Is joule thief circuit gets overunity?

[Void]

@Void

The Zhou Boards showed much ringing - heard by the many young ears.  (I could not hear any but that was probably due to my poor hearing.)  I shall use different time scale to show the ringing waveforms.

I noticed that the display of your DSO is exactly like Atten.  That will make our communication much easier.  You can use the save/recall button to save the CSV file on the USB.  I can analyze one of your measurements for you (both Input and Output) as sample.  You do not need to rely on Vrms values any more.  You can use the vigorous Instantaneous Values.

Yes, your boards seem to show a lot more ringing than my circuit, and they also show some unusual pulses/noise superimposed on the waveforms as well, which may be just due to electrical noise of some sort, but I don't know. It might be something else causing those pulses. My super capacitor is actually 3000 Farads nominal value, so it is going to take a fair bit of time for the input voltage to drop down much below 0.4 volts. It is the only super capacitor I had available however. My joule thief circuit has been running all day and the input voltage is still at 400mV from 408mV yesterday evening. It might be a day or two before the voltage has dropped down much below 400mV. The ringing that can often be heard on a joule thief circuit is generally due to the frequency of oscillation being in the audio frequency range, which causes the ferrite to ring at that frequency for some reason, and probably not so much to do with the type of ringing pattern that can be seen on the input current waveform. My joule thief circuit seems to operate mainly above the audio frequency range, at least at the lower input voltages I have been testing it at, so I don't hear any ringing noise from my ferrite toroid. I will see if I can get the data logging working on the weekend. If I can do it using a USB flash drive, I would prefer that because hooking up to a laptop will likely increase the electrical noise in the test circuit. Laptops and their switching power supplies tend to produce a fair bit of electrical noise.

[Pirate88179]

@Void

The Zhou Boards showed much ringing - heard by the many young ears.  (I could not hear any but that was probably due to my poor hearing.)  I shall use different time scale to show the ringing waveforms.

I noticed that the display of your DSO is exactly like Atten.  That will make our communication much easier.  You can use the save/recall button to save the CSV file on the USB.  I can analyze one of your measurements for you (both Input and Output) as sample.  You do not need to rely on Vrms values any more.  You can use the vigorous Instantaneous Values.

Lawrence:

If your students can hear the ringing, then your JT's are operating under 20,000 cycles/sec.  (Possibly a little higher, but not much)  Some of the JT lights I have built made that annoying high pitched buzz so I simply placed a small neo on the ferrite toroid and it raised the HZ above my hearing level...and also made the lights a little brighter.

Note that Void's frequencies are much higher and that is why he can't hear them.

Just my 2.1175 cents.

Bill

[ltseung888]

Analyzing the Noise.  Look at the following 5 slides.  The noise is relatively systematic.

What can it be???

[Void]

Analyzing the Noise.  Look at the following 5 slides.  The noise is relatively systematic.
What can it be???

I am not sure, as your input current waveforms look a lot different from mine.
Would you mind showing a scope shot with everything else still connected the same,
but with one of the input power wires disconnected, or with the power turned off?
This will give an indication of what kind of electrical noise the circuit is picking up
when the circuit is turned off, so we can see what sort of noise remains.

[Void]

Here is a scope shot of the input waveforms of my joule thief circuit with the super cap now at about 384mV.
The input current waveform still looks fairly similar to the way it looked at 408mV, but the frequency
slowly increases as the input voltage drops. The frequency is now around 294kHz at this input voltage.