pin diode

Guest
Hi,

What is the difference between Light Detector Resistor and a pin diode?

And which one is better to use for solar tracking purposes and why? For example

LDR:

http://www.digikey.com/product-detail/en/PDV-P8104/PDV-P8104-ND/480611


PIN DIODE:

http://media.digikey.com/pdf/Data%20Sheets/Everlight%20PDFs/PD204-6C.pdf

mel
 
On Thu, 03 Dec 2015 20:59:21 -0800, walravenmelissa wrote:

Hi,

What is the difference between Light Detector Resistor and a pin diode?
Click to expand...

PIN photodiode.

In the photoresistor the CdS is a semiconductor that's more or less
neutrally doped (I think); light striking it generates carriers (electron-
hole pairs) that help it to conduct electricity.

In the photodiode, it's a real live actual diode. Light striking it
generates carriers that make it act like a diode in parallel with a
current source. Depending on how you connect it, the diode will either
generate a voltage that can be sensed or it will pass a current that can
be sensed.

And which one is better to use for solar tracking purposes and why? For
example

LDR:

http://www.digikey.com/product-detail/en/PDV-P8104/PDV-P8104-ND/480611


PIN DIODE:

http://media.digikey.com/pdf/Data%20Sheets/Everlight%20PDFs/PD204-6C.pdf
Click to expand...

Six of one, half a dozen of the other. Cadmium is toxic; I'm not sure if
that matters much at all in a CdS cell, but if the ROHS nazies ever come
to your door you'd like to be clean.

I'm more familiar with the care and feeding of photodiodes, so I'd
probably use them (aren't they cheaper, too?). I'd probably use them in
photovoltaic mode, because their voltage will be roughly logarithmic to
illumination, meaning that the voltage difference between a pair of them
will be fairly constant with illumination. (Come to think of it this
won't matter much because if it's very cloudy the sun will appear to be
defocused -- oh well, I'd use 'em in photovoltaic mode anyway).

Why not just use an ephemeris and clockwork? That way your rig can
always point at the sun regardless of whether it's behind the clouds,
eclipsed, or gone out entirely.

--
www.wescottdesign.com
 
I was wondering that which option pin diode or LDR is better to track the sun. I meant which one has the better I do not know how to say it has better light properties. Lets say that one LDR or pin diode is mounted on the east side and the other on the west side. The motor will move until the difference between the two sensors becomes zero.

Lets say tracking algorithm is not an option. which option you will go with?
 
They both are very cheap. That's true that my application is slow and does not require lots of sensitivity.

But I am leaning towards pin diodes. You said that they are fast. How are they faster and sensitive than Light Detection resistor? Do pin diodes have better spectral properties than LDR. I have posted the link of the pin diodes in the OP. They are cheaper and how can I use them instead of LDRs?
 
On Thu, 3 Dec 2015 20:59:21 -0800 (PST), walravenmelissa@gmail.com
wrote:

Hi,

What is the difference between Light Detector Resistor and a pin diode?

And which one is better to use for solar tracking purposes and why? For example

LDR:

http://www.digikey.com/product-detail/en/PDV-P8104/PDV-P8104-ND/480611


PIN DIODE:

http://media.digikey.com/pdf/Data%20Sheets/Everlight%20PDFs/PD204-6C.pdf

mel
Click to expand...

Solar tracking with light diodes is stone-age technology.
SUN travels 15 degrees per hour and all you need
is a small geared motor which makes a few turns every five minutes.
A simple garden or household timer clock does that easily.
The gear ratio has to be designed appropiately.
End position switch sends it back to the morning position,
like the windshield wipers in a car.
Elevation to be corrected twice a year, or just leave it as is.

No tracking, no calculations, not complicated control circuits.
Your sun diodes will always point to the brightest spot in sky
which may be a cloud in any direction.

w.
 
"Tim Wescott" <tim@seemywebsite.com> napisał w wiadomości
news:dMqdnXV6w4lDqPzLnZ2dnUU7-SGdnZ2d@giganews.com...
On Thu, 03 Dec 2015 20:59:21 -0800, walravenmelissa wrote:

Hi,

What is the difference between Light Detector Resistor and a pin diode?

PIN photodiode.

In the photoresistor the CdS is a semiconductor that's more or less
neutrally doped (I think); light striking it generates carriers (electron-
hole pairs) that help it to conduct electricity.
Click to expand...

Generated or induced?
See:
https://archive.org/stream/radiationlightil00steirich#page/14/mode/2up
and:
http://pvcdrom.pveducation.org/MANUFACT/FIRST.HTM
"Edmond Becquerel appears to have been the first to demonstrate the
photovoltaic effect (Becquerel, 1841a, , 1841b). Working in his father's
laboratory as a nineteen year old, he generated electricity by illuminating
an electrode with different types of light, including sunlight (see the
figure below)."

Steinmetz wrote that the radiation induce the charge to the antenna.
Becquerel that the radiation generate the electricity (current) in the
circuit.

Who, when i for what invented the electron- hole pairs?
S*
>
 
On 12/04/2015 05:59 AM, walravenmelissa@gmail.com wrote:
Hi,

What is the difference between Light Detector Resistor and a pin diode?

And which one is better to use for solar tracking purposes and why? For example

LDR:

http://www.digikey.com/product-detail/en/PDV-P8104/PDV-P8104-ND/480611


PIN DIODE:

http://media.digikey.com/pdf/Data%20Sheets/Everlight%20PDFs/PD204-6C.pdf

mel
Click to expand...
I think the pin diodes are a bit faster than LDR. some people use LEDs...
If neither speed nor sensitivity really matters for your application,
just use what is cheapest...
 
On 12/04/2015 01:42 AM, Tim Wescott wrote:
On Thu, 03 Dec 2015 20:59:21 -0800, walravenmelissa wrote:

Hi,

What is the difference between Light Detector Resistor and a pin diode?

PIN photodiode.

In the photoresistor the CdS is a semiconductor that's more or less
neutrally doped (I think); light striking it generates carriers (electron-
hole pairs) that help it to conduct electricity.

In the photodiode, it's a real live actual diode. Light striking it
generates carriers that make it act like a diode in parallel with a
current source. Depending on how you connect it, the diode will either
generate a voltage that can be sensed or it will pass a current that can
be sensed.

And which one is better to use for solar tracking purposes and why? For
example

LDR:

http://www.digikey.com/product-detail/en/PDV-P8104/PDV-P8104-ND/480611


PIN DIODE:

http://media.digikey.com/pdf/Data%20Sheets/Everlight%20PDFs/PD204-6C.pdf

Six of one, half a dozen of the other. Cadmium is toxic; I'm not sure if
that matters much at all in a CdS cell, but if the ROHS nazies ever come
to your door you'd like to be clean.

I'm more familiar with the care and feeding of photodiodes, so I'd
probably use them (aren't they cheaper, too?). I'd probably use them in
photovoltaic mode, because their voltage will be roughly logarithmic to
illumination, meaning that the voltage difference between a pair of them
will be fairly constant with illumination. (Come to think of it this
won't matter much because if it's very cloudy the sun will appear to be
defocused -- oh well, I'd use 'em in photovoltaic mode anyway).

Why not just use an ephemeris and clockwork? That way your rig can
always point at the sun regardless of whether it's behind the clouds,
eclipsed, or gone out entirely.
Click to expand...

Hmm. I wonder if Melissa has ever met erica.cross? Maybe in the mirror?

Cheers

Phil Hobbs
 
On Friday, December 4, 2015 at 4:53:21 AM UTC-8, walrave...@gmail.com wrote:

[about CdS light-dependent resistors (LDR) versus PIN diodes as light sensors]

> But I am leaning towards pin diodes. You said that they are fast. How are they faster and sensitive than Light Detection resistor? Do pin diodes have better spectral properties than LDR. I have posted the link of the pin diodes in the OP. They are cheaper and how can I use them instead of LDRs?

A photodiode will generate a small current (so it needs an amplifier of some sort) and
benefits from regulated bias voltage, or from feedback that keeps it at zero voltage.
An LDR, on the other hand, can operate on AC line voltage.

Spectral sensitivity is important? Why? Both will detect daylight.
Sensitivity is important? Why?
Speed is of interest? Why? Either will react in under a second.
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top