Finally got a 2 stage timer installed!

Matt in MO

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Whew! It took me all summer thinking about it but I finally got a 2 stage timer stuffed into the Pelican 1120 along with the RS PIR and Canon PF. I've been satisfied with the previous results but wanted to get to the "higher level" of homebrew cams. Before I would get several photos of each deer - which at times is good.

I have found that as long as the trigger to ground is engaged (the RS PIR is sending power to pin2 which is powering the trigger's relay), the second stage will not time out. Thus if something walks in circles in front of the cam forever there will never be a second photo (my knee hurts, theres a worn spot in the carpet and my kids think I'm nuts!) Is this quirk a feature of the design (tinhorn's first version) (is there a work-around?) or do I have an error in assembly? I'm currently triggering to the RS PIR ground rather than the timer board ground.
 



Tinhorn

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Matt

I see you're still having trouble with that dumb ole trigger problem.....Darn

It's the nature of all 555 type timers to stay triggered as long the trigger  signal remains on pin 2 but, like you said, we don't want that.

Thats the reason C1 (.0047 or .005) is required.  It blocks all "continuous" DC signal volts except when the PIR signal "1st" arrives, a very short pulse does pass thru C1 & trips the 555 timer.  This short pulse would not even register on your volt meter, it's so short (fast).

This pulse that does get thru is not very powerfull so we need R2 & R4 (47K) to be in the circuit to get timer's pin 2 very close to the trigger threshold.  

Caps will retain a charge for a while (stay charged with the trigger volts) so R1 (1 meg) is required to drain off this charge.  1 meg is a very hi resistance, close to not even being in the circuit in this case.  Any voltage that does leak thru the resister is over come by the R2/R4 pair.

SO

to trouble shoot, 1st measure pin 2 volts by connecting the meter black lead to batt (-) & the red lead to pin 2. (it will trip the timer. ignore)  this volts should be a steady 1/2 of batt volts......if not, check R2/R4

Be Sure R1 is 1 meg, this is important too, if these are ok and I'm sure you double checked your wiring a hunnert times, then C1 must be bad (shorted)

hope you find the culpret

Tinhorn
 

Matt in MO

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Thanks tinny, I've printed your post out and will beat that timer into submission!
 

Matt in MO

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Well... in checking pin 2 voltage, I have 1/2 battery voltage at the 2nd stage 555 (the delay) but only .4 volts at the two second stage 555. Checked the 47K and 1M resistors, then ran to RS and bought new TLC555s (now std. 555) and new .0047 caps. When the TLC555 are used the circuit is in a "Do Loop"  where it triggers itself, thus a nice blinking light toy. Went back to the std 555s. Wondering if the problem is my voltage - I'm using a 9V transistor battery to power the timer circuit. Should I have made some adjustments to use 9V? I see your newer version shows 6 volts.
 

Tinhorn

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Matt

6 & 9 volts aren't the problem (I don't think)  

555's are notorious for creating it's own "false" trigger problems because of a voltage spike in the power supply when they change state (sudden rush of current draw does this)   The Standard 555's draw more current and are bad about this but TLC's draw about 10 times less current and usually have no problems.

When you had the "Do Loop" going, I think the circuit was all ok as far as construction is concerned but the circuit was triggering itself thru the power supply for some reason.  

Try this:
install a 100 - 200 uf cap across the batt (+) & (-)  as close as you can get to one of the TLC555's (pin 1 & 8 maybe)

then also Install a  .1 (that's point one) uf cap in parallel with the 100 - 200 cap.

These might ground out the crow-bar pulses causing the problem

Also, this might seem strange that it would work, but try the circuit with the Arm Switch in the relay position rather than the LED test position and see if it works,  I remember once the LED itself was somehow false triggering the circuit, when it was removed (by the switch set to relay), the circuit timed just fine. (?)

Tinhorn
 

Matt in MO

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the 100-200 uf across pin 8 and pin1 one - that's the same as C7 which is already there - try adding another near the other 555?
 

Tinhorn

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Man, I forgot it was already there and didn't even check - - - sorry-bought that - - -

but I know there ain't a .1 shown, so add it nd see what happens.  I don't think adding another will help but you never know.

Don't forget to try it without the 2 min test LED energized but I hope the .1 fixes it.

Tinhorn
 

Tinhorn

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Matt,

Good News!

I did some "bread Boarding" over the w/e and got a setup to toggle like you said (the Do-Loop Thing)

Everything worked fine on the 2 stage timer until I connected the PIR - then the Toggling Started, something was apparently triggering the PIR (in my case, in yours it could be triggering one of the timer stages)

and I found the culpret was the 2 min Test "LED" itself, when the stage timed out and shut off the LED, it apparently created a pulse that triggered the PIR

This LED was a Green one, the 2 sec stage was a RED one, I'm wondering if Green had anything to do with it since the Red LED didn't create any problems

Anyway, I put a plain ole diode in series with the LED (banded end facing away from the Pin 3 connection and this stopped the problem.  (in other words, the diode Cathode was connected directly to the LED Anode)

Some relays require this diode setup to prevent a pulse from backing up into Pin 3 and false triggering the timer stage but I never heard of an LED doing it.

At any rate, if you haven't put a 357 bullet hole thru your timer yet, try the diode trick and let me know for future reference

Thanx

Tinhorn

(Edited by Tinhorn at 10:47 pm on Aug. 26, 2001)
 

Matt in MO

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Thanks Tinhorn - I'll try that. I did leave the camera in the woods w/o the timer - its a two hour drive so I won't get it back until this weekend. I'll do testing with a new RS unit and just a plain 6 volt input (two more cams are in the works). I did try cutting out both LEDs, adding the 0.1 cap, etc etc. I tried so many "trial and error" things I need to go back to square one and take a deep breath before I do the "postal" thing! There were things going on that just didn't make sense. Do you recommend your second version timer over the first version

ugh. turning 40 today.
 

Tinhorn

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Hi Matt, happy BD, when I turned 40 my Mother said I could quit having them but it didn't work.....

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I think the 2nd version is more stable alright (Long timer stage triggered by the PIR)  I'm guessing I have built 20 - 2 stage timers, all but 3 or 4 were the 2nd version and I have never had any problems out of the 2nd version.  That's one reason I have been "Promoting" it on the Forum, I've always felt more comfortable with it.

As far as that goes tho, I've only heard of very few problems with the 1st version and have had trouble duplicating problems when bread boarding it.  Sometimes I wondered if the problems were Lead Dress (the way the wires were run) but now am thinking it may have been LED's all along.  I wish I had paid attention to LED "Color"s when I tried to duplicate a problem, I'm wondering if Green or Yellow LED's are "Dirtier" than Red!  I always just grab one out of my Junk Box and ignored colors for the most part.  The question is, why don't I have any problems with the Dirty LED's (?) in my 2ns version?  I don't know, never have tho....

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You're probably noticed I've used the 2nd version quite a while so why the 1st version?

A little History on how the 1st stage came about.  

When I 1st found the Tenn Forum Site, they were all trying to figure out a 2 stage timer and making pretty good prograss, their therory looked good.  Jesse (& probably others) was playing around with a relay to somehow interupt the PIR signal from reaching the Shutter Timer Stage or maybe even turning off the shutter stage somehow, for 1 or 2 min's, to create the delay between pix's.

Altho I had been using the "2nd" version for several years in a camera I now call Old Ponderous, their theory sounded interesting and I came up with the 1st version, using a transistor to turn off the Shutter Stage.  I like to tinker with electronics and just came up with the circuit because it was new and different than what i'd been using on old Ponderous.  The parts components were the same, only arranged differerntly was all.  (I also wanted the parts to be "Off the Shelf" from Radio Shack, easy for everybody to get, and replace when boo-boo's occured)

At any rate, the New Version ended up on Jesse's site for the PF's and the 2nd version was/is on there too, for the Solonoid Cams....

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My 1st cam was built around the 1st version (that you are having trouble with) and it's out in the woods now, no problems, but after that I went back to the 2nd version, just because I was more comfortable with it and I had the circuit memorized too :D

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Well, that was a long post, just to wish you a happy BD and to say, "Yes, I (now) think the 2nd version is more stable"   (of course, my posts are all kind of long aren't they)

Tinhorn
 

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