Joule Ringer!

[e2matrix]

Nice work conrad.  I found a TIP41C last night.  Do you think those would work about the same as the TIP31c?  I haven't tried using a diode on the base as I found it last night but so far no luck with it. 

[conradelektro]

Again I little better, MPSA06 and TIP31C Darlington pair.

With this strange Darlington pair (MPSA06 and TIP31C) and C3=100pF, I get the impression that the 0.6 Watt version is a little brighter than with two TIP31Cs. Still there is this strange double triggering at the base of the transistor (which probably prohibits even better performance).

@Stefan (hartiberlin): a diode between base of transistor and GND does not prohibit the formation of negative spikes, it is the diode between trigger coil and base that does this. A zener diode between base and GND could limit the positive spike at the base (but it is so small anyway in my circuit).

@e2matrix: TIP41C should work (I do not have any), especially in combination with a MPSA06. I think your trigger coil is the problem. It is not so easy to find a good trigger coil in a fly back transformer, some might not have any useful trigger coil at all. One could try a Slayer Exciter version in this case (secondary at the base of the transistor, as some people did successfully with their fly back transformer). Further up in this thread I posted a Slayer Exciter with a big tower coil and you could use this circuit with your fly back transformer.

It is also difficult to get C1 and R1 right. One should start with R1 = 100K and change C1 between 1 nF, 10nF, 100nF and 1000nF till it works. Once it works, careful adjustment of R1 then defines the power consumption.

I find, that the diode between trigger coil and base of the transistor is important. C3 (parallel to this diode) is only a little touch.

Also C2 has an influence, should be at least 100 uF.

I am still waiting for delivery of ten different fly back transformers (for obsolete PC-monitors). Once they are here, I will go into that "trigger coil problem". I also think that my little (yellow) fly back transformer (which I used for all the circuits I talked about lately) has a no good trigger coil, hence this strange double triggering I am measuring. The trigger coil in a Joule Thief type circuit must have a certain strength (Voltage of the signal and Amperage to sustain it over the switching of the transistor). If the trigger signal is too strong, one can do something (diode between trigger coil and base, and zener diode between base and GND), but if the signal is too weak, no luck.

Greetings, Conrad

[the_big_m_in_ok]

Heres my setup - I'll post a video soon.

@flathunter , in regard to Reply #187, Page 13
I like the circuit, but the photo size is extensive, all over the screen, until I invoke the .JPG link at the bottom.  It fills up the page then, and it printable.

It really is an unusual diagram.  Reminds me of a Tesla coil with a power takeoff coil over the tower coil.

Have you built one yet?  If so, did you get it to function in electrical resonance?

--Lee

[nul-points]

the schematic above is drawn with the 2 diodes on the AV plug reversed

as shown they'll charge the capacitor with a -ve voltage for the darlington collector supply (NPN needs +ve supply)

they should be pointing in the same sense as the Zener diode addition given by Conrad

[wings]

I studied some more the basics of capacitors and what we probably have here with the
Joule Ringer is, that the short discharge pulses are just recharged by dielectric absorption:

http://en.wikipedia.org/wiki/Dielectric_absorption

Dielectric absorption is the name given to the effect by which a capacitor that has been charged for a long time discharges only incompletely when briefly discharged. Although an ideal capacitor would remain at zero volts after being discharged, real capacitors will develop a small voltage, a phenomenon that is also called soakage or battery action. For some dielectrics, such as many polymer films, the resulting voltage may be less than 1-2% of the original voltage, but it can be as much as 15 - 25% for electrolytic capacitors or supercapacitors.

http://en.wikipedia.org/wiki/Types_of_capacitor#Dielectric_absorption_.28soakage.29

Some types of dielectrics, when they have been holding a voltage for a long time, maintain a "memory" of that voltage: after they have been quickly fully discharged and left without an applied voltage, a voltage will gradually be established which is some fraction of the original voltage. For some dielectrics 10% or more of the original voltage may reappear. This phenomenon of unwanted charge storage is called dielectric absorption or soakage, and it effectively creates a hysteresis or memory effect in capacitors.

The percentage of the original voltage restored depends upon the dielectric and is a non-linear function of original voltage.[2]

In many applications of capacitors dielectric absorption is not a problem but in some applications, such as long-time-constant integrators, sample-and-hold circuits, switched-capacitor analog-to-digital converters, and very low-distortion filters, it is important that the capacitor does not recover a residual charge after full discharge, and capacitors with low absorption are specified[3]. For safety, high-voltage capacitors are often stored with their terminals short circuited.

Some dielectrics have very low dielectric absorption, e.g., polystyrene, polypropylene, NPO ceramic, and Teflon. Others, in particular those used in electrolytic and supercapacitors, tend to have high absorption.


http://de.wikipedia.org/wiki/Kondensator_%28Elektrotechnik%29#Temperaturabh.C3.A4ngigkeit

Kondensatortyp                                                     Dielektrische Absorption
Kunststoff-Folienkondensatoren, Polyesterdielektrikum    0,2 bis 0,25 %
Kunststoff-Folienkondensatoren, Polypropylendielektrikum    0,01 bis 0,05 %
Keramikkondensatoren, X7R                                            0,6 bis 1 %
Keramikkondensatoren, Z5U                                            2,0 bis 2,5 %
Aluminium-Elektrolytkondensatoren                                    etwa 10 bis 15 %


So alufoil electrolyte caps can have an automatic  recharge rate of 15 % due to
dielectric absorption !

So it really depends also on what kind of electrolyte capacitor you are using for the Joule Ringer circuit.

It must be a cap that has a high dielectric absorption !

from:
http://www.keith-snook.info/capacitor-soakage.html

"For any fixed charge { Q } on the plates of a capacitor the voltage will fall if the plates move together { V=Q/C } and will increase if the plates move apart â€" If a dielectric material can be readily compressed and relax back because it is made of fibrous paper soaked in oil and or the foil of the plates is loosely wound then the plates will move together as the capacitor is charged â€" The value of C will increase and give a greater charge Q for any applied voltage

After a rapid charge and removal of the supply â€" the voltage across a capacitor can rise beyond the supply voltage which is most likely due to the compressed dielectric relaxing back to its natural position and its original value of C â€" After a rapid discharge â€" where the high current pulls the plates together â€" the remaining low voltage will rise as the residual charge on the plates is again subjected to decreasing C as the dielectric relaxes back â€" These effects are easy to measure but not easy to isolate from other effects like chemical and molecular changes in the dielectric"

parametric effect?