Member Since: 06 Nov 2004
Location: Hook Norton
Posts: 18444
What do you want the signal for? Why are you trying to feed it into a relay?06 D3 SE / 15 LR D90 XS SW / 88 LR 90 Td5 / 68 BMW 2000 ti
Any issues with the site let me know!
31st Mar 2020 12:01 pm
LR3norway
Member Since: 25 Dec 2016
Location: NORWAY
Posts: 193
I'm making a system on the car. But I need to cut the power feed when the car is moving.
31st Mar 2020 12:31 pm
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10359
doubt that relay will work with pulses
31st Mar 2020 1:09 pm
Martin Site Admin and Owner
Member Since: 06 Nov 2004
Location: Hook Norton
Posts: 18444
Ok well it's unlikely that this signal is at 12V when the vehicle moves and 0V when it's stopped (or vice versa) which is what you want.
It's probably a square wave pulse, and it will output a certain number of pulses per mile.
Even if it is 0V when stopped, you couldn't just trigger the relay from this kind of signal as the relay would "chatter" due to the rapid changing of the signal from 0V to 12V and back again.
Ideally you would need a microcontroller of some kind, with a buffer circuit, to detect the pulses and turn the relay off when the pulses start.
Depending on what the signal does, you might be able to buffer it and then use that to charge a capacitor to hold the relay coil active when moving.
But you really need an oscilloscope and the ability to have a play with some components to do this.06 D3 SE / 15 LR D90 XS SW / 88 LR 90 Td5 / 68 BMW 2000 ti
Any issues with the site let me know!
Have you an altox fitted? Might have a suitable output..
Dean
====================================
2011 D4 XS - OBD port protection, RLD spare wheel protector, All LED interiors lights, Timed Climate enabled, iiD tool paired.
2011 D4 Landmark - Stolen from same dealer before I paid for it
2011 D4 GS - Stolen whilst at dealer ... All LED interiors lights, DRLs, Spare Wheel protector.
1996 300Tdi - Eaten by tin worms
31st Mar 2020 1:29 pm
LR3norway
Member Since: 25 Dec 2016
Location: NORWAY
Posts: 193
Would think the can is flat when the car is stationary?
Thinking these relays don't use more than 5mA for the trigger wire, it should not disturb the canbus. Canbus is 2,5-5V ? A diode to protect the abs module, and a 5V capacitor after?
I have no idea, but worth a try?
Don't have altox.
31st Mar 2020 2:06 pm
vjuntura
Member Since: 28 Mar 2019
Location: Oulu
Posts: 20
Reading your posts, no offense, but with that kind of knowledge of electronics, I would NOT try anything.
Can bus is not flat when vehicle stationary, can goes sleep only when the vehicle goes to sleep. And no, I would never control a relay using canbus wires.
Try to read background about PWM first. If there really is a PWM signal in that green wire, it should be quite easily readable (and reverse engineerable) for example with Arduino. Then you could control your relay according to the PWM signal using that same Arduino.
2011 D4 XS - OBD port protection, RLD spare wheel protector, All LED interiors lights, Timed Climate enabled, iiD tool paired.
2011 D4 Landmark - Stolen from same dealer before I paid for it
2011 D4 GS - Stolen whilst at dealer ... All LED interiors lights, DRLs, Spare Wheel protector.
1996 300Tdi - Eaten by tin worms
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum
... All LED interiors lights, DRLs, Spare Wheel protector.
