pir/timer help

shrtcirkt

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Hello Everyone, hope you all dont get too tired of all us newbies with questions, but here is my problem.
I've been reading all the posts while putting together a cam and have found answers to all my questions until now.
I have a PIR from Amazon electronics, the one with only 3 wires, positive, ground and output and I am trying to use it with one of Joe D's timers. Joes timer works great and so does the PIR, until I connect them together. I am connecting the output of the PIR to the positive side of the relay coil and the negative side to the common side of the timer circuit, (when this relay closes it is supposed to pull down pin 4 and start the time cycle) when I do, nothing works. The relays have diodes across the coils, but should I isolate the power to the PIR somehow? maybe diodes?
One thing I did notice is that when the PIR is connected in the circuit the output seems to be a negative signal instead of a positive. Does this make any sense?
Any help would be greatly appreciated, this camera is ready to go except for this problem :(
Thanks for the great site and all the help.
 



Tinhorn

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I'm a little unclear about how it's hooked up but sounds like you have a relay between the PIR and the JoeD Timer trigger pin?

I don't think that's necessary:

1st
have a common battery provide power for both the timer and PIR

2nd  (ONLY if you have a common battery do this!)
connect the PIR Output directly to JoeD's Timer Trigger Pin 4 (is it?)
(assuming the voltage on the PIR output goes from Battery (+) to zero volts, or close to it, like you said)

3rd
thats it,  connect a relay to JoeD Timers Output pins as he shows in his plans etc and you should be set

If something above is not true, post what is what and we'll try again.  I don't know what volts the PIR runs on and a common battery maybe a problem....

Here is what you were trying to do I think, which will work:



Tinhorn
 

shrtcirkt

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Tinhorn, thanks for the reply, here is a schematic of the timerand PIR as I have them wired. I assumed that the relays on JoeD's print were for the NO contacts which would close when energized to pull pin 4 low. I tried wiring my PIR output right to pin 4 and still no luck.
The led's are for the timer and counter display, and the switches are for setting the timer and reading the counter.
If I pull the pir out of the circuit and connect a LED to the output it works fine, cycles on and off as it should. if I leave the pir out and jumper across the contacts of K1 the timer works perfect. It is only when I add the PIR that I have a problem?
if I scratch my head on this one any more I am gonna lose the rest of my hair.

The timer and Pir use the same voltage so I am using a common battery. Something tells me that I am missing something reletively simple, What do you think
 

Tinhorn

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Well, I think I see the problem, we "both" have one end of the relay coil connected to the PIR output and the other coil end going to "Ground".  Instead of Ground (Batt (-)) that end of the relay coil should be connected to batt (+)

Because

when the PIR senses motion, It's Output goes Negative (ground), when it goes Negative (zero voltage) then (+) flows thru the coil, closing the contacts

but, funny, It looks like to me the trigger relay is NOT needed, the PIR Output going to Negative should be enough to trigger JoeD's timer????

(those are REED relays right?, just checking, any other mite draw too much current and not work)

IMPORTANT, also, reverse the diode going across the relay coils so that the BANDED end goes to the most Positive end of the relay coil (in other words, the banded end connects to Batt (+))

Tinhorn

 

ONESHOT

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I think you're right Tinhorn, but since he already tried the pir output directly to pin 4, maybe the relay is required to get a true (-) reference on pin 4.
 

shrtcirkt

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the Saga continues....
ok, here is what I tried this morning(started at 5am)
I reconnected the PIR with the output to pin 4, It triggered one time then would not trigger again, so I set up a test circuit. I wired the pir to a reed relay and put my meter across the contacts, I wired the output to the + side of the coil, bat + to the +of the PIR, and the - side ofthe battery to the -side of the pir and the - side of the relay coil.
Connected like this the circuit works perfectly. I then diconnected the - side of the coil from the - bat and connected it to the + bat/PIR connection. Again the circuit worked, except in reverse. The relay contacts stayed closed until the PIR deteced movement, then the contacts opened.
I guess this means depending on how the PIR output and coil are wired you can make this either a sense to make or a sense to break circuit.
But when I wired it back to the timer it still would not function.
Does this make any sense?
I suppose i could wire in seperate battery packs for the PIR and the timer, but it seems that should be unneccesary and bulky.
Would diodes installed in the power circuit be of any help? If so how would you install them?
Thanks for the patience :)
 

shrtcirkt

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The latest,
I went ahead and wired in a dual battery pack, 1 for the timer, 1 for the PIR. I used the PIR (reed) relay to bring pin 4 low.
Running the dual 3AA battery packs everything works great. JoeD's timer is really a nice unit.
Now I am wondering whether the single 3AA battery pack is enough? At least with the dual battery pack i should get plenty of battery life But I still would like to get this down to one bat pack. What about 4 'C' cells?
 

Tinhorn

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I hope you are "BreadBoarding" this somehow and not soldering/unsoldering every time   :)

I'm not familiar with the PIR u r using, what voltage does it require (and do you know how much current it uses) ?  just curious

As long as the PIR and JoeD's timer run on the same voltage, one battery pack will run it (how long depends on the current of the PIR because JoeD's Timer's current requrements is very low) but it will definitly run more than the 1 minute u r getting!  and I'm sure it will run for weeks.....Also, just a note, we don't want to run it (anything) with the relay "pulled in" because it would run down the battery's pretty fast.  At idle, we want the relays to be in "Bench" Condition......

I think you are very close to getting this thing right and it won't be long now!

Let's get real BASIC for a second, we are missing something simple here.

1st, looking at the Sketch JoeD made for his timer, he's not clearly noted that the reed Relay he has shown connected to pin 4 means the "Contact" of that relay get connected to Pin 4 and the other contact gets connected to batt (-)  

The relay coil gets connected to the PIR output but the other end of that coil can either be connected to batt (-) or Batt(+) depending on what teh PIR output does when it's triggered by motion.  At first I thought you meant that output went from Batt(+) to zero volts when the PIR sensed motion but now, after reading what you just said, I'm not so sure.

What we want is the relay to be connected to the PIR and be at Bench Condition when the PIR is NOT sensing motion.  Bench Condition in this case means the contacts are OPEN

so, just to get this part rite, put your meter on OHMS and check continuity of the contacts when the relay coil is connected to the PIR.  with no motion (after teh warmup period all PIR's have) you should see the meter NOT move......if it deflects then reverse the coil wire connected to the battery (swop to (+) or (-) whatever the case is)

This post I just made is getting pretty long but I bet you find the problem soon........

I just looked at the 1st sketch you posted and it looks like it should work that way except the coil wire on the opposite side of the PIR Output may need to be connected to batt (+) instead of batt (-) (again, depending on what the PIR output voltage is when it does not sense motion)

Good Luck, again   ha ha

Tinhorn
 

shrtcirkt

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Well, I got it.... finally...I think.
I rewired everything, only this timeI brought power in straight from the battery posts to the PIR and the Timer. Worksfine like this using one battery pack. I am going to assemble this cam as is( i want to get this out there) and then play with the circuit on the bread board some more. I am sure the problem had something to do with the way I wired the power circuit between the PIR and timer. I'll let you all know if I find anything definitive.
Thanks for the help, especially to you Tinhorn.
Now.... hopefully, soon I'll get some pics up.
 

Tinhorn

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ShrtCirkt

You forced me to breadboard JoeD's timer   (Ha Ha) and I added a Report of what I found under that topic.

You might be interested in how the PIR is connected to pin 4

Tinhorn

BTW,  I liked your Movie, Short Circuit      ;)
 


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