Hi folks,

Been looking round for Infinity lights screens/Time tunnel screens which were popular back in the 80's. Surprised to see they are still made, but I can only find them at about 800mm square. I want something a bit bigger.

I thought about making one, but cant find any info on the internet as to how they are made. Has anybody had one apart to give me a clue how they are built?

Im guessing one way mirror (acrylic) as the front screen. Bulbs round the edge. Im just not sure if it is a flat mirror at the back, or a convex mirror?

Are they as simple as that?

Any info gratefully received.

Thanks

Andy

Ordinary mirror at the back, 2 way mirror on the front, reflective side facing the ordinary mirror...then lights inbetween.

The availability of tiny hyper-bright LEDs gives you a few new options.

Mirrored car window coating from Halfords etc could come in handy for this, then you'd only need clear perspex. It would aslo be a lot lighter to carry than 2 mirrors

Thank you both for your replies. I have contacted a local plastics supplier who has a wide range of acrylic mirror sheeting and acrylic one way sheeting.

I thought xmas lights would be the easiest option, but LEDs look a better option because they will withstand mobile use better than bulbs.

I read somewhere it is possible to run LEDs direct off the mains without using a transformer. I think one method is to use a dropping resistor, but when used with many LEDs you need high wattage resistors, and they generate a fair bit of heat. Another method is to use capacitors which dont have the heat problems of using resistors. I have searched the Internet, but cant find any descriptions of this method, or any circuit diagrams.

Am I making this more complicated than I need? Any Advice!

Thanks
Andy

I fancy a go at this as I was goin to have a go at a light screen anyway.

Good idea Steve Halfords

Halfords and B&Q im on my way (I will ask for a left handed screwdriver while im there )

What ever the outcome i will put pictuers on here to show all and see what you all think

Just to echo what Kingy has said. If you are going to play around with LED's then do it using a step down power supply which reduces the voltage to a relatively safe 6 or 12v dc.

Even at 6 / 12v you will need to use a resistor with a value derived from calculating the LED's forward voltage and current, otherwise you will damage the led or shorten it's life from over-driving. Of course you can also do this by wiring the LED's in series, but again you need to work this out correctly.

You should never use resistors or diodes to drop the mains supply directly, even though this will drop the voltage, if the load current drops (ie an led fails or a wire breaks) then the low voltage side of the circuitry would rise to mains potential- delivering a potentially lethal shock risk. Using a transformer, gives isolation between the primary (mains) and secondary (low voltage) and is the safest way of dropping the voltage.

You can buy mains powered LED clusters to directly replace 'R' series reflector and PAR type lamps, and these are perfectly safe to use provided they are used as directed and not modified.

Did anyone else have the FAL time tunnels back in the early 80s? I had a round one and one with "Dancers" in it. Cant remember if it was round or square. Mine both had built in sound to light units. Cracking, cant remember what happened to them! ( well at the time.....)

Thanks for all the advice so far. I guess like most people here, I am confident in my knowledge of working with mains voltage, but I'm pushing it trying to run LEDs directly of the mains. When I wrote last time, I mentioned some articles I had read, but couldnt find them. I have searched again, and this is the article about running a LED on mains voltage using a capacitor and rectifier. I dont intend to take this route, but it maybe of interest to some of you.
http://www.marcspages.co.uk/tech/6103.htm

Somebody asked about the prices of sheet material I was quoted locally.

Clear acrylic which one way film can be applied:-
8x4 3mm £102.62 water clear acrylic
8x4 3mm £45.53 extruded clear acrylic

I was told the water clear acrylic was like glass, and the lower cost extruded acrylic was not as clear and may have imperfections, but would probably work for what I wanted.

8x4 3mm 95.64 mirror acrylic
Standard acrylic mirror sheets (not one way)

So about £150 + wood + trimming. But that would make 2 4x4 light screens.
The commercial ones I have seen are 402mmx402mm for £53.20 from www.terralec.com (hope im ok giving web address), Im not advertising for them, or recommending them, its the only place I found them for sale.

Thanks again for the advice and I may make a start on this little project in the next week or two. I will report on my results and put some pictures up.

Thanks again everyone
Andy

Running LEDs off transformers requires a rectifier, and if you dont want them to flicker you'll need a smoothing capacitor as well, not to mention a safe enclosure and fusing. If you want the cheapest, safest method, why not buy a mini switch-mode power supply like the sort they use for digital cameras and laptops? They come in all manner of voltages and current ratings and beefy ones are available for 10-20 quid, double insulated, regulated against voltage & load fluctuation and compact as you like.

You're best putting several LED's in series without a dropper resistor, adding up the Forward Voltage Drop until you reach the power supply level. Red, green and yellow LEDS require around 1.8-2V each at around 10-30mA, make sure they're all the same type for series use. Blue & White LED's require between 3-4V each so you can only connect a few in series. When you've got a series array, make some more and connect the arrays in parallel across your PSU keeping an eye on the total current so it doesnt overload it.

This is the industry standard way for LED arrays, eg inside Dance Floor Modules, LED Par Cans and LCD Backlight panels. Series means they each get the same current so they all light at the same intensity; no energy is wasted through resistors. The alternative is each LED connected in series with it's own resistor, this would be tedious to assemble if you have loads of LEDs to put in!

Most suppliers eg Maplin, RS etc have the forward voltage drop (Vf) and Typical Current (If.nom) ratings in the catalogue.

You can also of course buy ready made 'bulbs' made from LEDs as mentioned (clusters) but you'd have to sell your car to afford a boxfull.