Upgrading the tachometer, to remove that bounce |
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Upgrading the tachometer, to remove that bounce |
timothy_nd28 |
Aug 11 2013, 05:42 PM
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#1
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Advanced Member Group: Members Posts: 2,299 Joined: 25-September 07 From: IN Member No.: 8,154 Region Association: Upper MidWest |
First I would like to give thanks to Terry, my uncle, for his time on this and my other RGB backlighting project. He has spent more time working on this than he cares to admit. He's more of a Corvette guy, but his vast knowledge and willingness to help, transcends which benefits our community.
Okay, so I have been told that our tachometer has a problem with bouncing. I personally have never seen this problem and I have to admit that I've never really paid much attention to the tach while driving, so I decided to put the signal generator on the tach and see how it performs. This signal generator bypasses the ignition system and provides a clean signal. This also serves as a control because a bad condenser on the dizzy can cause problems as well. This video shows the untouched tach in its original state running on a function generator. As you will see, it does bounce and over shoot during the sweeps. https://www.youtube.com/watch?v=rbC37l1z_oA This next video shows our tach but with a cheap modern 30 dollar tach stuffed inside. The bounce seems to have disappeared, and there is no more overshoot during the sweeps. https://www.youtube.com/watch?v=cmk1lSop_iE The VDO tach was designed for mass production and had a very simple but effective design. This modern tach uses an air core massless motor which is controlled by sine/cosine inputs which tends to be a bit more responsive and accurate. The original vdo design is a motor/spring contraption which will always have some bounce. Over time, capacitors and dampening fluid may leak or fatigue which will aggravate the problem. In this write up, I will show how to incorporate a off the shelf 30 dollar tachometer commonly found at the auto parts store, and make it work with our VDO gauge can. |
timothy_nd28 |
Jan 23 2016, 11:29 AM
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#2
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Advanced Member Group: Members Posts: 2,299 Joined: 25-September 07 From: IN Member No.: 8,154 Region Association: Upper MidWest |
As a HVAC tech, I've been busy with this recent snap of cold weather. Sorry for not replying to your PM. Tom, you mentioned that you are installing a Honda V6 which I'm not familiar with the ECU's tach signal, it may be canbus. It could work but I can't tell you that it will with 100% certainty. You can do a quick test by purchasing the tachometer from AutoZone and temporarily wiring it. Set the slider switch to 6cylinder and try it. If it works, box up your 914 tach along with the Autozone 30 dollar tachometer, and I would be happy to put it together for you. If it doesn't work, simply return the tachometer to the part store (IMG:style_emoticons/default/biggrin.gif)
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