Tacho how get it work?

[NiceMan]

http://www.finsquirt.net/forum/viewtopic.php?f=2&t=9154

Second post has diagram how get tacho work but i have problems at i not get..
If i get right information at relay need make noise when this works but my not work...
Relay not make any noise if pulse come from Mega or i connect 2n5551 center leg to ground whit 1k, 500ohm or 0ohm.
I have 5 that 2n5551 and i make 2 time connect allready and nothing change.
My original Tachometer get information from ignition coil.

Ford Taunus Coupe 2.0 ohc Turbo whit MegaSquirt 3.0 + ms3x
All another works but this i not get work.

Any orher way get it works?

[slow_hemi6]

Do you know the complete part number for the transistor?
2n5551 has a different pin out to 2n5551C. See note page 1 https://www.fairchildsemi.com/datasheet ... BT5551.pdf.
The relay should not be noisy unless you forget to remove the contact movement from the relay. The adapter only needs the coil.

[NiceMan]

ct2n5551ls read in parts.

I not forget remove contact, i have 2 relay, one i remove and one not. That where i not remove i use only test.
When its work i put that relays where i remove parts and use only coil.

Can use any output from MS3X to this without any component? Only put coil there?

[NiceMan]

Can use any output from MS3X to this without any component? Only put coil there?

This i need still answer...

[slow_hemi6]

I am fairly sure the only output that can be configured as tacho out is the specific tacho out, output pin. MS3x is shown in the manual as being able to drive the coil directly by tacho output pin.

[NiceMan]

As standard, the MS3X connector 'Tacho' output will provide a 0-12V signal that is suitable for most aftermarket
tachometers. (Ensure that JP3 is in place on the MS3X card and the S12C to JS9 jumper is connected on the
mainboard.

S12C to JS9 jumper i think at its missing... So need open ms3 and make it.

Edit:
There come +12 out from Tacho? Normal oldstyle Tacho connet to + or - in coil?

[slow_hemi6]

There will be 12v at the tacho output as the relay coil is acting like a pull up to 12V. This is correct opperation.
Oldstyle tacho connects to - terminal of coil. The negative terminal of a coil is not at ground/0v, it just connects to a switch in the form of points or a transistor driver. It only connects to ground when points are closed or transistor is switched on.
What triggers the oldstyle tacho is a flyback pulse the coil generates when the points open or transistor switches off. It is this effect the relay coil should simulate without having to use an ignition coil.

[Paul_VR6]

Depending on the tach it may care what kind of relay you use. On the vw's I normally work on a higher current (40a) relay is needed to generate a big enough pulse.

[NiceMan]

Depending on the tach it may care what kind of relay you use. On the vw's I normally work on a higher current (40a) relay is needed to generate a big enough pulse.

Thanks to know, if not get work i try bigger coil.

[ranster]

This is how i did it (last post):

http://www.msextra.com/forums/viewtopic ... 01&t=60561

[NiceMan]

This is how i did it (last post):

http://www.msextra.com/forums/viewtopic ... 01&t=60561

I try that but not make anything.. Realy not start "life".

One jumper missing and after test i tell what happened.

[ramz31]

A MSD 8920 tach adapter does the trick.

[NiceMan]

Let only peaple know at this star works =) Thanks to all.