Best practices using 555/4017 & many LEDs

[NascentOxygen]

Just remind me what you have constructed. I think you have multiple boards each something along the lines of this subcircuit: https://www.physicsforums.com/attachment.php?attachmentid=49770&d=1344865437

How many LEDS and what resistor values are you using? They will be different for the blues (the arrangements for reds are identical with those for yellow).

 

[Freddythunder]

Hello again,

Here is a picture I put together with the values of the resistors and how I put the LEDs together. I'm not exactly sure where in the past four pages I got these diagrams, it's not exact to the post you posted. That was more for the transistor setup I believe.

http://www.themoviecraig.com/files/led-segments.png

After looking at the programming for the arduino and the lack of time I have on just this small piece of the larger project puzzle... I definitely want to change my mind and use the arduino as the processor. The outputs of the arduino are either high or low. So I can program it to toggle hi and low, then shut off for a while. Due to time restraints, I would love to have two of these outputs - connect one to all 40 reds, and the other to all 40 blues.

I figure I can use some solid state method using larger transistors, and tried to research but didn't find anything. I know there are relays, but am afraid they might not be fast enough - but desperate times...

thanks again for your help - I'm soooo close!

 

[Freddythunder]

Trying to use my brain and avoid further frustration, would this work?

If I used the LED calculator I found correctly:
All blue LEDs (at 120 mA Each array) would pull 480mA
All red LEDs (at 60mA each) would pull 240mA

According to this:
http://www.555-timer-circuits.com/increasing-output-current.html

Can I use 1 BC337 for each of the colors off of two of the circuits? One 556 switches a 337 for the blues and the other 556/337 for the reds?

 

[NascentOxygen]

Hello again,

Here is a picture I put together with the values of the resistors and how I put the LEDs together. I'm not exactly sure where in the past four pages I got these diagrams, it's not exact to the post you posted. That was more for the transistor setup I believe.

http://www.themoviecraig.com/files/led-segments.png

After looking at the programming for the arduino and the lack of time I have on just this small piece of the larger project puzzle... I definitely want to change my mind and use the arduino as the processor. The outputs of the arduino are either high or low. So I can program it to toggle hi and low, then shut off for a while. Due to time restraints, I would love to have two of these outputs - connect one to all 40 reds, and the other to all 40 blues.

I figure I can use some solid state method using larger transistors, and tried to research but didn't find anything. I know there are relays, but am afraid they might not be fast enough - but desperate times...

thanks again for your help - I'm soooo close!

Your image seems to show 7 red LEDS in a series string, to be powered by the vehicle battery, nominally 12 volts. Each red LED has approx 2.1v across it, according to your earlier measurements, making a total of 14.7v not including what is required across the current-limiting resistor. I can't see this working. I certainly would not have offered this as a viable arrangement. You can have no idea whether it will work, or what the current will be. Definitely inviting trouble in my opinion.

And it's similar bad news for the blue LEDS if you were to string 4 in series here.

 

[Freddythunder]

My apologies - the reds are 6 and 4 not 7 and 3... The way I built the thing, the resistor was going in the opposite direction of where I was counting. As for the LEDs, they do all work. I've had 6 of the 8 segments all bliking at once and all segments currently work. I also had a blue one flashing for a few hours; figured if it's going to burn out or blow up, I'd see something then.

 

[Freddythunder]

Project Finished!

Here we are again... One year and four months later.. Of course I think probably closer to a total of about 15 hours in that time span.. And it is finished.

I wound up putting together two 556 circuits and connecting the output to a TIP31 transistor for 4 segments of LEDs each. The circuits are currently in a breadboard, but for the time being, I think it will probably stay like that. I finished wiring up the lightbar and ran about 6 feet of wire off the end so that I can connect it to anything later if I change my mind, solder circuits together, get printed circuit boards, box up the breadboard, or any other option.

NacentOxygen, thank you for your help over the year!

I decided that with by budget constraints of not being able to spend anything else on this, I can take some strong magnets I have from projects past and be able to stick it to a metal car roof.

I also learned that driving around with those lights on my car WHEN THEY'RE OFF is illegal - so I'm glad I found that Arizona Revised Statute! (28-947) So when I do go and film, it will have to be on private property and I'll have to transport it in my trunk or something.



https://www.youtube.com/watch?v=VD2Qc26BAn4