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fuel gauges
Aboardman - 9/8/06 at 06:42 AM

looking at some gauges for a mini project and found these

http://cgi.ebay.com/ebaymotors/DOLPHIN-6-PRO-TAN-STREET-ROD-GAUGES-WITH-GOLD-RINGS_W0QQitemZ4583157769QQihZ002QQcategoryZ80739QQssPageNameZWDVWQQrdZ1Q QcmdZViewItem

based on the currant exchange rate of £1-$1.91 that is just over £100 for gauges which i think is a good price, (awaiting cost of postage).

my question is the fuel gauge by using a standard sender unit, this possible may not work right with the gauge, how can you adjust this, is it a case of adding some resistors etc. to alter the voltage back to the gauge.

thanks

02GF74 - 9/8/06 at 07:34 AM

quote:
Originally posted by Aboardman
my question is the fuel gauge by using a standard sender unit, this possible may not work right with the gauge, how can you adjust this, is it a case of adding some resistors etc. to alter the voltage back to the gauge.


I am using defender guages with series senders (landrover).

Now firstly the series sender is designed for a guage that runs of 9V, the defender guage runs on 12 V.

Secondly the series sender works in opposite direction to defender sender i.e. when series sender is empty, defender guage would show full and vice versa.

I wrote all that to illustrate the 2 problems you will face.

... but going back to the first sentence you can see this can be overcome.

I made a small circuit using 2 op amps to firstly compensate for the supply difference and to invert the signal so the gauge follows closer with what is happening in the tank.

Ideally you want to know the supply for the guage and what resistance for full/empty then find a suitable sender otherwise you need in the simplest case, a resistor, worst case some electronics like I have.

It will look like this: (note there are 2 identical circuits with adjustment pots since I have two underseat tanks and twin guages - if you have a v8 in a Land Rover you'd understand why).

Aboardman - 9/8/06 at 07:46 AM

the gauges come with a sender unit but doubt it will fit a mini tank unless i can modify it, but it will be easy to get the resistances.

Danozeman - 9/8/06 at 09:13 AM

U can modify the float arm on alot of senders if they wont fit in your tank.

You may be lucky with your original sender. It may well be the same resistance values as the gauge.