Using LEDs as photovoltaics

[Martin Brown]

On 12/11/2019 07:15, Clive Arthur wrote:

On 12/11/2019 03:44, jlarkin@highlandsniptechnology.com wrote:
On Mon, 11 Nov 2019 18:26:29 +0000, Clive Arthur
cliveta@nowaytoday.co.uk> wrote:

On 11/11/2019 15:48, dagmargoodboat@yahoo.com wrote:

snipped

Idea #2 - A search for "multi-chip series green LED" gets lots of
results, e.g.

Power LEDs made with series die--

https://www.cree.com/led-components/products/xlamp-leds-arrays/xlamp-mc-e



Only white or RGB as far as I can see?

Cheers

Digikey has 12 and 24 volt blue LEDs

https://www.digikey.com/products/en/optoelectronics/led-lighting-color/125?FV=-8%7C125%2C37%7C320441%2C37%7C320579&quantity=0&ColumnSort=-319&page=1&pageSize=25


Look for "lighting" LEDs.

I looked at one of these and it's Parallel LEDs with a driver of some
sort as far as I can tell.

https://static.rapidonline.com/pdf/55-2602_v1.pdf

One of these (although overkill in other respects) looks to me like it
could be subverted to do what you wanted. Maybe even put the receiver
LEDs in series to get plenty of extra voltage at the other end.

White ones in series configuration are easier to find cheaper:
https://static.rapidonline.com/pdf/500235_v1.pdf

--
Regards,
Martin Brown

 

[Winfield Hill]

Clive Arthur wrote...

An old abandoned requirement has re-surfaced...

If I wanted to use some series LEDs, illuminated by
more LEDs to generate a small amount of isolated power
- say to turn on a MOSFET not particularly quickly,
say 10V at a few uA - what would be the best type?

[I can't use the packaged photovoltaic
isolators/drivers, I need a bit more distance.]

In AoE3, page 205, we have Figure 3.107, where we show
and discuss the scene you're talking about. We used a
TLP191B as an isolated voltage source. Comes in a small
4-pin pkg, $1.71, qty 100, at Digi-Key. It's rated for
5kV isolation for 1 minute, call it 2kV continuous. It
provides 7V with a 10uA load, driving its LED with 10mA
(we suggest 30mA drive to get 8V out). This compares to
10V at 2uA load, in your final blue-to-green LED setup.

You said you need more distance, a few mm, is that for
a higher voltage rating? What rating do you need, and
what do you think your LED-pair setup will be good for?

BTW, I assume you read our AoE x-Chapter, section 9x.23,
posted here earlier? Sending Power on a Beam of Light

https://www.dropbox.com/s/xj5hewvisdo7ai4/9x.23_light-power.pdf?dl=1


--
Thanks,
- Win

 

[John Larkin]

On Mon, 11 Nov 2019 19:34:21 -0800 (PST), dagmargoodboat@yahoo.com
wrote:

On Monday, November 11, 2019 at 1:18:13 PM UTC-5, John Larkin wrote:
On Mon, 11 Nov 2019 07:48:17 -0800 (PST), dagmargoodboat@yahoo.com
wrote:

On Monday, November 11, 2019 at 7:48:37 AM UTC-5, Clive Arthur wrote:
I did some crude testing with Red, Green, Blue and UV LEDs.

All 1210 SMD 'high brightness' types from the same supplier.

One of each in series at their rated 20mA, then holding another of each
against each in turn, no air gap, switching in 1M as a load.

First thing to notice is how much brighter the green appears to be, yes
I know that's where the eye is most sensitive, but it does stand out
more than I expected. The red and blue appear about the same brightness
as each other, the UV emits a little visible violet.

Volts OC/Volts 1M load (OC is DVM impedance)

Receive -> Red Green Blue UV
Tx
Red 1.53/1.50 3m/0 0/0 0/0
Green 1.59/1.58 2.03/1.15 200m/20m 3m/2m
Blue 1.50/1.45 2.12/2.11 2.29/1.90 9m/2m
UV 1.42/63m 2.11/2.09 2.34/2.29 2.61/2.47

So Blue --> Green looks favourite, no better than UV --> Green but
easier to see.

If TX is longer wavelength than RX then nothing much, if TX is
considerably shorter than RX then weak. Best seems when TX is a little
shorter than RX as predicted by Martin Brown.

So five Green receivers gives me my 10V. Five Blue transmitters may
work with a gap, may need focussing, could use more powerful types.

Cheers
--
Clive

Idea #1 - right-angle SMD LED array
[ ] [ ]
| )~~> ( |
[ ] [ ]

[ ] [ ]
| )~~> ( |
[ ] [ ]

[ ] [ ]
| )~~> ( |
[ ] [ ]

[ ] [ ]
| )~~> ( |
[ ] [ ]

Idea #2 - A search for "multi-chip series green LED" gets lots of
results, e.g.

Power LEDs made with series die--
https://www.cree.com/led-components/products/xlamp-leds-arrays/xlamp-mc-e

3-in-series, custom, to your spec, for $4.50 per LED, 100 min.
https://lamptech.com/led/multi-chip-leds/build-your-own/

Idea #3 - If you've got lots of time, a simple 2-transistor relaxation
boost converter can boost 2V to 10V, allowing you to use just one LED
Tx-Rx pair instead of five.

Cheers,
James Arthur

There's an old circuit out there that uses an LED in PV mode to
collect power, to blink that same LED. Rather than that, Clive
could charge a cap up to a threshold, which fires a switch, that
charges an inductor. When the switch opens, the inductor flies
back.

It's almost easier to draw than describe, but I haven't the time
to ASCII it just now. Too busy.

I suppose one could square-wave modulate the transmitter LEDs and
somehowmumblemumble use the AC on the receive side. That would give a
bit more peak voltage at the receiver, for a given average transmit
drive.

Make a photovoltaic C-W! <grins

Cheers,
James Arthur

Endless goofy possibilities.

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[John Larkin]

On Tue, 12 Nov 2019 07:15:11 +0000, Clive Arthur
<cliveta@nowaytoday.co.uk> wrote:

On 12/11/2019 03:44, jlarkin@highlandsniptechnology.com wrote:
On Mon, 11 Nov 2019 18:26:29 +0000, Clive Arthur
cliveta@nowaytoday.co.uk> wrote:

On 11/11/2019 15:48, dagmargoodboat@yahoo.com wrote:

snipped

Idea #2 - A search for "multi-chip series green LED" gets lots of
results, e.g.

Power LEDs made with series die--
https://www.cree.com/led-components/products/xlamp-leds-arrays/xlamp-mc-e


Only white or RGB as far as I can see?

Cheers

Digikey has 12 and 24 volt blue LEDs

https://www.digikey.com/products/en/optoelectronics/led-lighting-color/125?FV=-8%7C125%2C37%7C320441%2C37%7C320579&quantity=0&ColumnSort=-319&page=1&pageSize=25

Look for "lighting" LEDs.



I looked at one of these and it's Parallel LEDs with a driver of some
sort as far as I can tell.

Cheers

I have some high-voltage LEDs that are just a bunch of die in series.

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[Winfield Hill]

Clive Arthur wrote...

It's a confidence thing. A few mm is clearly visible,
a visible LED likewise, and a physical gap means a
mechanical interlock is easy and visible.

Is this an educational thing?
What LED p/n did you end up with?


--
Thanks,
- Win

 

[Clive Arthur]

On 12/11/2019 12:45, Winfield Hill wrote:

Clive Arthur wrote...

An old abandoned requirement has re-surfaced...

If I wanted to use some series LEDs, illuminated by
more LEDs to generate a small amount of isolated power
- say to turn on a MOSFET not particularly quickly,
say 10V at a few uA - what would be the best type?

[I can't use the packaged photovoltaic
isolators/drivers, I need a bit more distance.]

In AoE3, page 205, we have Figure 3.107, where we show
and discuss the scene you're talking about. We used a
TLP191B as an isolated voltage source. Comes in a small
4-pin pkg, $1.71, qty 100, at Digi-Key. It's rated for
5kV isolation for 1 minute, call it 2kV continuous. It
provides 7V with a 10uA load, driving its LED with 10mA
(we suggest 30mA drive to get 8V out). This compares to
10V at 2uA load, in your final blue-to-green LED setup.

You said you need more distance, a few mm, is that for
a higher voltage rating? What rating do you need, and
what do you think your LED-pair setup will be good for?

BTW, I assume you read our AoE x-Chapter, section 9x.23,
posted here earlier? Sending Power on a Beam of Light

https://www.dropbox.com/s/xj5hewvisdo7ai4/9x.23_light-power.pdf?dl=1

It's a confidence thing. A few mm is clearly visible, a visible LED
likewise, and a physical gap means a mechanical interlock is easy and
visible.

If someone is going to handle a device which is normally powered form
1kV or so, then these things are more comforting than a small plastic
package, no matter what the specs.

I've used the photovoltaic devices elsewhere, they're very useful. I'm
aiming for 10V 10uA or so and don't much care about efficiency. I'm
going to try some narrow beam LEDs next, but not for a few days.


Cheers
--
Clive

 

[Clive Arthur]

On 12/11/2019 20:23, Winfield Hill wrote:

Clive Arthur wrote...

It's a confidence thing. A few mm is clearly visible,
a visible LED likewise, and a physical gap means a
mechanical interlock is easy and visible.

Is this an educational thing?
What LED p/n did you end up with?


Not edumicational. It's on hold for a few days thanks to pesky customers.

Cheers
--
Clive

 

[Martin Brown]

On 13/11/2019 10:25, Chris Jones wrote:

On 13/11/2019 07:07, Clive Arthur wrote:
On 12/11/2019 12:45, Winfield Hill wrote:
Clive Arthur wrote...

An old abandoned requirement has re-surfaced...

If I wanted to use some series LEDs, illuminated by
more LEDs to generate a small amount of isolated power
- say to turn on a MOSFET not particularly quickly,
say 10V at a few uA - what would be the best type?

[I can't use the packaged photovoltaic
isolators/drivers, I need a bit more distance.]

[snip]
  You said you need more distance, a few mm, is that for
  a higher voltage rating?  What rating do you need, and
  what do you think your LED-pair setup will be good for?

  BTW, I assume you read our AoE x-Chapter, section 9x.23,
  posted here earlier?   Sending Power on a Beam of Light

https://www.dropbox.com/s/xj5hewvisdo7ai4/9x.23_light-power.pdf?dl=1


It's a confidence thing.  A few mm is clearly visible, a visible LED
likewise, and a physical gap means a mechanical interlock is easy and
visible.

If you are relying on a mechanical shutter as the interlock, you'd have
to make sure that that the output LEDs acting as PV devices never get to
be in sunshine, or the output will be powered whether or not the
interlock is engaged. It might be tricky to make the interlock visible
and keep the PV devices reasonably in the dark, both at the same time.

I wouldn't fancy relying on an optoelectronic HT safety interlock. The
only HT interlock I trust is a grounding strap to a known good earth.

--
Regards,
Martin Brown

 

[Chris Jones]

On 13/11/2019 07:07, Clive Arthur wrote:

On 12/11/2019 12:45, Winfield Hill wrote:
Clive Arthur wrote...

An old abandoned requirement has re-surfaced...

If I wanted to use some series LEDs, illuminated by
more LEDs to generate a small amount of isolated power
- say to turn on a MOSFET not particularly quickly,
say 10V at a few uA - what would be the best type?

[I can't use the packaged photovoltaic
isolators/drivers, I need a bit more distance.]

  In AoE3, page 205, we have Figure 3.107, where we show
  and discuss the scene you're talking about.  We used a
  TLP191B as an isolated voltage source.  Comes in a small
  4-pin pkg, $1.71, qty 100, at Digi-Key.  It's rated for
  5kV isolation for 1 minute, call it 2kV continuous.  It
  provides 7V with a 10uA load, driving its LED with 10mA
  (we suggest 30mA drive to get 8V out).  This compares to
  10V at 2uA load, in your final blue-to-green LED setup.

  You said you need more distance, a few mm, is that for
  a higher voltage rating?  What rating do you need, and
  what do you think your LED-pair setup will be good for?

  BTW, I assume you read our AoE x-Chapter, section 9x.23,
  posted here earlier?   Sending Power on a Beam of Light

https://www.dropbox.com/s/xj5hewvisdo7ai4/9x.23_light-power.pdf?dl=1


It's a confidence thing.  A few mm is clearly visible, a visible LED
likewise, and a physical gap means a mechanical interlock is easy and
visible.

If you are relying on a mechanical shutter as the interlock, you'd have
to make sure that that the output LEDs acting as PV devices never get to
be in sunshine, or the output will be powered whether or not the
interlock is engaged. It might be tricky to make the interlock visible
and keep the PV devices reasonably in the dark, both at the same time.

 

[John Larkin]

On Wed, 13 Nov 2019 16:16:50 -0800 (PST), dagmargoodboat@yahoo.com
wrote:

On Wednesday, November 13, 2019 at 5:25:58 AM UTC-5, Chris Jones wrote:
On 13/11/2019 07:07, Clive Arthur wrote:
On 12/11/2019 12:45, Winfield Hill wrote:
Clive Arthur wrote...

An old abandoned requirement has re-surfaced...

If I wanted to use some series LEDs, illuminated by
more LEDs to generate a small amount of isolated power
- say to turn on a MOSFET not particularly quickly,
say 10V at a few uA - what would be the best type?

[I can't use the packaged photovoltaic
isolators/drivers, I need a bit more distance.]

  In AoE3, page 205, we have Figure 3.107, where we show
  and discuss the scene you're talking about.  We used a
  TLP191B as an isolated voltage source.  Comes in a small
  4-pin pkg, $1.71, qty 100, at Digi-Key.  It's rated for
  5kV isolation for 1 minute, call it 2kV continuous.  It
  provides 7V with a 10uA load, driving its LED with 10mA
  (we suggest 30mA drive to get 8V out).  This compares to
  10V at 2uA load, in your final blue-to-green LED setup.

  You said you need more distance, a few mm, is that for
  a higher voltage rating?  What rating do you need, and
  what do you think your LED-pair setup will be good for?

  BTW, I assume you read our AoE x-Chapter, section 9x.23,
  posted here earlier?   Sending Power on a Beam of Light

https://www.dropbox.com/s/xj5hewvisdo7ai4/9x.23_light-power.pdf?dl=1


It's a confidence thing.  A few mm is clearly visible, a visible LED
likewise, and a physical gap means a mechanical interlock is easy and
visible.

If you are relying on a mechanical shutter as the interlock, you'd have
to make sure that that the output LEDs acting as PV devices never get to
be in sunshine, or the output will be powered whether or not the
interlock is engaged. It might be tricky to make the interlock visible
and keep the PV devices reasonably in the dark, both at the same time.

True.

This level-shifter --> doubler has 0VDC output under static
illumination, 8V when illumination is alternated between LED1 and LED2.

C1 C3 D4
.-----+-----||-----+------------+-----||-----+---->|----+---
LED1 | | | | | |
~> V --- --- D2 V --- --- C4
--- ~>^ LED2 D1 ^ --- D3 ^ ---
| | | C2 | | |
=== === .---+-----||-----+------------' ===
|
===

LED1 = LED2 = green
D1-4 = BAT54

Cheers,
James Arthur

Back-to-back PV led's is cute. Add a discharge resistor to turn off
his mosfet.

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

On Wednesday, November 13, 2019 at 5:25:58 AM UTC-5, Chris Jones wrote:

On 13/11/2019 07:07, Clive Arthur wrote:
On 12/11/2019 12:45, Winfield Hill wrote:
Clive Arthur wrote...

An old abandoned requirement has re-surfaced...

If I wanted to use some series LEDs, illuminated by
more LEDs to generate a small amount of isolated power
- say to turn on a MOSFET not particularly quickly,
say 10V at a few uA - what would be the best type?

[I can't use the packaged photovoltaic
isolators/drivers, I need a bit more distance.]

  In AoE3, page 205, we have Figure 3.107, where we show
  and discuss the scene you're talking about.  We used a
  TLP191B as an isolated voltage source.  Comes in a small
  4-pin pkg, $1.71, qty 100, at Digi-Key.  It's rated for
  5kV isolation for 1 minute, call it 2kV continuous.  It
  provides 7V with a 10uA load, driving its LED with 10mA
  (we suggest 30mA drive to get 8V out).  This compares to
  10V at 2uA load, in your final blue-to-green LED setup.

  You said you need more distance, a few mm, is that for
  a higher voltage rating?  What rating do you need, and
  what do you think your LED-pair setup will be good for?

  BTW, I assume you read our AoE x-Chapter, section 9x.23,
  posted here earlier?   Sending Power on a Beam of Light

https://www.dropbox.com/s/xj5hewvisdo7ai4/9x.23_light-power.pdf?dl=1


It's a confidence thing.  A few mm is clearly visible, a visible LED
likewise, and a physical gap means a mechanical interlock is easy and
visible.

If you are relying on a mechanical shutter as the interlock, you'd have
to make sure that that the output LEDs acting as PV devices never get to
be in sunshine, or the output will be powered whether or not the
interlock is engaged. It might be tricky to make the interlock visible
and keep the PV devices reasonably in the dark, both at the same time.

True.

This level-shifter --> doubler has 0VDC output under static
illumination, 8V when illumination is alternated between LED1 and LED2.

C1 C3 D4
.-----+-----||-----+------------+-----||-----+---->|----+--->
LED1 | | | | | |
~> V --- --- D2 V --- --- C4
--- ~>^ LED2 D1 ^ --- D3 ^ ---
| | | C2 | | |
=== === .---+-----||-----+------------' == |
==
LED1 = LED2 = green
D1-4 = BAT54

Cheers,
James Arthur