Switching in a sequence

[aaalll7]

Hello,

My first post here.

I'm working on a project where I am looking for a circuit which is triggered by a PIR which is connected to a sequence of contacts 1, 2, 3, 4...

I've been trying to work out a relay based solution, but I've hit a dead end with my knowledge, there may be a much better simpler rsolution so hopefully someone will be able to point me in the right direction.

Each time the PIR is triggered the contact moves on in numerical order.

ie
PIR triggered then contact 1 closes (others open)
PIR off
PIR triggers then contact 2 closes (others open)
PIR off
PIR triggers then contact 3 closes (others open)
...etc...

I hope that makes sense!

Thanks in advance for your help.

aaalll

 

[ronsimpson]

There are two ICs that 'ripple count' CD4017 and CD4022 (MC14017, MC14022). Here is a page from the data sheet. The PIR could drive the CLOCK pin. Your 4 outputs are "0,1,2,3" If you want it to loop on 4 counts then tie output "4" to the reset pin. Every time 4 is high the part will reset back to "0" with out a clock. (very fast)

The rising edge of CLOCK advances the count.

 

[aaalll7]

Thanks Ron that's great!
Seems like it will solve what I need in a simple way. I'll get one of the chips and try it out.
Al

 

[MikeMl]

Note that the clock signal to the 4017 must be "clean" (no extra edges), otherwise the counter will advance multiple times. The 4017 normally has ten states, but you can wire it to skip extra states, for example reset back to state 1 after reaching the sixth state...

Since the 4017 is a CMOS chip and cannot drive much current, I can almost anticipate your next question: "How do I drive a relay or other load"?

 

[Mike_2545]

I think you can do it with relays.

I got that image from: https://www.pcsilencioso.com/cpemma/flipflop.html

 

[aaalll7]

Thanks MikeMI and Mike 2545!

MikeMI: yes you're right that would be my next question, my work around was going to be use relays that only need a low current to trigger to step up if I need greater current. I've got a number of projects where this may be useful, but the first instance is actually for triggering a switch to activate another piece of kit.

Mike 2545: This looks interesting, I'm going to dig out some 3 pole relays and give this a go as well.