Author Topic: Series one revcounter/tacho converted to diesel  (Read 2612 times)

July 09, 2012, 08:34:49 am

regcheeseman

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Series one revcounter/tacho converted to diesel
« on: July 09, 2012, 08:34:49 am »
Always up for a challenge, a mate sent me his series 1 revcounter to convert to run on the W terminal on a diesel engine.


I've got it callibrated pretty close, it reads a little low below 1K but then is good round to 7000.
The position it is sat on at the start and end of the video is 900 rpm - which is 214Hz



Reply #1July 11, 2012, 03:20:13 pm

Syncroincity

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Re: Series one revcounter/tacho converted to diesel
« Reply #1 on: July 11, 2012, 03:20:13 pm »
Need more details on the conversion!

...also, make sure you have a video camera running when you take it to 7K.  ;D
JC McCavitt
'86 Syncro GL Camper AAZ
'98 Jetta Wolfie
'04 Passat Variant GLS 4Mo 5MT

Reply #2August 13, 2012, 11:02:25 am

tranny

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Re: Series one revcounter/tacho converted to diesel
« Reply #2 on: August 13, 2012, 11:02:25 am »
Did you use a frequency divider ?

Reply #3September 01, 2012, 04:10:02 pm

BLZEEDUB

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Re: Series one revcounter/tacho converted to diesel
« Reply #3 on: September 01, 2012, 04:10:02 pm »
Ive the same revcounter/tacho that ive recalibrated to diesel function (by myself) as per regcheesman's thread on here; page one.

I hooked up + and -, and the signal to the W terminal; the recvounter will 'idle' for a spell at 1000rpm, but the revcounter/tacho completely dies when I rev the engine; allow the engine to return to idle and it will read 1000rpm again for wahile tho it fails to even register that after 3 or 4 minutes.

Im not that up on electronics; I just followed the thread for 'westmorland clocks' (looked the same as the S1 Golf VDO board) - the only 'resistor I didnt have was a 72ohm for R2; I used a 68ohm resistor...

Anyone any ideas what component/components could be causing this??

Thanks in advance....
AAZ'd MK1 caddy (WIP)... and B2 Passat 1.6d 2 1.6GTD

Reply #4September 13, 2012, 05:03:55 pm

tranny

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Re: Series one revcounter/tacho converted to diesel
« Reply #4 on: September 13, 2012, 05:03:55 pm »
Not done this with a vw but done several for land rover diesels with petrol engine revcounters, usually either a divide by 4 or divide by 6 function is required, a resistor won’t do much apart from reducing the voltage, what you need to do is reduce the number of pulses per revolution that the revcounter is "seeing".
If you start by connecting your revcounter to the w terminal, use a quality strobe (needs a rpm readout if the petrol engined vehicle doesn’t have one) connected to a petrol engine.
 Put a white mark on the vw crank pulley start the vw and petrol engines point the strobe at the vw pulley, bring up the revs on the vw until the white mark is stationary, read off the rpm on the strobe (or petrol tacho) and you have your engine speed, compare this to the tacho connected to the w terminal and you have you divide by factor