Electronics Need help wiring something up? Thinking of adding an electrical component to your car? Need help troubleshooting that wiring glitch?

Homemade shift light

Old May 29, 2006 | 06:56 PM
  #1  
pizza_guy's Avatar
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From: Kansas, where the wind howls
Car: 84 Z28 H.O. w/Megasquirt II
Engine: semi-stock L69
Transmission: T-5 non W/C
Axle/Gears: 3.73 open
Homemade shift light

Has anyone the electronics knowledge to create a simple shift light from scratch with leds? Just the translation between the voltage of the tach wire and rpm would be a great place to start at. Any thoughts on how to make it adjustable would be great. I know somebody graduated college in this field.
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Old May 29, 2006 | 07:00 PM
  #2  
Apeiron's Avatar
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From: Mercedes Norte, Heredia, Costa Rica
Car: 1984 Z28 Hardtop
Engine: 383 Carb
Transmission: 4L60
Axle/Gears: 3.54 Dana 44
There is no translation of voltage to RPM on the tach wire. The tach signal is pulsed.
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Old May 30, 2006 | 07:52 AM
  #3  
NEEDAZ's Avatar
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From: Westminster, MD
Car: 89 IROC-Z
Engine: 355 TPI
Transmission: 700R4
Look around for 'frequency to voltage converters'. Go from there...
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Old May 31, 2006 | 12:56 PM
  #4  
pizza_guy's Avatar
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Joined: Mar 2004
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From: Kansas, where the wind howls
Car: 84 Z28 H.O. w/Megasquirt II
Engine: semi-stock L69
Transmission: T-5 non W/C
Axle/Gears: 3.73 open
thank you needaz
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Old May 31, 2006 | 01:01 PM
  #5  
Apeiron's Avatar
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From: Mercedes Norte, Heredia, Costa Rica
Car: 1984 Z28 Hardtop
Engine: 383 Carb
Transmission: 4L60
Axle/Gears: 3.54 Dana 44
Why use analog when it would be so much better to do the whole thing digitally?
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Old Sep 15, 2007 | 10:17 AM
  #6  
85_ZED28's Avatar
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From: St Catharines, ON
Car: '85 Z28
Engine: 350
Transmission: T5
Axle/Gears: 3.23
Re: Homemade shift light

Is the signal to the tach 1 pulse per engine revolution?
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Old Sep 15, 2007 | 04:10 PM
  #7  
Apeiron's Avatar
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From: Mercedes Norte, Heredia, Costa Rica
Car: 1984 Z28 Hardtop
Engine: 383 Carb
Transmission: 4L60
Axle/Gears: 3.54 Dana 44
Re: Homemade shift light

No, 1 per ignition firing. The tach lead is connected to the coil primary.
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Old Sep 15, 2007 | 04:35 PM
  #8  
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From: St Catharines, ON
Car: '85 Z28
Engine: 350
Transmission: T5
Axle/Gears: 3.23
Re: Homemade shift light

ok thanks, so that would be 4 pulses per rev, correct?
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Old Sep 15, 2007 | 04:37 PM
  #9  
Apeiron's Avatar
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From: Mercedes Norte, Heredia, Costa Rica
Car: 1984 Z28 Hardtop
Engine: 383 Carb
Transmission: 4L60
Axle/Gears: 3.54 Dana 44
Re: Homemade shift light

On a V8, yes.
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