"Help!" for: Electronics

[thatdecade]

You are burning out LEDs because your battery pack is overpowered for so few LEDs. By few, I mean under 50 LEDs...

You can continue using that 4xAA battery pack, but you must add 300 ohm resisters to each LED.

4x1.5V = 6V
6V / 20mA = 300 ohm

 

[Roku]

I also have a 1 battery pack for 1 AA but that didn't even light 1 LED.

Thank you for your reply i'll have drop by the mall and pick up some resisters
Edit: Quick question, Do i connect the resisters to the positive or negative ?

 

[Revenant1988]

I also have a 1 battery pack for 1 AA but that didn't even light 1 LED.

Thank you for your reply i'll have drop by the mall and pick up some resisters
Edit: Quick question, Do i connect the resisters to the positive or negative ?

1 AA is not enough voltage to power most LEDs. A single aaa or aa battery is only worth 1.5v. For pre-wired battery packs that voltage increases with each battery, so if you have a 3 AA pack its 1.5v x 3 = 4.5v. That is WAY too much voltage for a standard 5mm led, so it needs a resistor as thatdecade pointed out.

You will wire one resistor to each positive lead on each led.

If I may, you said you were going to the mall to get resistors and LEDs- I would suggest you don't buy them from Radio Shack unless you are only buying a coupe. They charge too much and their LED packs don't usually tell you the current it can handle or the viewing angle of the LED. So if you buy one LED from them for $1.50 and keep frying them it adds up fast.

I prefer to buy my bulk LEDs from SuperbrightLEDs.com. They have a good variety and selection for most colors etc. They have most resistors, but some they don't have. Check them out here http://www.superbrightleds.com/cat/component-leds/

I would also suggest that you look at thatdecades signature- he has a basic resistor tutorial that will help you.

 

[thatdecade]

Agreed, the radio shack at the mall is an ok place to buy electronic parts like LEDs, battery clips, and resisters. They are expensive if you are buying more than a few.

I buy my LEDs in bulk from ebay.

 

[Roku]

Thank you,both of you for your help.I'm very happy to report that the lights are working .

I'll keep that site in mind for the future. I got my LED's from the source and it is pricey. $5 for 2 LED's :/

Thanks again

 

[Revenant1988]

Thank you,both of you for your help.I'm very happy to report that the lights are working .

I'll keep that site in mind for the future. I got my LED's from the source and it is pricey. $5 for 2 LED's :/

Thanks again

No problem. I also recommend that when you are buying LEDs for a project like this that you buy a couple extra (resistors too), that way if you make a mistake you don't have to run out for such a small component. It's also nice to have a spare if one becomes damaged or breaks. For the violet LEDs in my suit I ended up frying a couple because of a cross in a wire with another wire.

Good luck!

 

[hobbitdude13]

What plastic is recommended for diffusing the LEDs? I'm doing some pre-build studies for War Machine, and have the perfect LEDs for the eyes but idk which plastic cover is best for diffusing the light.

 

[zombieprops]

What plastic is recommended for diffusing the LEDs? I'm doing some pre-build studies for War Machine, and have the perfect LEDs for the eyes but idk which plastic cover is best for diffusing the light.

It's really personal preference. Some people like using milk jug material, I like using clear plastic and sanding it with some fine grit sand paper. I've even seen people use foam to diffuse light. Just experiment with it a bit and see what you like the most.

 

[hobbitdude13]

It's really personal preference. Some people like using milk jug material, I like using clear plastic and sanding it with some fine grit sand paper. I've even seen people use foam to diffuse light. Just experiment with it a bit and see what you like the most.

Oh ok. I thought there'd be some fancy plastic or sth that people use. Thanks zg.

 

[Revenant1988]

Oh ok. I thought there'd be some fancy plastic or sth that people use. Thanks zg.

There is no fancy plastic or anything specific. Personally I found it a bit difficult to find opaque or "frosted" plastic that has a cloudy look to it yet still lets light through.

After awhile, the answer was right in front of me! I ended up using the plastic cap that came with my cans of Bondo. It was perfect!

Another tip, you can also diffuse leds by taking a small strip of sand paper and twisting it around the LED. I did this for the ones that were too bright in spots on my suit.

 

[zombieprops]

There is no fancy plastic or anything specific. Personally I found it a bit difficult to find opaque or "frosted" plastic that has a cloudy look to it yet still lets light through.

After awhile, the answer was right in front of me! I ended up using the plastic cap that came with my cans of Bondo. It was perfect!

Another tip, you can also diffuse leds by taking a small strip of sand paper and twisting it around the LED. I did this for the ones that were too bright in spots on my suit.

That's true, you can also cut or sand off the tip of the LED and it will help disperse the light even more because it's no longer a focused beam.

 

[DRG]

Okay, I'm confused by the specs on my LEDs.

Here's what it says:
10pcs 12 Vdc 5mm Blue wired LED's - 7 inch long red and black wires
Input voltage: 9~16 Vdc.
Viewing Angle: 20 degree
Low power consumption !!
Very bright !! Luminous Intensity 6000-8000mcd
New Ultra Bright LED with Built-In Current Limiting Resistors for 12 Volt Applications
http://www.amazon.com/Lights-wired-volt-leds-Blue/dp/B007O21Z5Q

Okay, so it says low power consumption but it also says 12 volts. Does this mean I need 8 AAs to power one LED? That sounds nuts based on everything I've read but the stats don't say anything about mA and I'm not sure what the difference between 'VDC' and battery voltage is, if any.

 

[Redshirt]

Okay, I'm confused by the specs on my LEDs.

Here's what it says:
10pcs 12 Vdc 5mm Blue wired LED's - 7 inch long red and black wires
Input voltage: 9~16 Vdc.
Viewing Angle: 20 degree
Low power consumption !!
Very bright !! Luminous Intensity 6000-8000mcd
New Ultra Bright LED with Built-In Current Limiting Resistors for 12 Volt Applications
http://www.amazon.com/Lights-wired-volt-leds-Blue/dp/B007O21Z5Q

Okay, so it says low power consumption but it also says 12 volts. Does this mean I need 8 AAs to power one LED? That sounds nuts based on everything I've read but the stats don't say anything about mA and I'm not sure what the difference between 'VDC' and battery voltage is, if any.

DRG,
What you are looking at are actually two components pre-wired together, an LED and a resistor. The resistor is the lump hidden under the black shrink wrap behind the LEDs in the picture. The LEDs only need/can handle a couple of volts. A very common voltage for DC power supplies is 12 volts--including automotive systems. All this vendor is doing is providing convenience for someone building a project to run on a 12v system. The correct resistor for these LEDs to run on a 12 volt system is already soldered in. If you used these, yes, you would need 8 AA batteries, but the bulk of your power would be wasted in the resistors. You most likely want loose LEDs or pre-wired without in-line resistors. Then, mindful of the power requirements/limitations of your specific LEDs and the voltage of the power supply you intend to use as well as how many of your LEDs will be wired in series, apply the formulas to calculate the size of resistor you need for each LED. Those formulas are here in this sticky and elsewhere on the internet. I have to also look them up every time I do LED projects, but it is not hard.

If you have already purchased these LEDs, you can either start over with new loose LEDs or cut off the resistor and replace it with the one correct for your power supply.

Battery voltage, volts, and VDC. Household current is alternating current (AC). It changes direction 50 or 60 times a second depending on where you live. LEDs can't function on AC. They need direct current (DC). Batteries are DC (have a positive and negative wire). Power supplies that plug into walls produce DC power by employing a rectifier that sorts the AC to run just one way (DC) and use a step-down transformer to reduce the voltage. So 'battery voltage' is expressed in 'VDC' as is the voltage from a power supply. Hope that helps.

Redshirt

 

[DRG]

Hmmm. It's strange... I hooked up one of the LEDs to a 4AA pack and it lit. Then I added 2 more in parallel and they all lit. So I'm even more confused now. It works, but it shouldn't from everything I've read (including Redshirt's post above). Unless maybe they're operating at less than full strength? Although the 1 LED setup and the 3 LED setup both looked equally bright to the naked eye. I'm curious how many more LEDs I can add to the chain without a visible drop in brightness, although I'm no electronics expert and I'm afraid this is a bad idea for some reason.

 

[Redshirt]

Hmmm. It's strange... I hooked up one of the LEDs to a 4AA pack and it lit. Then I added 2 more in parallel and they all lit. So I'm even more confused now. It works, but it shouldn't from everything I've read (including Redshirt's post above). Unless maybe they're operating at less than full strength? Although the 1 LED setup and the 3 LED setup both looked equally bright to the naked eye. I'm curious how many more LEDs I can add to the chain without a visible drop in brightness, although I'm no electronics expert and I'm afraid this is a bad idea for some reason.

Yes, you are not seeing them at full brightness, though they may not be much brighter correctly wired. Adding more LEDs in parallel won't show a drop in brightness until you exceed the battery's capacity to deliver current as each separate circuit is drawing on the battery independently. You could run this way with the excess resistors, but you will draw down your battery pack needlessly. You are looking at the difference between working and working well.

Redshirt

 

[thatdecade]

Good explanation Redshirt.

Agreed that the LEDs will be not as bright with your 4xAA running 6volt. I've taken apart 12 volt pre-wired LEDs from other sellers, found 500 ohm resistors in there. Running the 500 ohm resistor and LED with 6 volts, would be sending 12 mA to the LED. Plenty to light up. Is your decision if they are bright enough as-is.

Next time round, try ebay for more selection.
http://www.ebay.com/sch/i.html?_nkw=pre+wired+5V+LEDs

12v is better for automotive and computer projects. 5v is better for battery operated projects.

 

[Redshirt]

Good explanation Redshirt.

Thanks. That about used up what I know though. I did my one functioning electronics package for my Splaser by studying each component circuit on the internet until I amassed enough know-how to design it, then on to the next circuit requirement until I had a collection of subassemblies that would do the job. Some of it is laughably inelegant now, but it works. Good to see you back in here to bring the real knowledge.

Redshirt

 

[Karth15]

Hi, I'm putting together designs for a Halo: Reach armor set and I'm seriously considering putting in some sort of cooling system (I currently have an ACII cosplay, and even that gets hot). I've seen and looked into plenty of different ideas, I'm wondering if anybody here has an idea as to which one is best (an explanation as to why would be appreciated as well). Thanks guys and gals!

 

[Gokussj5okazu]

Hi, I'm putting together designs for a Halo: Reach armor set and I'm seriously considering putting in some sort of cooling system (I currently have an ACII cosplay, and even that gets hot). I've seen and looked into plenty of different ideas, I'm wondering if anybody here has an idea as to which one is best (an explanation as to why would be appreciated as well). Thanks guys and gals!

Well there's basic helmet cooling fans, to full body tube cooling. Lots of people have incorporated a camel pack into the rear part of their torso armor and that seems to help reduce temperatures while providing plenty of water. Obviously the fully body tubing would be the most effective, but quite complicated with some sort of pump and chiller.

 

[thatdecade]

Small fans are great for any enclosed piece that builds up with humidity, like the helmet.

A cos player I know recommended cooling towels. Are special towels you wet, then wring out. They feel dry, but stay cold.
http://www.walmart.com/ip/Perfect-Fitness-Perfect-Cooling-Towel/21666151