Not digital watches. They just lay there and do nothing.
To help us out, it would be best if you describe your
I see what you're asking.
gnd gnd
Zero-beat to WWV is hard to do better than 50Hz by ear. Mechanical
Here are some measurement of a few Epson Type 2 60 kHz crystals I made
You forgot to add: "that when the user notices less than satisfactory
Richard Cappels had a project on his web page that replaced one cell
There are only 8 colors. Anyone who tells you that there are more is
That's what he said... 10^18 smaller
Just be careful with these. A GHz transistor can oscillate without you
If there's enough torque behind the needle to move the wiper that could work.
JTAG is the usual method to see if the pins are at least toggling - great
The higher-voltage ones ARE pin diodes. They can make excellent driftLostgallifreyan wrote:
Joerg <invalid@invalid.invalid> wrote in
news:7dbdd3F2b0r74U2@mid.individual.net:
Lostgallifreyan wrote:
If anyone is following this and wants to try modelling their own stuff,
I found what might be a way.
Intusoft make a tool called SpiceMod which is part of a package they
call ICAP4 though it seems the demo setup doesn't have that tool, just
some very good noted on it, and modelling in general:
The file WkwModels.pdf from the demo install answers a lot fo the
questions I had about modelling diodes, which parameters to tweak, and
extraction from data sheets.
I don't know if the lack of response to me is because of a thousand
experts silently screming RTFM at me, or because it's actually
asomething they DON'T KNOW. Given that Intusoft explain that this is a
serious challenge for experts too, I'm assuming maybe they really don't
know, so they might benefit from that file as much as I will.
Most of us just use a regular diode to simulate because all one
(usually) wants to know is that there definitely won't be any ever so
slight spike in diode current because LDs can go poof in microseconds.
Simulating the optics part would be a major challenge, I think.
Thought that might provoke an expert.
usually need too, though like that EDN manual says, a more detailed model
that allows models to give warning of imminent demise is useful. Modelling
for ESD is likely daft, better that we just take care and put in TVS's and
such, but when it comes to fast modulation, a model definitely helps. Surely
you'd have a use for that, no?
I have designed LD circuitry but I am not an expert. Senor Hobbs would
be one. TVS don't work well. Their cutoff isn't terribly well defined
and they have too much capacitance for this. Just handle the things with
care. I've never killed one with ESD, knock on wood ;-)
While I found that a string of four 1N4148's produced a modelled overshoot
almost exactly like what I saw on an oscilloscope months before I considered
looking at spice, I got a very different result when trying four 1N4001's so
it really does need something better than reaching for a standard diode, in a
model OR as a dummy diode in a real circuit (where a optically dead laser
diode is best anyway). So it really comes down to trying to get something
usefully close! EDN's model seems ideal, aimed at solving this problem for
general use, as opposed to the elaborate models in private university
publications. EDN's is probably tested too, proofread and verified before
publishing.
http://www.e-insite.net/ednmag/archives/1998/071698/pdf/15di.pdf
(Halfway through file).
"File not found" :-(
Some of the 4000 series behave more like PIN diodes.
You can build a current drive out of a LM317, I've even used it as an AMLostgallifreyan wrote:
Joerg <invalid@invalid.invalid> wrote in
news:7dc0a0F2aeembU1@mid.individual.net:
Ringing? I never had that. Don't drive them through a built-in
inductor
Not intentional.. I'm using an LM317. Yes, I know it's not the
approved way. It WORKS, far better than expected, and most people who
explore weird tricks with an LM317 are mightily impressed with it,
from the guy who built a class A headphone amp, or the radio ham who
built a transmitter round one...
My physical circuit build, AND the later spice modelling, both
indicate that an LM317 for a cheap way to get up to an amp-amd-a-half
of DC coupled proportional laser drive at up to 500 KHz is very likely
to work well. Maybe the inductance is in the LM317 model, I don't know
where else it can be in my simple circuit models. What's crucial is
that it is the SAME overshoot I saw in the real circuit so spice is
already telling me good things, and I've already improved the driver
on the strength of that spice model.
Ohhhhhh..... You're using a voltage driver, and trying to trick it into
being a current driver. Bad, bad, bad, bad news.
Due to the rolloff in the loop gain, the output of a voltage regulator
appears inductive, which will reliably give you a big noise peak if the
output cap is too big, and some ringing if it's too small. As Joerg
said, you're way better off using current drive. It isn't difficult,
just an op amp and a Darlington. Use the Darlington's collector as the
output, and sense the current in its emitter. Adding an outboard
current limit is easy then too.