# Voltage Controlled Switch

Discussion in 'The Projects Forum' started by brighteyes, Dec 29, 2009.

1. ### brighteyes Thread Starter New Member

Dec 29, 2009
4
0
Guys

Was wondering if someone could help me with a small project.

I'm after something that will allow me to control (open or close) an output based on an input voltage taken from a Gear Position sensor on a motorcycle (0v to 5v) i.e. neutal=0.5v, 1st=1.1v, 2nd=2v, 3rd=2.7v, 4th=3.5v, 5th=4.1v and 6th=4.7v)
Otherwards turn on when voltage is between 0V and 3V and off up to 5V.
(On for 1st, 2nd & 3rd and off on 4th, 5th and 6th)

I'm a bit rusty but something tells me I simply need a zener diode to allow a voltage connected to an operational amplifer?

Also, what if I wanted to switch the output on for 4th i.e. variable resistance?

Thanks

Pete

2. ### mik3 Senior Member

Feb 4, 2008
4,846
63
You can use a comparator circuit with an op amp and a pot to adjust it at what gear (voltage) the comparator will output high.

3. ### brighteyes Thread Starter New Member

Dec 29, 2009
4
0
Thanks buddy

Is it possible to purchase these off the shelf?

Regards
Pete

Feb 4, 2008
4,846
63

Dec 29, 2009
4
0
Thanks Mik3

Pete

6. ### brighteyes Thread Starter New Member

Dec 29, 2009
4
0
Mik3

I assume it works by comparing the voltage and then producing an output voltage itself? Or will it simply open and close a circuit as an output?
I need the output of the circuit to close a circuit like a relay? I was planning to connect this device between the signal wire etc

Thanks

Pete

7. ### mik3 Senior Member

Feb 4, 2008
4,846
63
You can activate a relay but the output current capacity of a comparator IC is not enough to drive a relay directly, thus you need to use a transistor to increase the output current capability of the IC.