Hi friends,
first of all, excuse-me for my Biiig delay in posting this message.
I was on vacation and far away from computers ! It was hot and sunny and very peacfull and there were girls and drink and all the other things.
Well, IÂ'm doing my speedometer using a processor.
The Timer 0 counts a 250 MS period and Timer 1 works as a pulse counter.
I know that my Opel Corsa has a Speed Sensor (VSS) which could be used to give me the right number of pulses for each carÂ's wheel revolutin (i guess it is 8 pulses / revolution in a 14 inch wheel)
IÂ'm trying to do a Schmitt Trigger with a Ne555 to capture de pulses from a sensor
The problem is that in this bad country no one wants to give the right information about the sensor. Everybody wants to sell the information in book for about US$ 80,00 ! ! ! ! ! !
have you ever did something with carÂ's Speed sensor ? Is the output of this kind of sensor in low voltage enough to work with the 555 ?
If you have any information about the speedometerÂ's implementation... Anything.... Iwould be happy !
thank you !
Sérgio
"that would be quite difficult to implement if, indeed, the "speedo needle" is a needle"
I agree it does sound a bit odd - but not entirely improbable...
It depends on what "speed" info the ECU actually needs - if it's just a crude stop/slow/fast, this might be fine... (remembering that a Corsa is a low-end car)
It might have a slotted opto thingy to detect the needle movement. If this is a fairly early car, before they went all digital, that would've been a cheaper development than a complete electronic speedo from scratch...
But the point is: the OP needs to know what it is before even thinking about what circuits may be "good" or "bad" for handling it!