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suprant0010
#6
Jul20-10, 07:02 PM
P: 7
Quote Quote by berkeman View Post
I'm surprised the wiki page says that reeds are used on some bike computer pickups -- I think the speed and wearout limitations would preclude them from that application.

If the speed of the rotating object can be slow sometimes, then you should use a Hall effect sensor to detect the passing magnet. Yes, you will need a small amount of circuitry to convert that signal into whatever you need to drive your solenoid.

If the speed is always pretty fast, then all you need is a small coil to pick up the voltage from the passing magnet. Again, you will need a small amount of circuitry to convert this voltage pulse into the signal to drive your solenoid.
speed is going to remain a constant, at least at this stage of the project...so no need to worry about changes in pulse width

i was hoping to keep things as simple as possible, seeing as how my knowledge of circuitry is very limited...if possible i wanted the pickup, whether it be a reed or some other type of switch, to close the circuit that activates solenoid directly

the solenoid im using only takes 0.8 amps at 12v DC, im seeing plenty of reed switches that can handle 1 amp...it seems to be a good route to take, my only concern being how long they will last under these conditions

Quote Quote by dlgoff View Post
Welcome to PF suprant0010. Have you considered doing it optically? Here's a little DIY kit that may give you some ideas for your project.
K8092 - Optical Proximity Switch Kit
interesting...the only problem i see with it is it says that its not intended for dark areas, my project is enclosed in a housing and will be completely dark inside