Electronics > Beginners
Sequential tail lights
Zero999:
--- Quote from: robjodicarter on September 24, 2018, 01:30:16 am ---So the 4017 only blinks once and does not continue to stay lit. And has a total of 10 spots for an led. What chip would let you keep them lit until they reset?
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Then what you need is to switch the LEDs with transistors, connected to diode OR gates.
See attached. O1 to O9 represent the outputs from the CD4017. O0 is not connected, because all the LEDs are off, when it's high. D1 to D16 are not critical: the 1N4148 will do. Q1 to Q9 can be any low power transistor, such as the BC548, BC338, 2N2222, etc.
Brumby:
--- Quote from: robjodicarter on September 24, 2018, 11:14:49 am ---Like this? Would that work?
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Yes, that would be able to get everything working - on the bench. You would still need some extra components in order to drive the bright LEDs you would need for a vehicle.
--- Quote from: drussell on September 24, 2018, 11:18:11 am ---Using arduinos for this is total overkill.
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If you are looking at cost or "overengineering" then maybe - but for someone just getting their feet wet, it's actually simpler to do and understand.
The LM3914 is the most direct single chip solution to drive the LEDs - but remember you still have to feed it a rising voltage.
drussell:
--- Quote from: Brumby on September 24, 2018, 11:26:38 am ---
--- Quote from: drussell on September 24, 2018, 11:18:11 am ---Using arduinos for this is total overkill.
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If you are looking at cost or "overengineering" then maybe - but for someone just getting their feet wet, it's actually simpler to do and understand.
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If he were coming from a computer background, I would agree.
Personally, I think it is much easier to just use the LM3914 with 10 transistors. No computer required, no programming, etc. I'm not saying that's not pretty simple stuff also, but implementing an LM3914 isn't exactly rocket science in the analog domain. :)
The OP can probably even splurge and buy both an arduino starter kit AND a few LM3914s and try both methods. Analog world and digital world. It is not expensive and neither are difficult. The unused parts can be used for other future projects. (This electronics thing is highly addictive, by the way, Rob... :) )
Will also need some LEDs (including some nice super-bright varieties for testing to see if they're what he wants for the finished units,) etc.
robjodicarter:
So I am looking for the cheapest smallest option that I myself can replicate. Looking to spend about 20-30 total on parts to build the module. I don't mind learning how to build it myself I just want to make sure that what I build won't die in 6 months. I just don't know how to go about it. So many ideas and you guys are the experts. I'm a mechanic by trade and can rebuild most any motor there is but that is completely different than electronics. That is why I have come to a forum that specializes in that aspect. Just want to build a sequential module the has 10 outputs for LED's or group of LED's that are bright enough for tail lights. They need to have 1 input that would allow them to all stay lit, then one input that tells them to run in sequence. The first one lights up, stays lit while the others follow until they are all lit. They all shut off and then start all over with the first one again. I can encase the module in a waterproof sealant after testing and completion. Then inside a box to ensure it won't be bumped around. If anyone can help me with the best way to do this that would be great. Thank you all for all of your input I have so many choices and don't know which way to go.
Rob
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Mr. Scram:
I guess you could use a shift register to create the "motion. You'd simply clock in lit LEDs and reset the register using the last pin to restart the motion. You could even have a few empty pins to build in a delay. To have enough pins for all the LEDs you desire, you can always link shift registers together create a longer shift register. Luckily that's easy to do. Of course you'd also need a clock circuit, which could maybe be a 555 timer circuit. That's a nice simple way of creating a more or less stable square wave to control the shift register with.
Maybe some transistors are needed to properly power your LEDs as a shift register can only drive so much current and you'd need some regulation to power your circuits with without blowing them up with a voltage that's too high. Most common integrated circuits work with 5V and more modern circuits can require 3,3V or even less. As someone has said some filtering may be needed to prevent the noisy environment from messing up your electronics, but getting the basic
Looking at it it seems you can connect a few popular and basic beginner circuits together to create what you want. It's actually a reasonably beginner friendly project!
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