LED Strips and power

[Gerwood Stewart]

Hi All

I have 4m of WS2812B leds, (60 per mtr) so about 240 leds.

I want to use them as overhead lighting in my garage, and likely on full brightness (or close to).

which by my calculation is about 15A draw (rounding up).

0.06A (at full power) * 240 = 14.4A 

I have a Pi Zero W with a python LED server that can control the lights easily ( I want to be able to turn the lights off without going to the shed, because I'm forgetful ).

If I chain the strips I'll have about 7 meters of wire, (1 meter strip across 4 beams). Data seems to be ok for that.

Power and data are independent and running across 7m the fall off in power to each LED is really noticeable. So I can run power separately to each strip, or to pairs of strips etc.

I have several different power supplies:

5v 40A

24v 15A

36v 6.7A

Split in two each strip should need about 7.5A

What would be the best approach for this?

[shykitten55]

I'm not a big expert on it, but I have played with those before.

I made a  project with a long string of them myself on an arduino.

I originally used 12v and dropped it to 5v via a regulator.

OUCH!   It got very hot - understandably.

If the LEDs take 5v, I would suggest using the 5v supply/unit.

If you don't, you will *waste* a lot of power dropping it from that voltage to 5v.

[Gerwood Stewart]

Thanks.

I'm not 100% on how Amps affects things.

I can do the conversion maths

But don't fully understand the impact of V or A on requirements.

If I have 5v 40Amp power supply, and the lights only need 15A is the extra going to cause any issues? (I.E. too much power, or is A only pulled as its used)?

Thanks

Gerwood

--
You received this message because you are subscribed to the Google Groups "Robots & Dinosaurs" group.
To unsubscribe from this group and stop receiving emails from it, send an email to sydney-hackspa...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/sydney-hackspace/a5d4de22-1b04-4721-a1f4-3f47d2283c5en%40googlegroups.com.

[Tomasz Mi]

Don't use a voltage linear regulator. They will just drop the voltage by turning the excess into heat. But buck converters should do a much better job. You can get them for less than 10 AUD.

--

[Julian Sortland]

Excess current availability is fine.  Individual supply wires to each strip will help, and this needs to be thick wire, to reduce voltage drops.

To view this discussion on the web visit https://groups.google.com/d/msgid/sydney-hackspace/CACGRv7TV22Ji2dAjWf%2B-a35csYvGUmWzvBNqcnXEaFYRnr30sw%40mail.gmail.com.

[Gerwood Stewart]

I've got 7.5A wire, that I was going to run to each set. It's just over the needed current if I split the lights into two groups for power (7.2A).

If I split each strip and give it, its own power, 3.6A and should be fine.

I was also going to put a 7A circuit breaker on each line (in a 2x2 configuration) and live with not being able to put the LEDS to full, full power.

G

To view this discussion on the web visit https://groups.google.com/d/msgid/sydney-hackspace/CAAC7N%2BfqeeRGAV-OEnDB9iT%2BKaQp69zBzmG3nrZ3ELi0%2BVfu9Q%40mail.gmail.com.

[Julian Sortland]

I am afraid that it is more complex than that (and I am home now, so can answer in depth).

"7.5 amp wire" just means it won't overheat and soften the insulation at this current.  This is suitable for a mains load which is not particularly sensitive to a voltage drop, provided the lead is not more than maybe 10 metres away (loop distance 20 metres).

However using the side below, and assuming a 6 metre distance to the 3.4 amp load, the voltage drop will be over a volt, or 20%, and thus the LEDs will be either dim, or the on-board logic will fail to operate.

https://www.jcalc.net/voltage-drop-calculator-as3008

The site suggests 4 or 6 square millimetre cable, depending on length.  The ones below are surprisingly affordable, and available by the metre.

https://lappaustralia.com.au/en/lapp-solar-cable-2x4mm-2-500

https://lappaustralia.com.au/en/lapp-solar-cable-2x6mm

You also should try to position the power supply so the cable length is as short as possible.  This would be in the garage, and you should probably put the Pi there too, with wires or wireless control from inside.

Also note that a fuse is not a current limiting device, it simply blows at some point, once its rated current is exceeded.  It would be fine to use a 10 amp fuse.

Julian.

====================================================
Julian Sortland, VK2YJS, AG6LE (VE).

Ph:  0429 470 672

61 Queen Street
OBERON  NSW  2787
AUSTRALIA

To view this discussion on the web visit https://groups.google.com/d/msgid/sydney-hackspace/CAOdMvxwYt2_p8gjx%2BPzMFbA7X1e%2B%2B15JUPW1_zECQUtQP1_YHA%40mail.gmail.com.

[Gerwood Stewart]

Thanks. I'll take a look at the wire.

The fuse/circuit breaker was there to be a circuit breaker and nothing, more, I wasn't expecting it to adjust the current.

I'll go read up some more on amps.

To view this discussion on the web visit https://groups.google.com/d/msgid/sydney-hackspace/CAAC7N%2Bdr8q4v-E3dB0PEbu3XSBMCkeCaac-hMZv2KAWtQuNnHg%40mail.gmail.com.

[Gerwood Stewart]

As an additional.

I've run the 1m strips off the 3.3v output on the pi and they work, but aren't as bright, so it probably can avoid some voltage drop, though I'd prefer the to be as small as possible

On Wed, 28 Jul 2021, 7:32 pm Julian Sortland, <vk2...@gmail.com> wrote:

To view this discussion on the web visit https://groups.google.com/d/msgid/sydney-hackspace/CAAC7N%2Bdr8q4v-E3dB0PEbu3XSBMCkeCaac-hMZv2KAWtQuNnHg%40mail.gmail.com.

[and...@arcadius.com.au]

If I were doing this...

1. Break the installation into short strings (1 meter? each)

2. Use a DC/DC converter with 5V output for each string, located at the string.

3. Use a 12V or 24V "bus" voltage (whatever the converter will handle for input) to each string

4. All the bus voltage feeds come back to a single point ("star configuration").

5. Send data from the RPi on separate output pins to each string. Gives a "star" data distribution.

6. Use a voltage level translator to lift the RPi data signals to 5V

7. RPi signal ground connects to the power ground star point

I have driven long strings of WS2812's and the power distribution is a bear, especially if you also have to daisy chain the data (which I did).

To view this discussion on the web visit https://groups.google.com/d/msgid/sydney-hackspace/CAOdMvxzRfjDDvrb-T7HmsVcr3UUK171_r290M5F0Oxc-3_izpA%40mail.gmail.com.

[Gerwood Stewart]

1. Break the installation into short strings (1 meter? each)

Ok. I was debating between string of 2 which becomes 2.8m (with the gap between them)

and individual 1m.

1m then

2. Use a DC/DC converter with 5V output for each string, located at the string.

Something like this? https://www.ebay.com.au/itm/392619758057

3. Use a 12V or 24V "bus" voltage (whatever the converter will handle for input) to each string

4. All the bus voltage feeds come back to a single point ("star configuration").

5. Send data from the RPi on separate output pins to each string. Gives a "star" data distribution.

I'm pretty sure my current setup relies on using the PWM pin (of which I think there is only one).

Does anyone have experience with LED strips on non-PWM pins?

6. Use a voltage level translator to lift the RPi data signals to 5V

7. RPi signal ground connects to the power ground star point

Thank you for the info.

To view this discussion on the web visit https://groups.google.com/d/msgid/sydney-hackspace/20210728033644.9d1a0d1db8c4b77c4298ce23ea964f3e.7f52231841.wbe%40email06.secureserver.net.

[Andrew Larkin]

60 leds per meter x 60mA each is 3.6Amp, so using that ebay module you would want to ensure you don't go to 100%.

You could go to a larger module that would do 2m of leds and put it in the middle - a "T" configuration.

Do you need to control all the LEDs individually? If not you can feed the same data to all the strings.

To view this discussion on the web visit https://groups.google.com/d/msgid/sydney-hackspace/CAOdMvxzvWhX23UBWxUJLfD2WA%3D6hRQP-6bysS4u_FLFU8ydCCg%40mail.gmail.com.

[Gerwood Stewart]

Great. Thank you

To view this discussion on the web visit https://groups.google.com/d/msgid/sydney-hackspace/61014016.1c69fb81.f4f49.f7dbSMTPIN_ADDED_MISSING%40gmr-mx.google.com.

[Kris]

could you save your addressable leds for another project and just use some 24v non addressable leds and a sonoff?

if all you're doing is turning them on and off this is much easier and much lower amps.

if you want a normal light switch as well, you could use a Shelly.

i reccomend these

https://www.sal.net.au/products/interior-led-lighting/led-strip-lights

they come with an (overrated) transformer, a plug. 3m adhesive and CRI over 90.

really nice light.

To view this discussion on the web visit https://groups.google.com/d/msgid/sydney-hackspace/CAOdMvxwYt2_p8gjx%2BPzMFbA7X1e%2B%2B15JUPW1_zECQUtQP1_YHA%40mail.gmail.com.

[Gerwood Stewart]

Now I know common sense is probably a good thing here... but ...

;)

I'm mostly putting to use stuff that I had lying around and want to put to a purpose.

I have a power supply (24v /15A), the controller already does what I want, and I'm not doing anything else with the LEDs for now, so I figure i might as well use them.

It seems what I need now is some buck converters and the right sized wire. Both things I now know more about. (Thank you everyone).

These also look great.

To view this discussion on the web visit https://groups.google.com/d/msgid/sydney-hackspace/dedfee21-caf7-ced5-859c-2a66a64dca97%40sleepingplanet.com.

[Madox]

Hi,

I have some experience with these LEDs :)  I've used them as room 'lighting' for over 5 years at the old apartment.  Some suggestions/queries

1) Are you SURE you want them as lighting?  Is it only to find stuff in the garage, not actually work in it right?  They may 'seem' bright but not really usable as work lights.

2) Instead of 'calculating' the power, I suggest you power the strip off a lab supply and check out how many amps it is drawing - my suspicion is that it is a lot lower than you think.  (SIGNIFICANTLY lower....)

3) Do you have diffusers handy for them?  I had mine installed in an aluminium channel with diffusers to make the individual LED's less noticeable and less harsh if you accidentally look up at them.

4) Also reconsider the 'all on', play around with the colours.  A warmer colour will seem almost just as bright and potentially use significantly less current.  (Again, this will lower that calculated number of yours down....)

Do share what you get it down to :)

// I have the same problem of wanting to use up stuff....

Cheers,

John

[Gerwood Stewart]

On Thu, 29 Jul 2021 at 23:31, Madox <mado...@gmail.com> wrote:

Hi,

I have some experience with these LEDs :)  I've used them as room 'lighting' for over 5 years at the old apartment.  Some suggestions/queries

1) Are you SURE you want them as lighting?  Is it only to find stuff in the garage, not actually work in it right?  They may 'seem' bright but not really usable as work lights.

I have two fluorescent (1.x meter)  lights in there already, there was a third, which took a beating from a garage door that came loose. I'm putting these where (around) that one was, so they don't need to light the whole space, just one section.

The space is 7x4m so they'll probably need to light about 2.5x4m (ignoring shelves etc). I want to know what the result is like. And I have some grand plan at some point, to try to make the shed 'off grid' and use 12v

2) Instead of 'calculating' the power, I suggest you power the strip off a lab supply and check out how many amps it is drawing - my suspicion is that it is a lot lower than you think.  (SIGNIFICANTLY lower....)

Yep. I deliberately went with full power because I don't know what colour temp, or level might work, and I wanted to at least start by turning them all on, and all up.

I have a cheap lab power supply somewhere, that I've been trying to locate so that I could

3) Do you have diffusers handy for them?  I had mine installed in an aluminium channel with diffusers to make the individual LED's less noticeable and less harsh if you accidentally look up at them.

No, that was something I noticed on the site Kris sent through.

https://www.sal.net.au/products/interior-led-lighting/led-strip-lights

I think after I've messed around with this and know what colour temp, and configuration I like, I'll remove all the fluorescents and put in LED strips. Probably from there.

4) Also reconsider the 'all on', play around with the colours.  A warmer colour will seem almost just as bright and potentially use significantly less current.  (Again, this will lower that calculated number of yours down....)

I wanted to start with white, or close to daylight and then try a warm colour and see the difference. I tend to prefer daylight in workspaces, such as the shed or the office, but once its dark enough I don't think it makes an enormous difference. During the day I find the current lights quite dim.

 

Do share what you get it down to :)

And I will, I have so far fallen short of buying a light meter to also check the brightness achieved between 3.3v and 5v, full vs lower etc.

Should anyone be interested, this is the lights running off 3.3v showing the voltage drop as each light gets progressively redder (from right to left, zig-zagging)

(And on a side note, I've just noticed, I'm flicking between british and 'merican spellings of things :\ )

 

// I have the same problem of wanting to use up stuff....

Cheers,

John

On Wednesday, 28 July 2021 at 1:53:49 pm UTC+10 ger...@gmail.com wrote:

Hi All

I have 4m of WS2812B leds, (60 per mtr) so about 240 leds.

I want to use them as overhead lighting in my garage, and likely on full brightness (or close to).

which by my calculation is about 15A draw (rounding up).

0.06A (at full power) * 240 = 14.4A 

I have a Pi Zero W with a python LED server that can control the lights easily ( I want to be able to turn the lights off without going to the shed, because I'm forgetful ).

If I chain the strips I'll have about 7 meters of wire, (1 meter strip across 4 beams). Data seems to be ok for that.

Power and data are independent and running across 7m the fall off in power to each LED is really noticeable. So I can run power separately to each strip, or to pairs of strips etc.

I have several different power supplies:

5v 40A

24v 15A

36v 6.7A

Split in two each strip should need about 7.5A

What would be the best approach for this?

--

You received this message because you are subscribed to the Google Groups "Robots & Dinosaurs" group.
To unsubscribe from this group and stop receiving emails from it, send an email to sydney-hackspa...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/sydney-hackspace/35b9d2a5-6d93-4fbc-9605-8ea4705cf3f0n%40googlegroups.com.

[Madox]

Snipped all the history

1) Re : Lux Meter

If you live near the space, I'm relatively close and can do an exercise run and leave it for pick-up at any nearby park...... OR

more interestingly for yourself and general interest to the list

https://core-electronics.com.au/piicodev-ambient-light-sensor-veml6030.html <-- Very very cheap value for money ambient light sensor that's apparently accurate to 10% of a calibrated lux meter (also have one in front of me, sitting on top of the lux meter...haven't validated the claim).

2) For reference, I had my 2M strip mounted using 3M command strips just on the side of the room.  From memory there was no noticeable dimming from one end to the other that's as pronounced when viewing 'yellow' (you do notice it with pure R,G,B).  Also from memory the entire strip was powered just from a 2or3A 5V wall wart...

At night I would only have literally 1 or 2 LED's on in 'Dim Red' (25%?) to provide enough illumination for my son to find his way to the toilet...

 

<snip>

[Gerwood Stewart]

Ooooh I like.

And unfortunately I am too far from the space, and more importantly I'm in Blacktown so I'm under pretty strict lockdown, but thank you.

On 3.3v and 1m I never noticed anything.

I remember seeing an LED lighting setup on Beyond 2000 once, where they hid them in the architraves and focused them at the ceiling to make it all bounce light.

I liked that approach

--

You received this message because you are subscribed to the Google Groups "Robots & Dinosaurs" group.
To unsubscribe from this group and stop receiving emails from it, send an email to sydney-hackspa...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/sydney-hackspace/c85de932-a5ff-45b7-9964-37176bb0ba5dn%40googlegroups.com.