Tacho 'un'booster

[CrUZida]

Has anyone successfully got a new tacho working with an 'older style' ignition system?

While it works fine at idle and below 2000rpm, in the middle to upper end it jumps all over the shop (MA70 digital tacho).

Do I just need to install something to 'clip' the voltage to 5V ?

[hemi twofifteen turbo]

By older are you referring to a points system? maybe use a cap to filter out high freq's from the contacts or add another condenser? I don't think >5v would matter and if anything with revs u get less signal, but I would assume it's interference??

[wilbo666]

I'm pretty sure 1JZGTE at least outputs 12V, not 5V as the tacho output...

You could always try using a zener diode to cap the voltage to ~12V

What are you using to convert 4/8 pulses to 6 out of interest?

Cheers
Wilbo

[CrUZida]

By older I mean a signal similar to the one that a coil produces, not one that is generated by an ignitor.

Nothing yet to convert the signal, not particularly phased yet.
If I can't find something off the shelf for <$50 I'll probably use a Jaycar speedo corrector.

Zener diode had come to mind, but its been ages since I looked that then I wasn't sure what voltages they came in.

[Disturbed1]

pull down resistor??

[wilbo666]

Yeah you could always setup a pull up resistor and diode...

                                      +12V
                                          |
                                          \
                                          / (Pull up resistor)
                                          \
                                          |
                                          |
Older tacho output ----<|------------ Newer tacho

Cheers
Wilbo

[ViPeR_NiPPleX]

could try an optoisolator, I suspect the irratic rpm at higher revs could be the duration the signal has gone high isn't sufficient to trigger the tach.

[Mos]

The earlier tachos had either a 15k resistor or a 30k series resistor depending on which output they were hooked up to. You could just try to add one...

[ddeane]

Have a look at this link - it should solve your problem.

Cheers Craig

http://www.toymods.net/forums/showth...highlight=taco

[CrUZida]

I need an answer to this.
http://www.toymods.net/forums/showpo...6&postcount=33
Unfortunately that thread did not provide

Will try Mos' suggestion first, then the zener diode.

[big_zop]

So did you have any success sorting this out?

[CrUZida]

Unfortunately not. I've been lazy, and am just putting up with a wack tach for the moment.

[andyroo]

Ask Hydra, he and myself had the same problem with tacho once 1GGTE was in, he managed to fix it, but I myself am very lazy, he even sent a wiring diagram, but Ive no idea where it is.. Good luck.

[CrUZida]

Thats a tacho booster, I need the opposite.

[CrUZida]

The earlier tachos had either a 15k resistor or a 30k series resistor depending on which output they were hooked up to. You could just try to add one...

http://www.toymods.net//forums/showp...35&postcount=5

33k according to that.

Sounds like the best option so far.