led or shift lights to indicate speed.
Printed From: the12volt.com
Forum Name: Lights, Neon, LEDs, HIDs
Forum Discription: Under Car Lighting, Strobe Lights, Fog Lights, Headlights, HIDs, DRL, Tail Lights, Brake Lights, Dashboard Lights, WigWag, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=130796
Printed Date: July 07, 2025 at 2:34 AM
Topic: led or shift lights to indicate speed.
Posted By: kaoss
Subject: led or shift lights to indicate speed.
Date Posted: March 02, 2012 at 1:47 PM
The basic idea would be like a shift light, but instead of turning on at a certain engine RPM we want the lights to turn on at the vehicle's speed. The faster the truck goes. the more lights turn on. Currently the speedometer is mechanical, but can be converted to electronic. It's a 1993 nissan hardbody. What would we need to accomplish this?
Replies:
Posted By: oldspark
Date Posted: March 02, 2012 at 6:06 PM
If it's a pulse type speedo sender unit (as many Nissan cars have), then a Frequency to Voltage converter (LM2907) feeding a LED bargraph (or dot) driver (eg, one LM3914 per 10 LEDs), or maybe a range-converted LED tacho.
If its a mechanical speedo, then you need to add a pulse or voltage generator. I sensed the spinning magnet in my mechanical speedo, but you may be able to get a T-piece and add a Nissan pulse sender to the gearbox cable output.
If you have a voltage generator, then the pulse (frequency) to voltage converter can be omitted.
Mind you, these days people probably use PICs or Arduinos etc to convert and drive displays. Then it's easy to program flashing etc if a speed is exceeded, or light extra LEDs for warnings.
|