Laser Christmas outdoor projectors..

HI All I was prompted to investigate these - we like to illuminate the outside (& inside!) of the house, and these looked like a good idea. The one I purchased allegedly had two lasers (red & green) and four different effects. Trouble is - this one seems to be faulty - the ebay seller has refunded my money (bless 'em). The unit has a waterproof momentary push-button on the back, it seems to need a press in order to start the thing working - which is kind of inconvenient as our outdoor lights are usually on a timer, and, even if this unit was working properly, I can't see me nipping outside every night just to push the button! Just wondering if anybody else has one of these new-fangled units - and whether theirs starts automatically when mains is switched on, or if it's a elfin-safety feature of the unit that it requires a digit on the button to start the lasers? The very thin user manual also says that the unit needs to be switched 'off' to cool down for 30 minutes after 5 hours of running... this particular unit doesn't run for more than a minute or so before cutting out, so it's kind of academic Any real-life experiences, please? Thanks Adrian

Reply to
Adrian Brentnall
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I seem to remember a discussion hereabouts concerning the illegality of the lasers in these or similar units. Maybe somebody who took part in that thread might come along shortly.

Reply to
Davey

That sounds a bit naff. I wonder if there are any of the stage devices going second hand. Even back in the 80s some of these seemed to be able to run all the time with little issues out of dooors and in the rain, at least when I could see back then raindrops and lasers made for a very interesting almost strobe droplets slow motion effect. Brian

Reply to
Brian Gaff

HI Brian Yes - something's not right somewhere After sitting in my (cold) outdoors workshop overnight, the laser decided that it would work... but only for about 5 minutes.. then it stopped! Could be the power-supply overheating, I guess - toying with the idea of feeding it 5v from a.n.other psu - but not sure I can really be bothered As I say - the seller refunded me in full, so the device owes me nothing, - but that little 'engineer' voice keeps saying "perhaps it's an easy fix" - but, against that, I don't really want to be fiddling about with lasers when I'm not sure what I'm doing - and I've plenty of other fruitless-but-engaging jobs to spend my time on. Adrian

Reply to
Adrian Brentnall

I don't mind a house going full chav, ie covered with illuminations: the owner has made an effort and even if I don't like it personally, I expect the local kids love it.

It's "half chav" that's horrid - one manky illuminated Rudolph dangling from the gutters...

Reply to
Tim Watts

Love the "Half Chav" term. But could be a potential "Full Chav" in a few years.

Reply to
DerbyBorn

... in March.

Owain

Reply to
spuorgelgoog

I have just bought such a beast with the intention of it being switched on tonight and left on for a few hours for the first time. I bought mine from TLC along with a few extra Icicle connectable sets.

No limitations of use in the instructions.

Mike

Reply to
Muddymike

I'd be interested to hear how you get on.

This one is branded "Christmas Workshop" and is item no 89180...

Even if it had worked for more than a few minutes, the need to trot outside and press a button to start it up, rather than just turning on the mains to it, would have been a bit of a pain.

It also has a photocell in the business end of the projector, that stops the thing from running unless it's "dark enough" - but doesn't seem to allow it to run again the next time it gets "dark enough" (like the following night... Seems to have been thought out oddly... or maybe not at all?

Adrian

Reply to
Adrian Brentnall

"Christmas Workshop" is a brand name of Ben Ross, who are one of the el-cheapo importers.

Kind regards

Mike

Reply to
Muddymike

HI Mike Yes - I found that out already - that's where the trail went dead... Not going to be a lot of 'tech support' available from them, then.. Thanks Adrian

Reply to
Adrian Brentnall

A surfet of static and/or random flashing lights is naff, full stop. If you are going to do it do it properly, set and timed to music:

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How to... but uses pixel LEDS.

Currently have a Pi Zero directly controlling three short strings (4 ordinary bright white LEDs/string salavged from a cheap decoration SWMBO'd didn't like) with PWM and transistor switch per string. I might see what the current draw of the outdoor LED lights we normally use is and hack off the basic controller and replace it with a Pi to give sequences and effects that we like.

Using pixel LEDs seems cheating some how, but simple LED strings can't do what they can do.

Reply to
Dave Liquorice

Bloody hell! That's doing it properly!

All he needs is a couple of musical giant tesla coils to finish that (and see off the burglars).

I thought he'd be doing something like that.

He says he's using the: WS2811 - you can get RGB LEDs with that integrated to even avoid the need for a PCB (or at least all it would do is act as mounting and a wire carrier). I suspect his setup predates that LED, maybe - but if anyone wants to try this, the WS2812B LED works in the same way - and you can buy them mounted on tape (from the USA) for reasonable coin).

I wonder why all the crazy good stuff like this is always an american?

Reply to
Tim Watts

I just watched another of Matt Johnson's videos and it seems he buys the "pixels" (individual light unit) ready made from a dude on Guanzhong via Aliexpress.

That makes it seem much more doable - I was thinking "how did he get the time to make 1000's of lights and wire them up...

Reply to
Tim Watts

Last year I added a PCB with 8 LED pixels to an aliexpress order, just to see how easy they are to drive.

I found they were easy enough to drive from a USB->serial adapter (admittedly a specialised one that can do sync as well as async) and knocked up a little python program to run through a few effects, so I bought a 200 pixel length of LED tape as part of another aliexpress order ... now's probably the time to dig them out.

Reply to
Andy Burns

This is the supplier the bloke in the video used:

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How can it be so cheap?

Anyway - I feel some fun coming on next Xmas :)

Nothing like Matt's - probably just a tree in the garden, or the edges of the front of the house of something.

I think those chips drive the same way as the Pi's Unicorn Hat (latter uses the LEDs with the built in chip rather than the external one, but given the basic drive is the same (the whole string is a giant D-shift latch register with D-in and D-out on each lamp - I suspect the protocol is the same.

A Pi can drive one such data line directly using one of the DMA controlled pulse shaping IO pins - but you usually need a level shifter to gi from 5V to 12V for the lamps.

So in theory, if you can devote one Pi to a string, the Unicorn Hat library should do the job - I've played with that and it's dead easy.

In a way, it might make the setup easier to use 1 Pi per string - write a super simple daemon that sits on Wifi and accepts various pattern requests and plays them out to the string.

At that point, you could even run the string and Pi in a weatherproof box off a car battery (obviously with a 5V regulator for the Pi). It would make the temporary installation even easier that Matt's.

Reply to
Tim Watts

Yes, pretty cheap, can't remember what I paid last year (Chinese new year discounts).

You drive them with varying width pulses (long high followed by short low is a "1", short high followed by long low is a "0") each pixel re-clocks the output to the next in the chain.

Timing is quite tight to within about 150ns, the adafruit library does it by setting a 6MHz clock, and using a whole byte of 0b11111000 for the "1" or 0b11100000 for the "0" pulse, so each RGB triplet takes 24 bytes to send the 24 pulses per pixel, the USB block transfer size means this is limited to about 340 pixels.

I realised I could set the clock to 2.4MHz on my USB dongle and just send three bits per pulse either 0b110 for "1" or ob100 for "0" so just

8 bytes per RGB triplet, theoretically I could run 2400 pixels and the timing works out closer to the ideal pulse width.

My strips are 5V powered, but I still need a 3.3->5.0 level shifter for the clock signal.

For now I just run the python script on a netbook, hooked by USB to the sync converter, in fact I was powering the small strip of 8 pixels from the USB too. I found all the various components and hooked them back together, found I could power 24 pixels of my longer strip, any more than that sagged the voltage so much it started "crashing" the pixels i.e. they weren't clocking and re-sending the data reliably.

So I need to dig out a 5V 3A PSU to power the LEDs not from the USB, then I can work on some more impressive patterns for the full strip.

Fun stuff.

Reply to
Andy Burns

Nice move :)

Sorry - yes. You're right. I forgot the Pi's GPIO were at 3.3V.

Reply to
Tim Watts

I was going to add, before my finger hit send - I wonder how long a strip you could run before the data line gets too corrupted. 100 on cable (I'm guessing 10m?) seems find - but I wonder how much longer you could go, assuming sufficient 5V/12V power.

Reply to
Tim Watts

I think there's no absolute limit, my strip of 144 (not 200 like I though) takes 75mA for the inbuilt chips with all pixels off.

Each pixel regenerates a clean version of the pulse-train to its neighbour, in my case the limit is the USB block size, once you hit that you would get a long enough gap in the pulses that the pixels at the "head" of the chain would start listening for new colours, rather then silently echoing them down the line, which is how you start a new "frame".

Reply to
Andy Burns

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