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Analog Tachometer for Fireblade Engine
Murdoc - 1/8/16 at 04:53 AM

Hi,

I have just purchased a locost powered by a 893cc fireblade engine. It's a bit of a project and I managed to do a bit of work in the two days of owning it before I went on holiday, which is where I write this post from.
Its got an Acewell dash but the tacho isn't working, the signal from the ICM is a bit of a mess, it switches from battery voltage to ~5V with a lot of other noise. I threw together a circuit with a Zener and low pass filter and while it seemed to work at high revs it was jumpy at low revs. I also tried a source follower circuit but calls to pack my bag meant I didn't get it to work in time. With enough poking I will get it to work, I know the Acewell is happy with a 50%d/c 5V square wave so I can replicate that with some filtering and a flip-flops then x2 on the dash but I have decided I prefer an analog tacho anyway, easier to see when pushing on. (I will get the Acewell going for the gear selector)

Is anyone using an aftermarket tacho on an 893 blade engine?

My explanation of things I have tried to clean the signal up with is if anyone has any ideas to try.

Cheers.

[Edited on 1/8/16 by Murdoc]


rgrs - 1/8/16 at 01:05 PM

I had the same issue, rapidly changing digital numbers didn't work very well so i used the one from the original clocks.

Removed it from the other gauge and installed into my dash.

das rev counter
das rev counter


There is currently one on ebay for sale.

My issue getting a clean signal was related to the ht leads, since changing them the signal is a lot cleaner.

Roger

[Edited on 1/8/2016 by rgrs]


Murdoc - 2/8/16 at 01:15 AM

Hi Roger, that looks good. Did you make the bezel and cover? The one on eBay is a bare dial which is why I started looking for an aftermarket one. Also, do you recall how it's wired up? I see two screw connections on the one on eBay but I would assume there should be 3, 12V, gnd and tach in.

I will order some HT leads. Thanks!


rgrs - 2/8/16 at 07:49 AM

There is a complete set of clocks HONDA CBR900 RR-R URBAN TIGER FIREBLADE CLOCKS/DASH/ODOMETER IN KM/H

Yes there are 3 wires, also using the full clocks also maintains the back lighting.

Roger


ReMan - 2/8/16 at 04:55 PM

FWIW I've never had any problem with my Vepor dash.
But FWIW I have the original clocks in place too and the signal I'm sure is piggy backed from the back of them


chrish - 22/8/16 at 04:29 AM

I've recently installed a Kubler tachometer and have been very happy with it. It's a digital though.

http://www.clrwtr.com/PDF/Kubler/Kubler-136-Frequency-Meters.pdf


Murdoc - 22/8/16 at 07:20 AM

I managed to get the Acewell very stable across the range. I used a high pass filter 1uF and 10k, with 160nF across the 10k to ground. In theory it's not a great filter design with the 160nF not doing a lot and just reducing the voltage slightly but it works well and now I have the gear indicator working too.

I ordered some fireblade dials from eBay but almost 2 weeks later they haven't arrived...