Large Model Association Forum

Hello,

I want to make my own fuel pump. I would like the box to have an On - Off Switch and a fill and drain switch. I can work out the Off/On switch but can't work out the fill empty.

Can anyone help me on this?

Many thanks

Rob

You need a double pole double throw switch with a centre off position. Maplins will sell them.A slide or toggle switch dependant on your preference. Looking at the rear of the switch there will be 6 terminals set out in 3 sets of 2. The centre set of two is where you want to connect your 12v supply. Pos on one terminal and neg on the other. Now looking at the top set of terminals connect one wire to each. Then with the free ends cross them over and connect to the bottom terminals . Now also from this last connection connect your pump.
When the switch is the centre nothing happens , when it is moved one way it will power the pump with the polarity one way and when switched the other way the polarity to the pump will be reversed.
Hope that makes sense.
Don't forget an in line fuse as well.

Simon

Thank you so much! I will get down to napkins tomorrow ... Will let you know how I go on.

Many thanks again!!

Rob

Here you go Rob.


ON-OFF-ON
DPDT Centre Off
A special version of the standard SPDT switch. It has a third switching position in the centre which is off. This can be very useful for motor control because you have forward, off and reverse positions. Momentary (ON)-OFF-(ON) versions are also available where the switch returns to the central off position when released.

seeing as petrol gives off inflammable fumes, what type of motors should we be looking at so we dont end up barbecued?

The answer to that is easy Alan. Glow motors. I wouldn't use an electric fuel pump unless the pump was driven by
a motor which used no commutator. The last thing we want is sparking brushes. and even with the non sparking motor the switch should be very remote from the pump. Robert didn't mention the type of fuel that he is going to use by the way.