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05-27-2009, 07:41 AM | #1 |
Hack.... What hack ??
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Basic Electronics Help Needed !!
Hi Guys. Hoping someone here with some basic electronics knowledge can
help me out. My nephew is doing a class project and wants to make a simple working traffic light. Because I have a very limited understanding of electronics <cough> none <cough> I'm hoping someone can show me the wiring diagram that I'd need to put together. Basic plan is to use 3 flash light bulbs and hook them up to a simple 3 way slide switch and battery pack (2 AA batteries or 9 volt ?),so the left position illuminates the red light, the middle illuminates yellow, and the right position illuminates the green. A further on/off switch will also be included for the power. Anybody feeling generous that can help me out with the wiring ? Nothing fancy, just something simple enough for him to explain how it works, and how it was wired. |
05-27-2009, 08:59 AM | #2 | |
Start another Oil Thread!
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here's a ladder logic wiring diagram
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05-27-2009, 09:03 AM | #3 |
Captain Slow
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i forgot how to do it,but once i made it on my junior high school project.
Why don't your nephew just buy the knock down one? |
05-27-2009, 09:15 AM | #4 |
Captain Slow
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05-29-2009, 11:09 PM | #5 |
Hack.... What hack ??
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Sorry Tamago, I can't really translate the ladder logic diagram.
Any chance you could simplify it on the diagram I posted ? And unfortunately, the 2nd on/off switch is a necessary evil I'm afraid. |
05-30-2009, 12:15 AM | #6 |
ULTIMATE
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05-30-2009, 06:29 AM | #7 |
Hack.... What hack ??
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05-30-2009, 10:51 AM | #8 |
Drives: yaris 08 sedan Join Date: Oct 2008
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Get your nephew some extra brownie points for creativity and run it off solar power.
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05-30-2009, 10:53 AM | #9 |
School'er of hard knocks
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FYI, you're going to need a resistor with those LEDs.
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05-30-2009, 11:28 AM | #10 | |
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Quote:
Keeping that current around ten mA would run the LEDs cooler... I'd recommend a 560ohm resistor, which would give you a more gentle 11mA to 12.5mA range, assuming a 3 to 2 volt drop across the LED. I used to use 470ohm resistors with 5 volt sources and LEDs... I like to keep things on the low to middlin end to preserve function and reduce heat on working parts. Gene PS If someone can scan in the LED's spec sheet we can do a better job of calculating a good current limiting resistor for this project. |
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05-30-2009, 08:56 PM | #11 |
ULTIMATE
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5mm axial lead LEDs are rated for 20mA or greater.
Red: forward voltage = 2.2V, forward current = 30mA Green: forward voltage = 3.5V, forward current = 25mA Yellow: forward voltage = 2.0V, forward current = 30mA The 390 ohm resistors are fine for all three LEDs. |
05-30-2009, 09:14 PM | #12 | |
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Quote:
Gene |
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05-30-2009, 09:17 PM | #13 |
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05-30-2009, 09:35 PM | #14 |
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Don't buy it. I've seen Max If as low as 50mA and even 30mA for some LEDs. Depends upon the manufacturer, lead heat conductivity and other factors.
I think we could both agree that whoever is building this thing better take a moment to read the If figures on the cut sheet. If not they could experience untoward failures. Been there, done that.... Gene |
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