Wanted - Sensor

[RossM]

Does anyone know where where i can get a magnetic sensor?
It needs to be like a magnetic switch that only allows current to flow through when the sensor is aligned with a magnet on the flywheel.
Cheers. Ross

Edit: It only needs to handle a very small current (around 3v)

[Captain Chaos]

its purpose?

[RossM]

RPM for Digatron to work out approximate speed

[Jon Fuller]

Originally posted by PuppiesBalls
Edit: It only needs to handle a very small current (around 3v)

Just for the record, 'current' is measured in Amps, it's the 'potential difference' that's measured in Volts

[RossM]

Originally posted by Jon Fuller
Just for the record, 'current' is measured in Amps, it's the 'potential difference' that's measured in Volts

Well its the current of 2 AAA batteries

[Burty]

Why?
my digatron tells me rpm and i didnt need the switch on the flywheel

[RossM]

Its for the speedo, not the tach

[Burty]

when i had a chat with the technical guy at digatron last week he said unless you have no alternative then dont try and get a tach reading from the plug lead as it takes ages to make it work and they arnt that accurate.
he said ideally you want a ground and a 12volt square wave output

[Burty]

Originally posted by PuppiesBalls
Its for the speedo, not the tach

nobba. whats the point in editing your post after someone has replied cus then it dont make sense????

anyway how can it tell speed from the flywheel???
what about gear ratio
prop size
drag
slip?

[JamesM]

Originally posted by PuppiesBalls
Well its the current of 2 AAA batteries

And how much is that? The current output of a battery depends on its source impedance and the load placed on it so you cant just say its the current of 2 AAA batteries cus that doesn't mean anything.

[JamesM]

Originally posted by Jon Fuller
Just for the record, 'current' is measured in Amps, it's the 'potential difference' that's measured in Volts

EMF (Electromotive Force) is also measured in volts.

Kirchoffs second law (voltage law) states that the algebraic sum of the EMF's in a closed loop must equal the algebraic sum of the PD's

[JamesM]

Originally posted by PuppiesBalls
Does anyone know where where i can get a magnetic sensor?
It needs to be like a magnetic switch that only allows current to flow through when the sensor is aligned with a magnet on the flywheel.
Cheers. Ross

http://rswww.com/cgi-bin/bv/rswww/home.do?cacheID=ukie

Do a search for 'reed switch'

[RossM]

Cheers