Without the benefit of agressive low pass filtering the noise of an LT3042 at
10Hz is at least an order of magnitude worse than that of an unfiltered LED for
the same output voltage.
The noise of Nitride passivated LEDs degrades significantly with aging and
there is a strong correlation between
There are some NIR sensitive photodiodes that take advantage of the NIR
transparency of some black epoxies.
Bruce
> On 20 August 2018 at 02:48 Dana Whitlow wrote:
>
>
> Be watchful about the black epoxy. It may just be a dyed (otherwise
> clear) epoxy,
> and some of the black dyes in common
Also check your red LEDs. I have some that have a Vf of over 3V. They could
be a blue LED/phosphor (not likely, blue -> red conversion is rather
inefficient) or two red LEDs in series.
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To
Am 19.08.2018 um 14:43 schrieb Bruce Griffiths:
Yes, I looked at the plots and I see exactly what I described.
2nV/rtHz at frequencies somewhat above the reference current source output RC
filter, rising to a high value at frequencies below the current source output
filter pole.
This is an
Be watchful about the black epoxy. It may just be a dyed (otherwise
clear) epoxy,
and some of the black dyes in common use pass near IR quite readily. This
would
probably be most troublesome if the ambient light source were of the
incandescent
persuasion.
Also, small diodes in clear packages
That's a very good point. I have used LEDs as photocells many times, the
first time was in 1974 when it was easier for this university student to
get LEDs than photocells.
I have also made a bi-directional optically isolated data link using a
single fiber optic cable and two fiber optic
Yes, I looked at the plots and I see exactly what I described.
2nV/rtHz at frequencies somewhat above the reference current source output RC
filter, rising to a high value at frequencies below the current source output
filter pole.
This is an inherent property of the architecture.
The LT3042 is
Am 19.08.2018 um 10:22 schrieb Bruce Griffiths:
Rick
I devised the bias circuit for the TNS-BUF.
It exploits the fact that for a RED LED at least the difference between the LED
forward voltage and the transistor Vbe is ~ 1V and has a fairly low tempco and
has low noise (at least for RED
We just got word that the new batch of TNS-BUF isolation amplifier
boards have made it through customs and are on the way to the TAPR
office. If you have one on order, it should be going out next week.
We do have a few extra boards available if anyone needs one:
https://tapr.org/kits_tns-buf
