reed switch in circular motion detection

[CellarDoor]

I am having a problem with a very simple schematic. Basically the object is a reed switch tracks rotational motion, sending 12V pulses into a simple square to triangle circuit (integrator, rc circuit)driving an led. The problem is the reed doesnt like the cap. When I bypass the cap, circuit works fine as a simple on/off scheme. With the cap in the circuit, the reed switch locks up and has to be smacked a few times to operate. If I remove the reed switch and use a simple spst switch, circuit works how it is supposed to, converting a pulse into a triangle wave. I attempted using diodes in different arrays to isolate the reed switch to no avail.... not sure if it is recieving a drain voltage ect? any help please? I have included the schematic in case needed

or a link to the schem. <a href="

http://n00091.myspace.com/00091/69/28/91878296_m.gif">Square

to Tri</a>

 

[itsmoked]

You shouldn't double post......

The problem for the reed switch is that the cap appears to the reed switch as a dead short everytime it closes! This is welding the reed switch shut. Your regular switch is capable of conducting this surge without welding. Or it may be welding too, but you directly act on the contacts when you flip it.

You need to use either an op amp circuit to do this or a logic chip like a HC14, that is switched by the reed. Use the gate's output for your integrator.

 

[OperaHouse]

You could put a 15 ohm resistor in series with the switch and that would likely prevent the initial surge current from welding the contacts.

 

[CellarDoor]

Thanks ITsmoked, the 15 ohm res. did the trick !

 

[itsmoked]

Good for OperaHouse!