www.robowars.org

RoboWars Australia Forum Index -> Technical Chat

LED recommendations


Post new topic   Reply to topic
  Author    Thread
Glen
Experienced Roboteer


Joined: 16 Jun 2004
Posts: 9481
Location: Where you least expect


 Reply with quote  
LED recommendations

hello,

i keep blowing up LEDs on an almost monthly basis and its getting a bit old now..

ive been using a bezel mount 12v LED (comes with its own inbuilt resistor)
and i had them wired up into the main power system in screwy, cobra 1, and for the last 3 events with the recent cobra.

last event i had it wired off the IBC and once more its blown up.

can anyone recommend a bezel mount LED that WONT explode.

any help appreciated, thanks

Post Sun Jun 27, 2004 5:57 pm 
 View user's profile Send private message Send e-mail Visit poster's website MSN Messenger
Spockie-Tech
Site Admin


Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia


 Reply with quote  

how the hell are you making LEDs explode ? Shocked

If you have the correct current limiting resistor in series with them (or just use the 12v ones from Bursons that have them built in), then it should be impossible to get enough current through them to make them go bang.

Even if you ran a 12v-resistored led on 24v, thats still only 40ma.. shouldnt be enough to cause bangs.. you're not getting big nasty spikes from your motors through them or anything are you ?

Any more info ?

Post Sun Jun 27, 2004 6:10 pm 
 View user's profile Send private message Send e-mail Visit poster's website MSN Messenger
Glen
Experienced Roboteer


Joined: 16 Jun 2004
Posts: 9481
Location: Where you least expect


 Reply with quote  

yeah these ones have little resistors already built into them.

at the moment ive got the LEDs wired to the IBC's ground and 12v+ output.

these are the ones im using. jeff f. suggested they are globes, but having a look inside they really look like LEDs with soldered on resistors

http://www1.jaycar.com.au/productView.asp?ID=SL2642&CATID=21&keywords=&SPECIAL=&form=CAT&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=402

at marayong 6 it worked fine until scrap really hit it hard and it clicked off, in the second fight el bravo hit it again and turned it back on and then it went off again. in the final it was off until a hit on singularity caused it to go off again. i tested it on a battery and it wont turn on.

maybe the connections onto the IBC i did are really crappy and the shaky supply is making them blow?

im thinking the impacts wrecked them, so im going to crack one open and test the bare LED without the resistor and see what that accomplishes.[/url]

Post Sun Jun 27, 2004 7:50 pm 
 View user's profile Send private message Send e-mail Visit poster's website MSN Messenger
Spockie-Tech
Site Admin


Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia


 Reply with quote  

I'm betting thats a lamp, as in a filament globe sealed inside that plastic.

LEDs are practically impact proof (well, dont hit with them with a hammer), but any amount of indirect shock shouldnt bother them at all, they just dont blow from mechanical shocks. Also, most of Jaycars Leds have a part number that starts with Z, thats an SL, which I'm betting stands for sealed lamp or something like that.

lastly, if you have a digital multimeter, pop it in ohms mode and measure the resistance across a known working one (if you have any left, else get the jaycar store guys to do it for you). If you show *any* resistance at all, other than open-circuit, then its most likely a lamp. Leds are semiconductors and dont conduct at all until you reach their breakover-voltage, which most multimeters wont in ohms mode. If its a globe, it will most likely show some fairly low ohms being the filament resistance.

If you want a suitable LED for a power indicator, go to a Bursons Auto-Parts (if you have them in sydney, otherwise Repco I think), and look for a large diameter chrome bezel mounted LED indicator. They come in Red and Green and are double the size of your usual LED. They have built in resistors for 12v, and I think from memory are a standard NARVA brand part.

Post Sun Jun 27, 2004 8:33 pm 
 View user's profile Send private message Send e-mail Visit poster's website MSN Messenger
colin



Joined: 16 Jun 2004
Posts: 102


 Reply with quote  

I could be wrong on this... if you had a variable power supply and turned it up slowly if its a light it should grow bright, if its LED it won't work and then very quickly it will brighten up.

also reading the description: Red, sealed, ideal for cars as an indicator for driving lights, etc.- Also suitable for burglar alarms.- Panel cut out 10mm.- Rectangular lens 12 x 20mm.- Length 45mm.

I'm seeing nothing that says its an LED, so i expect its a 12v light globe

Post Sun Jun 27, 2004 11:41 pm 
 View user's profile Send private message
Simo



Joined: 28 Jun 2004
Posts: 1


 Reply with quote  

Hello Glen,

Unfortunatelly that one is a lamp type and not LED.

Jaycar do have a 12v Panel-mount LED, Cat no: SL-2644 (Page 368 of 2004 Cat, or HERE ), but it won't fit in the same cutout and only has a 3mm LED.

If you want a larger 5mm one, they have these too but still won't fit on the cutout and only in a 2v version, a 470 ohm (Yellow/Voilet/Brown/Gold) resistor in series will allow use with 12 volts.

Altronics and DSE have panel-mount LEDS too.

Farnell have some with 8mm LED's (14mm head dia) that you can shove into the cutout after drilling it out to 12.3mm(1/2"), they are 2v, and a little pricey(normal for Farnell) at $6.75 ex GST, Order Code: 313-4325

RS have some plastic snap-in bezel LED's with 10mm lens, 16mm head and 14mm mounting hole that work with 12v and available at their trade counters(if there's one nearby), Cat: 355-6865 $2.54 ea plus GST

Good luck Smile
Simon

Post Mon Jun 28, 2004 9:15 pm 
 View user's profile Send private message
  Display posts from previous:      

Forum Jump:
Jump to:  

Post new topic   Reply to topic
Page 1 of 1


Forum Rules:
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum

 

Last Thread | Next Thread  >
Powered by phpBB: © 2001 phpBB Group
millenniumFalcon Template By Vereor.