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Large Led display

dr pepper

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My boss has asked me if I can make a speed indicator for people driving too fast on the premises.
I've put together a simple Hb100 radar sensor and a 'duino, it works well.
Now for the display, I want something 14 segment and 4 to 6" tall character height, I'd like to be lazy and buy a pre built weatherproof display unit, maybe with serial control.
Such things dont seem that common.
 

gary350

Well-Known Member
I can't help you with the radar but I can tell you how I build a speed read out 20 years ago. About 20 of us raced go-karts and we wanted to know how fast everyone was going. I used an industrial device from work that counts parts on the conveyor belt assembly line. This device sends a beam across the race track where a reflector sends the beams back to the receiver. There are 2 of these devices setting a 8 feet apart. When a go-kart breaks the first beam it starts a number counter that counts up 0 to 100. When second beam is broken it stops the counter and holds the number for a few seconds before it resets. My go kart use to stop the counter at 87 mph that was my top speed. You need to do the math to determine how far apart the beams need to be. Beams need to be exactly parallel. There is probably much better technology available today. The device I used did not count mph it counted in micro seconds.

Here is a picture of my go-kart it has a 4 cylinder 65 hp mercury outboard motor on it. Gear ratio 3.2 to 1. Water cooled with disc brakes.

gokart151_zpsf61491c8.jpg
 
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Ian Rogers

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I make a 4" 4 digit weatherproof display for fork truck... However i'm between units at the mo... London electronics do many large scale displays...

https://www.london-electronics.com/ This is where we bought them before I made mine...
 

ClydeCrashKop

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Can you weatherproof a PC monitor (industrial?) or an HDMI TV & a Raspberry Pi?
 

dr pepper

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I'll try london electronics.
Are you tax registered Mr Rogers?, your display might be what we want.
I dont really want to use a monitor or tv.
 

gophert

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I made this up for someone a while back.

It just take patience. Intensity was turned down to avoid saturating the camera. The hot spots were masked pretty well in real life - the camera is just easily saturated by the red LEDs when on full power.

Your coworkers would be pretty freaked out by these digits!

 

Ian Rogers

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Dear Dr.… I cannot make one at the moment.. No parts... No building.. Do you have strip board?.... I can send you my schematic... The box I use is from RS and I got a piece of window tint from Fleabay… The digits are around £6 each on RS for the 2" and £10 each for 4" ( knightbright ) I use ULN2803 or ULN2003 so I can have BIG digits.... Those displays are 10~12v .. The box is a Bopla BOCUBE with clear lid..

You'll soon see why they are expensive...… Mine has a pic12f1840 with auto shutdown RS232 connection...
 

Nigel Goodwin

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I made this up for someone a while back.

It just take patience. Intensity was turned down to avoid saturating the camera. The hot spots were masked pretty well in real life - the camera is just easily saturated by the red LEDs when on full power.

Your coworkers would be pretty freaked out by these digits!
I suspect I'm as sad as most people on here, but I really liked that :D

But I really loved the Predator films, I thought they were really well done, and that the invisibility was very believable.

How about some pictures round the back of the project?.
 

Tony Stewart

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It is trivial to make any size LED digits. get 12V LEDstrips and cut into segments then a 7 segment driver with for each segment using 1A Nch segment drivers and 5A Pch FET digit drivers. using 12V CD4000 logic. or whatever you can do better. Then adhere to black background . Boost to 14V if not right enough. Or use 5V RGB with SIO control. Then cover with Clear or diffused colored film from an art store if monochromatic.
 
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Tony Stewart

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If you need 16 Cd 5mm 30deg LEDs they will be 10x brighter than a stripLED at 20mA ea. I have a ton of surplus in WHite, Red Yellow
I also have 30 Cd. These are old specs. the Vf is now 3.15 +/-0.1 @20mA 16Cd~20Cd
ph # is obsolete.White LED Spec Sheet 2S-4000W30N16-5NFZ.png 1552837475049.png1552837516989.pngWhite LED Spec Sheet 2S-4000W30N16-5NFZ.png1552837475049.png1552837516989.png
 
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gophert

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I suspect I'm as sad as most people on here, but I really liked that :D

But I really loved the Predator films, I thought they were really well done, and that the invisibility was very believable.

How about some pictures round the back of the project?.

Whoa Nelly.

I honestly don't think I took any photos of the back (inside). I set that clock face that you see inside a box made of 3" wide strips of 12mm Baltic Birch - all painted black and key-hole cutouts in the back to hang it on the wall. I also had some air vent holes and speaker cutouts in the top/bottom 3" strips.

Everything was multiplexed across the four "digits" and controlled with a 18F46k80 (I just happened to have some on hand when I built it. Each segment on the digits are 3 high-brightness 5mm indicator LEDs wired in series and pushed in from the back with common cathode arrangement. All the LEDs were wired point-to-point on the back side. It looked like a rats nest and all connections were covered in hot glue to avoid any shorts and keep the LEDs in their mounting holes.

The most interesting / new thing was that all the audio beeps and final explosion sounds were made with the 18F chip. If I remember correctly, it had four different PWM outputs with independent duty cycle control and lots of PWM sweeps to randomly determined frequencies.p
 

Nigel Goodwin

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Whoa Nelly.

I honestly don't think I took any photos of the back (inside). I set that clock face that you see inside a box made of 3" wide strips of 12mm Baltic Birch - all painted black and key-hole cutouts in the back to hang it on the wall. I also had some air vent holes and speaker cutouts in the top/bottom 3" strips.
Well it looks really good, very impressive.

Everything was multiplexed across the four "digits" and controlled with a 18F46k80 (I just happened to have some on hand when I built it. Each segment on the digits are 3 high-brightness 5mm indicator LEDs wired in series and pushed in from the back with common cathode arrangement. All the LEDs were wired point-to-point on the back side. It looked like a rats nest and all connections were covered in hot glue to avoid any shorts and keep the LEDs in their mounting holes.

The most interesting / new thing was that all the audio beeps and final explosion sounds were made with the 18F chip. If I remember correctly, it had four different PWM outputs with independent duty cycle control and lots of PWM sweeps to randomly determined frequencies.p
Very nice.
 

Ian Rogers

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dr pepper

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I dont have time to assemble my own.
But I did find some 125 mm 7 segs from Rs, 25 quid, a pair of those might do.
Uln's would drive those, good idea.
 

ronsimpson

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Most Helpful Member
Years ago we made large signs with these. I call then "flip dots"
1553117789985.png
I have used what I call "flip segments" that work like the dots but look like the 7-segment displays. I can't find them now so they may have gone by-by.
1553118035234.png
 

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