don't use it properly?  You want to be an effective communicator and this doubly applies to electronics where you want to use the right concepts, and use the correct nomenclature so as to avoid confusion.  If you don't do that then you can lose Mars satellites because someone was too lazy to say they were using metric units instead of English units.

A Joule Thief is a pulse circuit that is a type of blocking oscillator.  There can indeed be variations on Joule Thief designs but they are all types of blocking oscillators.  Feedback oscillators based on some kind of RLC circuit on the other hand are not pulse circuits at all.

Both Joule Thief/blocking oscillators and feedback oscillators can drain a battery no doubt.  For both types of designs there will be a minimum battery voltage where they can self-start.  Chances are that Joule Thief designs can self-start at lower voltages than feedback oscillators.  Then for both Joule Thiefs and feedback oscillators if they start at a higher voltage and run continuously they can keep on running lower than the minimum self-start voltage and keep on running to some minimum operating voltage.  As long as the oscillation takes place the circuit can stay alive.

So a feedback oscillator can drain a battery to a quite low voltage also as long as you don't stop it from oscillating, but it is not a Joule Thief.

Now, is that such a hard concept to understand?  I don't think it is.

For both designs, by carefully choosing the configuration and the component values you might be able to get self-starting going at a quite low voltage and sustained oscillation down to an even lower voltage.

Different Joule Thief designs are like variations on Romance languages, like comparing Spanish to French.  A feedback oscillator is a totally different beast, like comparing it to Mandarin Chinese.

MileHigh

[MileHigh]

Here is the simple SS SSG circuit being used as a joule thief circuit.
As you can see,no problem at all driving a 10mm LED quite brightly at .25v(250mV)

So be wary of those here that quote things like-->No, they are not Joule Thief circuits because it looks almost certain that they will not have the same performance as a Joule Thief when it comes to extracting energy from a nearly dead battery that has a low voltage-high impedance output.

Or-->So it's not a Joule Thief because it does not do anything special to extract energy from a very-low-voltage battery.


Or-->they will not have the same performance as a Joule Thief when it comes to extracting energy from a nearly dead battery."

Comments like this are untrue,and as can be seen in my video,there are many circuits that operate just as well as a !MH! joule thief circuit. The one pictured in the video (the simple SS SSG circuit)is now running on a battery with a voltage of only .14v--even with the large 2n3055 transistor--you dont get much better than that.

Next we will be building a mechanical JT,and im hoping that it will operate near the .1v area.

https://www.youtube.com/watch?v=1f1DG4syHCw

Brad

<<< 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...

[Pirate88179]

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