I am looking to debounce a momentary pushbutton. I have decided on an SPDT momentary switch with NAND gates. However I am having trouble in selecting the SPDT switch.

It seems as though it should be simple: 3 poles with common, open and closed. However when I look at the switch datasheets they are not like that.

The CK switch NP8 series looks about right. But it has 4 poles, and comes in 3 and 4 wire versions. I don't follow what the 4th pole is for, or the 4 wire version.

If I look at the ATEM IP series, then most are shown with only 2 pins. The ones described as NO look like normal SPST switches, and the ones described as NO/NC look like DPST!

So can anyone suggest which of these would be right for my debouncing circuit?

Thanks,

 

Can you provide part numbers?

 

The ones described as NO look like normal SPST switches, and the ones described as NO/NC look like DPST!

SPDT is what you want.

Something "described as NO/NC look like DPST" would fit this bill.

 

I am looking to debounce a momentary pushbutton. I have decided on an SPDT momentary switch with NAND gates. However I am having trouble in selecting the SPDT switch.

This might work:
http://www.digikey.com/product-detail/en/BB16AP-FB/360-2687-ND/1056530

 

Thanks for the quick replies.

The one I have is the NP Series NP8S2R202GE. The data sheet is here: www.ck-components.com/66840/np_15jan13.pdf/
The schematic on page A124 shows what looks like two options: either a shared common or separate Open/Closed. I assume that means it can be wired up either way. If I wanted the flying lead version then I assume the 3-wire gives me the shared common.

Another one I looked at is the APEM IP Series: http://www.apem.com/files/apem/brochures/switch-pushbutton-IP-mom-ENG.pdf
On page B1-20 it also has two options: either NO or NO/NC. In this case the NO has only two lugs. I assume I would need the IPR5SAD to get a shared common.

 

You can use that 4-pin C&K NP8 switch as shown in the circuit below:

You can choose either 7400 TTL or 4011 CMOS NAND gates depending on the rest of your design.

 

That's excellent, thanks very much. That's exactly what I was hoping to confirm.