This will take you to the main site where there is history, technical information and other information on these cars.
This takes you back to the main page of the forums.
This is the control panel to change your password, information and preferences on this message board.
Click here if your lost your password or need to register on this message board. You must be a registered user to post. Registration is free.
Search this board for information you need.
Click here to buy cool Squarebirds mechandise.
Click here to support Squarebirds.org. For $20 annually receive 20mBytes webspace, a Squarebirds e-mail address and member's icon on the message board.
  #41  
Old 01-20-2013, 08:06 AM
Yadkin Yadkin is offline
Banned
 
Join Date: Aug 11 2012
Posts: 1,910
Yadkin is on a distinguished road
Default

Yes I'm using the diode. I'd like the bulbs a bit brighter as they are running at 62% of their rated amperage. But with this set up I can skip the potentiometer and not worry about burn out.

Or I can rewire to 7 sets of 4 with the potentiometer and dial it in to closer to the rated maximum.

Just approximating, but that should get me 62% x 7 4 = 109% without the potentiometer.
Reply With Quote
  #42  
Old 01-22-2013, 02:32 PM
simplyconnected's Avatar
simplyconnected simplyconnected is offline
Slow Typist
 
Join Date: May 26 2009
Posts: 7,121
simplyconnected is on a distinguished road
Default

Man, if it's not one thing it's another. My order finally came in. I connected a car battery (with a charger to bring it up to 14-V) with seven LEDs and two VOMs, one for voltage (on the left) and the other for current (on the right).

Using the least components, we have four branches of SIX LEDs and one with FOUR, giving us 28 LEDs. Here's the circuit:

As you can see, I took one LED out and added a resistor in each branch to get less than 20mA. Here's the branch for SIX LEDs:

...and FOUR LEDs:

These LEDs are so bright, my camera couldn't get much detail. The brightness washed the picture out but you can see what's going on.

After grabbing all these great pictures, I tried posting. Oh, no... the server was full, and wouldn't let me post. I thought the worst because our server lives about ten miles from me and it's been cold (ten degrees F), windy, and many houses are without power.

It looks like we're up again. Cross your fingers.

Got questions or concerns? Shoot them by me. - Dave
__________________
My latest project:
CLICK HERE to see my custom hydraulic roller 390 FE build.

"We've got to pause and ask ourselves: How much clean air do we need?"
--Lee Iacocca
Reply With Quote
  #43  
Old 01-22-2013, 06:25 PM
Yadkin Yadkin is offline
Banned
 
Join Date: Aug 11 2012
Posts: 1,910
Yadkin is on a distinguished road
Default

Wouldn't it be easier to set it up with 7 sets of 4 and a single resistor after the diode?
Reply With Quote
  #44  
Old 05-07-2013, 06:31 PM
Yadkin Yadkin is offline
Banned
 
Join Date: Aug 11 2012
Posts: 1,910
Yadkin is on a distinguished road
Default

My dad is here for a few days, he's a retired electrical engineer and looked this over.

The LEDs are rated at 5v maximum reverse polarity. Since they are wired in series of 7 that's 35v. Even wired wrong, the 12v battery won't fry them. He suggested I nix the diode.

When I take the diode out the circuits brighten up per the original plan. No resistors or other junk needed.

DONE!
Reply With Quote
  #45  
Old 05-07-2013, 08:05 PM
simplyconnected's Avatar
simplyconnected simplyconnected is offline
Slow Typist
 
Join Date: May 26 2009
Posts: 7,121
simplyconnected is on a distinguished road
Default

...just a word of caution: LED's are current devices. That means OHM's law doesn't quite work with LEDs. Use THIS CALCULATOR for your circuit. If they have a 20ma rating (0.02a) I would run them at fifteen milliamps. They will last MUCH longer that way.

I realize that you are using them for simple brake lights that don't come on or stay on for very long. But LED's can fade quickly if driven hard (using threshold current) and they aren't very forgiving if someone reverses your battery leads, even momentarily. How likely will this happen? Probably not very likely but if it ever does you're really going to be mad. That's the reason for the diode. Another 'trick' I do is, make a simple bridge from four 1N4004 diodes. That way you cannot get the polarity wrong and it safeguards your LEDs.

Resistors and diodes are cheap. If you need any I will send them to you. - Dave
__________________
My latest project:
CLICK HERE to see my custom hydraulic roller 390 FE build.

"We've got to pause and ask ourselves: How much clean air do we need?"
--Lee Iacocca
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -4. The time now is 10:36 PM.

Driving, racing or working on cars can be hazardous. The procedures and advice on this website including the message board are opinion only. Squarebirds.org and its webmasters and contributors do not guarantee the correctness of the advice and procedures. The Squarebirds.org and its webmasters assume no liability for any damage, fines, punishment, injury or death resulting from following these procedures or advice. If you do not have the skills or tools to repair your car, please consult a professional. By using this site you agree to hold harmless the Squarebirds.org, its authors and its webmasters from any resulting claim and costs that may occur from using the information found on this site.

Powered by vBulletin® Version 3.6.8
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Any submissions to this site and any post on this site becomes property of Squarebirds.org . The webmasters reserve the right to edit and modify any submissions to this site. All material on this is site is copyrighted by the Squarebirds.org. Reproduction by any means other than for personal use is strictly prohibited. Permission to use material on this site can be obtained by contacting the webmasters. Copyright 2002-2016 by Squarebirds.org.