Reed Switch Question

[b_reagle]

I would like to know the part number for a magnetic reed switch that handles around 20mA.

 

[Mikebits]

Not sure exactly what your requirements are but 20ma is just a fart in a hurricane. Most reed switches would handle that.
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=59045-010-ND

For other parts, just enter reed switch in the parts search box. Boo-koo selections
http://www.digikey.com/

 

[b_reagle]

I would also like to know if this is a good way of sensing an object. Here is the circuit.

 

[Mikebits]

Sure, magnets are a good way to flip a reed switch.

Well looking at a typical reed switch data sheet
**broken link removed**

they do seem to have bounce issues which may cause an input to your gate as shown in attached photo. This may present a problem depending on what your gate is driving like a flipflop, again may not.

If you wish to eliminate switch bounce issues read here.

**broken link removed**

 

[b_reagle]

The gate runs a MOSFET which runs a motor. Can bounce be acceptable? The magnet is on the door jam and the switch is on the front door. Door is either open or shut, and I don't think it will be an issue.

 

[Mikebits]

The gate runs a MOSFET which runs a motor. Can bounce be acceptable? The magnet is on the door jam and the switch is on the front door. Door is either open or shut, and I don't think it will be an issue.

The bounce should not be a big deal in such a case. But I do have concern about undershoot blowing your gates input. To be safe, I would add a RC shunt to ground on the gate. See image.

 

[b_reagle]

I have an x-tra D Flip Flop (1/2 74HC74). I think there is a way to use it. Is that 10k and 110 ohm's for the R's. Thanks

 

[b_reagle]

Does this circuit need R1?

 

[Mikebits]

R1 and C1 is what I am talking about. They make up a filter and will reduce poop on your gates input Back in my design days, I would use that configuration a lot as a precaution.
You can ignore the rest of my circuit as I only meant to show the filter...

 

[b_reagle]

Sounds good. Will it work 6vdc to 3 vdc. If so how do you determine R1's and C1's values?

 

[b_reagle]

Is this a good way of eliminating bounce in the switch? Are the R's the right value? Or am I going about it all wrong?

 

[ericgibbs]

Is this a good way of eliminating bounce in the switch? Are the R's the right value? Or am I going about it all wrong?

hi,
OK, You should also ground 11/12 pins

I assume the resistors are pullups to +V.?

 

[b_reagle]

Hi,
Yes, R's are used for pullups.
Thanks