Tacho options for a petrol dash?

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Cobra88
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Re: Tacho options for a petrol dash?

Post by Cobra88 »

any idea what tacho face number means ?
its slightly different to yours.

red and green areas slightly closer I think
Rick
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CJH
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Re: Tacho options for a petrol dash?

Post by CJH »

From the Brickwerks write-up the number seems to be something to do with the speed that the alternator turns at, which depends on the size of the pulley. At a guess, its the ratio of alternator rpm to crank rpm. Brickwerks' blurb suggests the trim pot on the PCB can be adjusted to suit different ratios. Not sure why the red and green areas would be different though - must be for different diesel engines.
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Cobra88
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Re: Tacho options for a petrol dash?

Post by Cobra88 »

maybe one Diesel & one Turbo Diesel I guess.

No white sticker on the back of my tacho and it has lower right corner mounting cracked looking from rear :oops:

Regards
Rick
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Ant-t
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Re: Tacho options for a petrol dash?

Post by Ant-t »

Looks great, well done :ok
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Re: Tacho options for a petrol dash?

Post by CJH »

I think I'm nearly ready to go with an order for a prototype PCB. I went for complete overkill with all the PCB traces - all 1mm - because I don't know enough to figure out how much current is flowing in each part of the circuit. I do know enough to know that 1mm is overkill though, because the resistors all look like 0.25W or 0.125W so the current must be quite small. But VW/VDO used 1mm traces on their board, so who am I to argue.

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I also don't know enough about the requirements of the capacitors, such as what type to use in this application, and there seems to be a huge difference in price between the different types. It may be that a different (cheaper) type might need a different footprint from what I've used for C1, C2 and C3. But this prototype should give me something to experiment with.
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Re: Tacho options for a petrol dash?

Post by Cobra88 »

Looks great Chris
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bigbadbob76
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Re: Tacho options for a petrol dash?

Post by bigbadbob76 »

CJH wrote:I looked at some contemporary VW tachos, and figured that some of them might be interchangeable, but I didn't find a unit that has the fuel and temperature gauges, and I need to retain those obviously. Are you suggesting that the basic tacho unit from a golf would install behind the faceplate of a T25 tacho/gauges combo?

Looks good. You've inspired me Chris. :D
I've just picked up this petrol golf one for £15 off ebay-

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The bits of PCB that are showing look like your early petrol one.
I also got the fuel gauge to suit but will have to source a temp gauge.
It'll all take a bit of fabrication of backing plate etc but it's not beyond me.
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CJH
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Re: Tacho options for a petrol dash?

Post by CJH »

That looks like a good buy. Is the faceplate diameter the same as for a T25?
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Re: Tacho options for a petrol dash?

Post by bigbadbob76 »

I'm hoping so. :lol:
Based on "the samba" posts it fits, just the flat bottom edge which leaves a slight but not noticeable gap.
I got both gauges for £10 each, just missing the backplate for some reason, I'll message the seller and see if he's got it, but I think I'll need to make my own backplate anyway as you did.
If you're ok with it I'll post my findings here, or start another thread if you prefer. :ok
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Re: Tacho options for a petrol dash?

Post by CJH »

bigbadbob76 wrote: If you're ok with it I'll post my findings here, or start another thread if you prefer. :ok

In this thread is fine by me - makes sense to keep the discussion all in one place. It'll be interesting to see what needs to be done to fit the golf gauges.
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Re: Tacho options for a petrol dash?

Post by bigbadbob76 »

Me too, at that price it was worth experimenting.
Did you get PCB's made to replace the blue flexi film? or do you just use veroboard?
I'd be interested in a pcb if you did. they look very professional. :ok
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Re: Tacho options for a petrol dash?

Post by CJH »

bigbadbob76 wrote: Did you get PCB's made to replace the blue flexi film?

I did.

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£30 including first class postage, plus £12.50 if you want a pair of 3D-printed bulb holders (the kit includes 3D-printed bulb adapters so you can use 5mm LEDs in your existing bulb holders if they're still OK). Almost complete instructions here, if you want to see what's involved before committing.
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Re: Tacho options for a petrol dash?

Post by CJH »

CJH wrote:I think I'm nearly ready to go with an order for a prototype PCB.

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I placed an order for 10 of these last night. They're already 77% complete - just waiting to be cut to shape, inspected and then shipped. Back in the day it used to take Boots longer to make 24 prints from a roll of film.
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Re: Tacho options for a petrol dash?

Post by bigbadbob76 »

CJH wrote:
bigbadbob76 wrote:£30 including first class postage.

That seems very reasonable considering all the design work you've put in. :ok
I couldn't make one for that. (well I could with veroboard but yours look so much better).
I'll PM you.

I think I might be able to fit my tacho mechanism into the clock housing, that way I keep the back plate from the clock.
We'll see when it arrives.

P.S.- I found this so thought I'd post it here in case someone can use it. :wink:
Dunno how you'd print it but I'm sure someone can.

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CJH
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Re: Tacho options for a petrol dash?

Post by CJH »

Look what the DHL man brought today.

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So far so good - fits perfectly. I can't fully populate it yet as the ICs haven't arrived yet.
"I'm a man of means, by no means....King of the Road!"

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