Hey electronic guru's!
Would it be possible to built an F1 style rev-limit LED bar for a motorbike (or car)?
Do you know how RPM's are signaled up to the tacho from the gear box? Is it pulse-width-modulated?
Here's what I would like to do:
A LED bar with 5 (red) LEDs.
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| O O O O O |
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The LED's turn on quickly as the red-line is approached. On my bike the redline is 10k so the lights could turn on (left to right) at 8k, 9k, 9500, 9800 and 10k for example.
What would you need to do that?
Could a PIC processor decode the signal from the gear box and control the LED's?
How do you lower the battery voltage from 12 to 3V to run the pic and drive the LEDs?
Is there an easier choice than the PIC (can it be done with Radio Shack parts?)?
I'm pretty excited about this - please help me out!
Oh, as always - the cheaper the better... And for a bike, it needs to be small.
Cheers,
Andre
Rev limit LED indicator - DIY???
Started by
int2str
, Jan 15 2002 08:22
3 replies to this topic
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#2
Croaky
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- 193 posts
- Joined: May 01
Member
Posted 15 January 2002 - 10:11
Well, I'm certainly no expert 
but I know that there's actually a fairly common chip which takes a voltage as input and drives LEDs in a bar graph. It's called an LM3914. Here's a web page with its data http://www.national..../LM/LM3914.html. It'll run off a 12V supply no problem. If you can get your tacho level as a voltage, you could make a circuit like you're talking about that would fit in a matchbox, and no PIC programming.
but I know that there's actually a fairly common chip which takes a voltage as input and drives LEDs in a bar graph. It's called an LM3914. Here's a web page with its data http://www.national..../LM/LM3914.html. It'll run off a 12V supply no problem. If you can get your tacho level as a voltage, you could make a circuit like you're talking about that would fit in a matchbox, and no PIC programming.
#3
david_martin
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- 1,989 posts
- Joined: October 00
Member
Posted 15 January 2002 - 10:33
There was a project in the Australian electronic hobbyists magazine "Silicon Chip" (September 1998 IIRC) that does exactly what you describe. I think they may have the PCB and necessary components available as a self assembly kit, although I am a long way from Australia atm and cannot easily check. A start for you, though
#4
AdamLarnachJr
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- 525 posts
- Joined: June 01
Member
Posted 16 January 2002 - 02:39
That is fairly easy. I was considering doing it on my project car. All I needed to do was to buy the led's from Auto Meter, and the tachometer sender unit, hook it up to a distributor and ground, and there ya go!
I just set each light to go off at different RPM's, like a rev limiter or warning light.
Green = 5000rpm
Green = 5400rpm
Green = 5800rpm
Yellow = 6000rpm
Yellow = 6100rpm
Red = 6200rpm
I just set each light to go off at different RPM's, like a rev limiter or warning light.
Green = 5000rpm
Green = 5400rpm
Green = 5800rpm
Yellow = 6000rpm
Yellow = 6100rpm
Red = 6200rpm
