T
Tim Williams
- Jan 1, 1970
- 0
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Pictures of the Internet's Largest Joule Thief
T
Tim Williams
- Jan 1, 1970
- 0
Whoops,
Here's the array, assembled:
http://webpages.charter.net/dawill/Images/LED_Array_1.jpg
http://webpages.charter.net/dawill/Images/LED_Array_2.jpg
http://webpages.charter.net/dawill/Images/LED_Array_3.jpg
LEDs on collector/inductor. Worked right off the bat. Waveform showed kind
of weird turn-on behavior though:
http://webpages.charter.net/dawill/Images/LED_Array_4.jpg
Reducing the series base resistance cleaned that up.
Overshoot on the collector waveform is mostly due to the long emitter lead
(these waveforms were measured with respect to the emitter, at the package),
which made about a 1/2" loop. I fixed that.
The revision: trying it with a schottky rectifier.
http://webpages.charter.net/dawill/Images/Ten LED Inverter.gif
Glowing:
http://webpages.charter.net/dawill/Images/LED_Array_5.jpg
http://webpages.charter.net/dawill/Images/LED_Array_6.jpg
View of the new hardware:
http://webpages.charter.net/dawill/Images/LED_Array_7.jpg
10uF ceramic chip is the tan blob just left of the schottky, which is a
Shidengen M2FH3. Collector waveform is a clean, flat square wave with
little overshoot, 2V peak to peak. Output was a constant 1.85V with under
10% ripple -- the LEDs have a pretty high impedance relative to that
big-stinkin'-ceramic-which-is-actually-small-stinkin'-SMT. A little
overshoot on switching, of course, but really only an artifact of the
wiring.
Tim
Here's the array, assembled:
http://webpages.charter.net/dawill/Images/LED_Array_1.jpg
http://webpages.charter.net/dawill/Images/LED_Array_2.jpg
http://webpages.charter.net/dawill/Images/LED_Array_3.jpg
LEDs on collector/inductor. Worked right off the bat. Waveform showed kind
of weird turn-on behavior though:
http://webpages.charter.net/dawill/Images/LED_Array_4.jpg
Reducing the series base resistance cleaned that up.
Overshoot on the collector waveform is mostly due to the long emitter lead
(these waveforms were measured with respect to the emitter, at the package),
which made about a 1/2" loop. I fixed that.
The revision: trying it with a schottky rectifier.
http://webpages.charter.net/dawill/Images/Ten LED Inverter.gif
Glowing:
http://webpages.charter.net/dawill/Images/LED_Array_5.jpg
http://webpages.charter.net/dawill/Images/LED_Array_6.jpg
View of the new hardware:
http://webpages.charter.net/dawill/Images/LED_Array_7.jpg
10uF ceramic chip is the tan blob just left of the schottky, which is a
Shidengen M2FH3. Collector waveform is a clean, flat square wave with
little overshoot, 2V peak to peak. Output was a constant 1.85V with under
10% ripple -- the LEDs have a pretty high impedance relative to that
big-stinkin'-ceramic-which-is-actually-small-stinkin'-SMT. A little
overshoot on switching, of course, but really only an artifact of the
wiring.
Tim
M
Michael
- Jan 1, 1970
- 0
Tim said:
Very much in season!
"Kling, circuit, kling-a-ling-a-ling..."
(to paraphrase a German Christmas carol)
M
Michael
- Jan 1, 1970
- 0
Jan said:
Yet another Christmas carol!
"Hark! The al-ca-line is shreaking..." ;-)
R
Reinhard Zwirner
- Jan 1, 1970
- 0
Tim said:
Hi,
what kind of transistor is this KSC5001 (okay, npn BJT): I couldn't
find any datasheets on the Internet?
CU
Reinhard
A
Archimedes' Lever
- Jan 1, 1970
- 0
T
Tim Williams
- Jan 1, 1970
- 0
Ermm....
KTC I think?
The classic 2SC works, too.
Tim
KTC I think?
The classic 2SC works, too.
Tim
R
Reinhard Zwirner
- Jan 1, 1970
- 0
Tim said:
Hello Tim
Thank you very much: now I could find a datasheet
!Perhaps you might think about correcting the schematic to avoid
similar questions in the future ...
Best regards
Reinhard
J
James Arthur
- Jan 1, 1970
- 0
Tim said:
Neat. I've been away--sorry to have missed your earlier
question about windings. Yours look ample.
10% voltage ripple means a _lot_ of current ripple feeding
an LED load. A bigger filter cap would save wastage in the
LEDs' e.s.r.
Any measurements? Pout/Pin ? Updated waveforms?
Cheers,
James Arthur
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