Joule Ringer!

[poynt99]

poynt99

This was posted quite a while ago
It is in my opinion the best description  of how a JT works that I have seen.

Yes, I think I saw that description quite some time ago here.

It is exactly the notion I started with when I began looking at the wave forms in detail in my simulation, and I believe this is most likely the true "turn off" mechanism involved. It is difficult to "see" all this happening as it all happens simultaneously, so one has to extrapolate what they know into what they see, and I think xee2 has done a good job of that.

The JT is one of only a few transistor circuits that operates in all four possible bias modes throughout it's cycle; forward-active, cutoff, saturation, and reverse-active. I was looking at the "saturation" mode as a possible turn-off mechanism, because appreciable current may flow in the collector, even though Vce may be quite small, smaller than Vcesat.

Anyway, I'll look at the simulation again when I have time and see if I can prove it all out, one way or the other.

Thanks,
.99

[poynt99]

The main thing about the JT circuit that has bothered me from the start is that a lot of EE's kept claiming that this is well known and there is nothing new here.  OK, fine.  Then why can I rebuild a simple LED flashlight that took 3 AA's and run it on a "dead" AA that make the light brighter and last much longer than with the 3 AA's?

It's quite simple really. A "dead" battery may have little voltage available at its terminals, but it still contains energy and current can still be drawn from it by shorting it out. The JT shorts out the battery through the collector coil and draws current. When the transistor turns off, the inductive kickback manifests as a high voltage spike which is much higher in amplitude than is required to turn on the LED.

So in effect, the JT is a converter of sorts; it converts a current (which we can still extract from the dead battery) into a high voltage, which is able to forward bias a LED or string of LEDs.

Does that make sense?

Bill, have you ever installed a high power audio amplifier in your vehicle? It works on a similar principle, but the goal there is to increase the power amplification beyond what can be achieved using only the 12VDC available from the vehicle battery. A large part of the after-market power amplifier is the power supply; it converts (i.e. raises the voltage) 12VDC to perhaps +/- 35V or so, similar to what your home theatre amplifier might use.

.99

[Omnibus]

@poynt99,

This seems somewhat connected to the topic at hand -- would you be interested in making a PSpice simulation of this schematic: http://www.overunity.com/index.php?topic=10174.msg268372#msg268372 ? Would be interesting to see if that's really the same violation as what I'm observing in the simple RC circuit (by analyzing the raw data transparently in Excel and not using the PSpice analysis tool).

[Pirate88179]

It's quite simple really. A "dead" battery may have little voltage available at its terminals, but it still contains energy and current can still be drawn from it by shorting it out. The JT shorts out the battery through the collector coil and draws current. When the transistor turns off, the inductive kickback manifests as a high voltage spike which is much higher in amplitude than is required to turn on the LED.

So in effect, the JT is a converter of sorts; it converts a current (which we can still extract from the dead battery) into a high voltage, which is able to forward bias a LED or string of LEDs.

Does that make sense?

Bill, have you ever installed a high power audio amplifier in your vehicle? It works on a similar principle, but the goal there is to increase the power amplification beyond what can be achieved using only the 12VDC available from the vehicle battery. A large part of the after-market power amplifier is the power supply; it converts (i.e. raises the voltage) 12VDC to perhaps +/- 35V or so, similar to what your home theatre amplifier might use.

.99

Yes, I agree with your explanation but, I was meaning something else.  What I was trying to say was, if these have been around forever, and are totally understood, why can't we buy commercially produced devices that utilize this circuit?  Like my flashlight example.  More light, brighter and longer lasting on a single AA instead of 3.

I have to admit that the tiny circuits inside of some of the solar led garden lights I have been playing with lately appear to be pretty efficient in acting both as a controller for the charging of the bat. and stepping up the voltage from 1.2 to 3.2 volts.

The most efficient JT circuits I have built do not use batteries at all.  I use supercaps which charge up right away and last a longer time, possibly for the same reason as you mentioned above for the batteries.  I first began doing this about 3 years ago but now, the supercaps are both cheaper, and larger in capacity.

Thanks,

Bill

[MrMag]

Yes, I agree with your explanation but, I was meaning something else.  What I was trying to say was, if these have been around forever, and are totally understood, why can't we buy commercially produced devices that utilize this circuit?  Like my flashlight example.  More light, brighter and longer lasting on a single AA instead of 3.

Most of the flashlights are built by the battery companies