Satcure Circuit Frequency

[APW]

I got this plots from an oscilloscope just to show you how Satcure work with just the simple 3 components - transistor, ferrite bead with winding and a 2K resistor.

For 1 White LED driven by 1AA

http://members.tripod.co.uk/APW/1AA1LED.jpg
It shows about 25kHz. Though voltage up to 6V (instantaneous) but the brightness is similar to 3.4V. The efficient part is when the voltage drop gradually from 3.8V to 3.0V giving an average 3.4V I suspect

Then I put 2AA in to drive 4 LEDS in parallel to brightness similar to 3.6V (to drive 1 LED by 2AA would cause overheating)

http://members.tripod.co.uk/APW/2AA4LED.jpg
It gives 35kHz. Voltage drop from 4.2V to 3.0V giving average around 3.6V and so driving a full brightness. And I find it best to drive them this way and get the full brightness without overheating the LEDs.

Cheers
Andy

 

[APW]

Kenbar,

I will try with 2 bead as well later.
Then hook to the oscilloscope again to see how the voltage drop

Theoretically, the winding acts as oscillator, transformer and inductor.
More winding means induce more magnetic flux and hence higher current. More Ferrite Bead may also produce more current. But I have no idea about the voltage pattern. It is dependent on no. of batteries, number of LEDs and Parallel/Series, it is a bit weird.

No load conditions (No LEDs) will produce more than 30V but just hook an LED it becomes something like the plots. No negative Voltage occurs, it is purely oscillating at positive area.

Cheers
Andy

 

[Go Go Gadget Flashlight]

Andy, try a cap across the output and see what the LED loaded voltage is. Should be smoother and not require a diode if it is truly positive pulse.

Good job!

 

[Go Go Gadget Flashlight]

Any further progress?

 

[APW]

Nope! Haven't got a capacitor yet.
Have tried comcining 2 bead and wind 25 turns but not much brigther than with 1 bead and driven with 1AA

Will try capacitor later

Andy

 

[Go Go Gadget Flashlight]

Cool. Keep us posted as you progress.

 

[APW]

Gadget,

I simply pick up a cap from Old Speaker rated 1 microF & 50V and put across the output to the LED

Here is the plot

Well as you can see, not up to 3V, lower freq. and so it is very dim.

Can you try to put different type of caps across the LED without the diode and see what happen?

Cheers
Andy

 

[X-CalBR8]

I remember someone mentioning earlier that this circuit works by saturating the ferrite core, so why not use the same turns of the same sized wire and just use a slightly larger ferrite bead? If it works by saturating the ferrite bead, then shouldn't a slightly larger bead = a slightly larger voltage/current? There should be more mass there to be saturated. Let me know what you think of this theory. I noticed that Hosfelt has about a half dozen different ferrite beads and I thought I would get the largest one that they have and try building the Satcure circuit around it and see what happens. Have you guys tried building the Satcure circuit using different sized beads yet to see what the results would be?

 

[KenBar]

Your wish WAS my command..LOL
I ordered all of them plus the split core.
I also emailed Martin in England ( Satcure ) for a tip/s using 2 transistors.

THEN....this latest Eternalight event happened and all is sitting on my desk still in the Hosfelt box.

I needed to do one more email trying to clarify exactly what saturated meant. I know the definition...but the logic behind it. What happens just before saturation is reached? Oversaturation?? Why does a 4 cent transistor perform better (use less current) than a $1.00 high efficiency one. The whole thing has me stumped.

How does wire diameter play in the design? Can it be too big?..too small... I think I am getting better results from the wire I ordered from Satcure than the wire that Gadget gave me. England wire is a TAD bigger around.

Why, when you bring a strong magnet near the core, the light slowly dims...like a rheostat.. Current decreases, but does not die totally. Then as you move it away, the light brightens.

With a split core, it sure as heck will make winding them easier...if it works.

My only problem is incentive. I really like this eternalight/pal light so much I sort of am satisfied to rest a bit....plus I have started learning Bulgarian today. I have 6 months to come up to speed. I have tried listening to the CD and making flashlights and the two don't mix at all.

 

[Go Go Gadget Flashlight]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by KenBar:
I needed to do one more email trying to clarify exactly what saturated meant. I know the definition...but the logic behind it. What happens just before saturation is reached? Oversaturation?? Why does a 4 cent transistor perform better (use less current) than a $1.00 high efficiency one. The whole thing has me stumped.<HR></BLOCKQUOTE>

Saturation would be the point of best efficiency (I think).
The 4 cent transistor may be working at a higher or lower frequency. This would affect the saturation level of the core. The "good" transistor may have cycled so fast that the core never saturated.

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>How does wire diameter play in the design? Can it be too big?..too small... I think I am getting better results from the wire I ordered from Satcure than the wire that Gadget gave me. England wire is a TAD bigger around.<HR></BLOCKQUOTE>

The bigger the wire, the lower its resistance. Since resistance affects the frequency, it will affect the output, too. Since my wire is smaller, maybe fewer turns would work better.

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Why, when you bring a strong magnet near the core, the light slowly dims...like a rheostat.. Current decreases, but does not die totally. Then as you move it away, the light brightens. <HR></BLOCKQUOTE>

You're screwing up the magnetic field in the core with the external magnet.

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>With a split core, it sure as heck will make winding them easier...if it works.<HR></BLOCKQUOTE>

The split core will have a much different operating frequency and saturation. Easy to wind, but may be a booger to get it to work. Let us know.

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>My only problem is incentive. I really like this eternalight/pal light so much I sort of am satisfied to rest a bit....plus I have started learning Bulgarian today. I have 6 months to come up to speed. I have tried listening to the CD and making flashlights and the two don't mix at all.<HR></BLOCKQUOTE>

ROFLMAO!!! I imagine Bulgarian is hard enough when you are actually paying attention!

Disclaimer: The explanations presented here are entirely speculations of a mechanical engineer. Corrections are forthcoming (from other members).