please help a noob with relays?

[lazz]

i know some extremely basic electronics knowledge but i cant seem to find some parts im looking for for a project i have. my project is to turn a weedeater engine to run on compressed air. i have the mechanical stuff figured out but i need to determine what im really looking for on the electrical end. i want to use the voltage from the engine's magneto to power an air solenoid to inject my air but the solenoids i can find run on far more voltage. so anywho onto my question:

the magneto of my engine puts out about 8mV which i believe is dc.
the air solenoids run on 12V dc.
i can connect a battery to get the 12V dc.

i am looking for a relay, correct? i need the 8mV on the actuating side and the 12V on the switch side. is what im looking for possibly a real thing or am i looking for bigfoot? does a relay work like this or is it just for differentiating amperages?

 

[lazz]

i have recently discovered the reed relay/switch. is this more so what i should be looking into? can i use the magnet on my flywheel to operate it and i can just throw out the magneto and just put the 12V to the reed?

 

[shumifan50]

Why so complicated?

You did not say whether the weedeater engine is 2 or 4 stroke.

If you just inject the high pressure air into the intake(made mechanically strong enough to handle the pressure) then you just need to start the motion and the existing mechanics should still work At most it should need retiming the inlet/outlet valves.

In simple terms a relay is just a switch that can be turned on/off with the rated coil voltage of the relay. Your 8mV will be too low to directly drive a relay - you will need some electronics.