Tach conversion??

[nomad]

Has anyone used the Spiyda tach modification on the early tachometers? If so have you used it with a electronic conversion and which one?

Kurt
26/3754

[nomad]

Make that a electronic ignition conversion from points....

Kurt

[pptom]

I have in my +2 and midget running a modern Suzuki engine.
The +2 first ran on standard dizzy then an ECU when I went injection, no problems with it at all. The Suzuki / midget runs and old style ECU with an electronic dizzy and it runs fine with that too.
Has 4 possible inputs for different sources. Spidya are very, very helpful too.

[checkrail]

I'm running an Accuspark electronic distributor on my +2 with a standard RVI tacho. When I turn the ignition on the needle flicks over to max and then returns.
The car still runs as it should with no other electrical problems. I contacted Accuspark {by e-mail as they won't discuss technical problems on the phone} eventually they recommended Spiyda.
Looking on their website the 'RVI Buffer' would seem to be the answer to my problem.
I will give them a call, but surprised that Accuspark couldn't offer any explanation themselves.

John

[nomad]

Thanks folks. Seems to be good recommendation.

Kurt

[jk952]

Hi Kurt,
On my previous S2 I put a Spiyda kit in the orig. tach. fit fine and worked great with both the std. dist. and a Petronics unit. (changed car to neg. ground)
The original circuit board is now on display on my bookshelf…not up to date enough on electronics to know exactly what was wrong with the orig., but didn’t care as the other was such an easy solution…. lol…
Jack

[nmauduit]

I'm running an Accuspark electronic distributor on my +2 with a standard RVI tacho. When I turn the ignition on the needle flicks over to max and then returns.

Same with me with a 123.nl and Bosch red coil (1.8 Ohm) , the needle flicks up upon contact and starting sequence, or during any instability of the power supply at the dash (e.g. when I use the windshield fan which draws a lot of current upon starting) : I've planned to put a 10V regulator before it in hope it would stabilize it, as sometimes it gets stuck at the max and only comes back after turning off the contact. I suppose the electronics is sensitive to power supply stability (I may even need to add a local capacitor to help smooth out the input voltage of the tacho module).

Besides that, the ability to tune it precisely was quite convenient iirc (I did the conversion several years ago).

[billwill]

If you put one of those switching 10v regulators in the power feed to the Tacho, it will probably go really crazy as those kind of regulators output a 'square' (12v->0v) waveform with an AVERAGE of 10 volts.

The most common tachos have a zener diode inside and do not need any further regulation of the power supply.


Two transistor version of RVI tacho. https://mgaguru.com/mgtech/electric/et202d.htm



One transistor version of RVI tacho. http://www.mgb-stuff.org.uk/harvit.htm



Conversion to RVC type tacho.
https://spiyda.com/tachometer-electronics.html

[nmauduit]

If you put one of those switching 10v regulators in the power feed to the Tacho, it will probably go really crazy as those kind of regulators output a 'square' (12v->0v) waveform with an AVERAGE of 10 volts.

no, I'll try some solid state regulators, one for the tacho (with the capacitor) and one for the fuel gauge which I've found vibrating around 1/4 level in some circumstances, possibly precisely because of the nature of the stock vibrating regulator (could be a mechanical issue, so I'll see). Now I still need to get the dashboard loose, which is a dreaded moment that I've managed to postpone for quite a while...

solid state 10V dash instrument regulators

[checkrail]

I had a word with Chris about using a RVI Buffer, but he suggested leave well alone mainly due to the age of the Tacho.
The flicking over to max when turning on is usually caused by the starter motor.

What an honest chap! John

[nmauduit]

If you put one of those switching 10v regulators in the power feed to the Tacho, it will probably go really crazy as those kind of regulators output a 'square' (12v->0v) waveform with an AVERAGE of 10 volts.

no, I'll try some solid state regulators, one for the tacho (with the capacitor) and one for the fuel gauge which I've found vibrating around 1/4 level in some circumstances, possibly precisely because of the nature of the stock vibrating regulator (could be a mechanical issue, so I'll see).

well, to conclude (at least for now) on this solid state regulators attempt : no joy ...

I have not done a full characterization of this mod, just tried to swap the Lucas vibrator regulator output by the 7810 modules mentioned above, and
- the readout on the Spydia tacho was very low, at least half the actual readout and possibly event a third or a quarter : I suspect the way I originally setup the Spydia module may have caused it to lock on variations of the power supply (it may very well be possible to get it to operate on the solid state regulated supply, but that would have required a recalibration, which I was not equipped to perform then)
- the readout on the fuel gaude was low as well (possibly due to a lack of current ? though I was not expecting the fuel gauge system requiring more than 1A - then not enough voltage? ) , plus the annoying vibration was still there, so it is definitely a mechanically induced vibration (a resonance linked to some engine rev), the gauge would need some overhaul I suspect...

In any case, I reverted both gauges to the original Lucas vibrating regulator outputs for now, awaiting a long delayed dashboard change or reveneer occasion to look into these electrical gremlins again...