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Sun Feb 21, 2010 8:21 pm

Can someone tell me what is the purpose of the vibrator that is attached to the back of the fuel guage?
The reason I am asking is because I am planning to install Porsche 914 gauges in my '69 beetle. I have tested the 914 fuel gauge and it seems to work without the VW vibrator but I don't want to damage something by leaving it out if I need it. Thanks.

Sun Feb 21, 2010 8:23 pm

It evens out the voltage so the gauge doesn't swing side to side when you make turns.

Sun Feb 21, 2010 8:29 pm

Glen, does that mean that I should figure out a way to wire the vibrator to the porsche fuel gauge? The porsche fuel gauge doesn't seem to have one unless it's internal.

Sun Feb 21, 2010 8:30 pm

I don't know.

I also don't know if the stock VW sender will give accurate reading for the 914 gauge.

Mon Feb 22, 2010 12:19 am

I thought the purpose of the vibrator was to provide always the same voltage to the fuel gauge, so it reads the same when, for example, you turn the lights on. I really don't think it has nothing to do with the needle moving on corners. It is only my opion, and I am not an expert.

I am using 914 gauges without vibrator. The fuel gauge is not very accurate, it reads 3/4 when full. It takes 300km to reach the 1/2 mark and only 100km from the 1/2 to zero.

I also have a 911 oil temp/press gauge. When I turn the lights on, oil temp rise and press drop a little. I haven't seen any changes in the fuel gauge, though.

I believe the stock vibrator could make my oil readings stable.
My question is, is there any kind of morden electronics (diodes or whatever) that could replace the vibrator?

Mon Feb 22, 2010 6:16 am

The vibrator is a mechanical voltage regulator. Not sure about VW's but the Mustang I have has a vibrator which lowers the battery voltage from 12 volts to 5 volts for the gauges.

There are electronic voltage regulators whcih do the same thing. They can be purchased at any good electronics store. About the size of a transistor.

Mon Feb 22, 2010 1:33 pm

dkthom7 wrote: Can someone tell me what is the purpose of the vibrator that is attached to the back of the fuel guage?

As someone else has said, it's an electro-mechanical device to stabilize the AVERAGE voltage sent to the fuel gauge. That way, your fuel level doesn't vary between when you're running on battery (as low as 11.5V) and running on the generator (as high as 15V).

I don't know what the effective average voltage is; it might be 5V.

The best answer to your question is to use a gauge and a sender that are designed to work together, and wire them up how they're supposed to be wired up.

If you want to use the Porche gauge with the VW sender, then you'll have to figure out the voltage expected by the gauge and what its upper and lower current limits are, and wire things up so that it matches and won't pull too much current.

Mon Feb 22, 2010 2:18 pm

The vibrator output is 12v

Mon Feb 22, 2010 2:32 pm

Luftgekült wrote: The vibrator output is 12v

But not the AVERAGE output. It outputs whatever voltage is input, but only about one third the time. So the average effective output is in the range of 4 to 5 volts. I just don't happen to know, and I haven't measured it.

Tue Feb 23, 2010 12:46 am

gevmage wrote: Luftgekült wrote: The vibrator output is 12v

But not the AVERAGE output. It outputs whatever voltage is input, but only about one third the time. So the average effective output is in the range of 4 to 5 volts. I just don't happen to know, and I haven't measured it.

You're right

Tue Feb 23, 2010 6:22 am

It's quite easy to replace the vibrator with a solid state 5 volt regulator. They only cost about $1.50 at Radio Shack.

Tue Feb 23, 2010 9:08 am

Like previous post, The vibrator is an elctromechanical voltage regulator - the fuel gauge works on 5 volts.
so, like others mentioned, it is there to reduce the ~12V to 5V by means of duty cycling the 12v ( intermittant on/off) .
it is also true that it is possible to replace it to a solid state 5v regulator.
notice that if you hook the fuel gauge or the fuel sender to 12v you might burn them. both of them are quite sensitive so be careful.

Tue Mar 23, 2010 8:29 pm

FYI - I installed the 914 fuel gauge with the vibrator and the needle would dance between empty and full so I decided to run it without the vibrator. Also, it does not appear to be accurate but it is better than nothing.