Not just that, also "push new charge in" when it needs to turn on again. Must be carefully metered out though, you don't want to fry the LED. It's like making coffee for the first time, add spoons until the brew is just right, strong enough for good taste but not so strong that people complain about cardiac issues :-)
-- Regards, Joerg http://www.analogconsultants.com/
This is another must-have if you're messing with radiation...
It's sort of like Phil's book, a lot of specfic stuff about the physics, and a nice dollop of electronics.
(I like that word, "dollop." It sounds good, like "ramekin."
Hey, this is new. In igoogle, if I type dollop without anything else, a definition pops up below the search box.
for free,
what was it ? tritium-,
(?),
Some plutonium gadgets do use a hollow sphere. In the center they put the initiator, and maybe some tritium as a booster.
Plutonium bombs usually do compress the plutonium to maybe 2x normal density. At peak compression, neutrons are generated at the center to seed the chain reaction.
Another good book:
It's amazing how much they knew in 1942.
John
te.
d f=3D
e i=3D
Nice Thread... I'm enjoying all the ideas.
I was thinking of the spinning mirrors in bar code scanners.
But maybe a little mirror on a little flexure driven by a piezo stack. If you keep mass down if can vibrate fairly fast. I use these little piezos that move ~10um with a resonance freq. above 400kHz.
George H.
I think I still have a few of the motor and front surface mirror sets that are good. I scrapped a bunch of big cast aluminum scanners about
15 years ago. I sold the aluminum & the HeNe LASERs, but kept the optics & detector modules.-- You can't have a sense of humor, if you have no sense.
=20
Yep, that's a classic solution. LEDs are fast to modulate, but they have (at low currents) reciprocity failure, and at moderate currents the output might go through directional changes. =20 For metrology, use any feedback-regulated source (incandescent=20 is not bad) and well-understood geometry (rotating-slotted-disk) for modulation, with attenuation by stacked calibrated ND filters (neutral density). Rotating mirror and a slit, backed by a lens, is good, too.
Soldered togetehr a 4046, generates a few kHz, drives bkue LED via potmeter and 100K series resistro from 0-5V square wave.
Houston we have a problem... LED noise or PMT noise?
Useless for spectrum analysis, no resolution left.
This is the same software and hardware with a signal from sgan (Linux signal genarator) with as output a 10% duty cycle pulse:
Never mind all the mixer stuff, I use ALSA mixer and xmixer at the same time.. PMT output is on mike input, new circuit:
+5 | 1k 2500 uF to get a riple free supply |--------|| |----- 1k5 | | /// |---------------------||-------> mike input --3M9--| 4nF | c (but 64 uF in test to see the LED square wave) |-- ---- b PMT e BC547-B anode | ///The LED is in a cardboard tube with black plastic covering it at about 20 cm from the PMT front.
_______________________________________________________ | || | -------------== ) | PMT | ]============ | LED -------------== |_______________________________________________________||
PMT noise or LED noise? Have to think about that.
The software works OK:-)
(...)
Don't start a kerfuffle about it, though.
--Winston
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