MS20 re-trigger

ArkansasElkHunter

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Has anyone ever tried to figure out how to make the ms20 where it would re-trigger even if it was still sensing motion like the RS PIR.  

I went and picked up a camera today that was in a friends backyard.  He has flocks of 30+ turkeys every morning.  He gave me a vidio of the Toms strutting in front of my camera.  There were only 5 pic on the camera.  I put it back in picture mode and walked across in front at 35 feet and snap it got me.  I'm sure it was the constant motion keeping it from taking a pic.

Brian.  Could there be a simple circuit added to your timer to compensate for this.  


I know that it could be handy on a bait pile, but I hate to miss the strutting!
 



Brian

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I am afraid it is built into the MS20 and the timer can't help.  The circuit would have to be hacked and changed to fix this.  Tinhorn might know how since most of the circuits I have seen have come from him.  I have never used the MS20 myself.
 

Tinhorn

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ArkansasElkHunter,

Do (did) you have the MS20 slide switch in "Test" mode?  

Test Mode resets in 4 seconds but will "not" reset if there is movement before 4 seconds is up (in "Auto" mode, instead of 4 seconds, it's 1-1/2 Min's)  I guess there could be constant motion when it's several turkeys in front of the camera, even when the slide switch is in TEST mode.......

Are you sure you want the camera to rip off the whole roll of film when I flock of Turks walk in?

If you have a timer, I think you could reduce R26 (33K) to maybe 1K.  This would change the 4 sec time to way less than a second but a timer would still see the trigger pulse.  It'd be unlikely to be reset by a flock of turks that way.  You can't do this with out a timer because the shutter would not be held in long enough to snap a pix.

Tinhorn
 

ArkansasElkHunter

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Thanks Guys.

Tinhorn, thats just what I wanted to hear... simple, cheap and easy.   It was in test mode.   And yes there were 36 birds in the video he gave me.  I know you wouldnt want it all the time.  

I run brians timer so I can limit the pics to from 10 sec to 25 min.  I would just like to be the one deciding how many pics, not the animals.  I'll try a 1k and test it out on the bench.  Sounds like that may be the perfect solution for what I'm after.

Brian, How does the chip control the test mode LED time.  With a milisecond pulse from the PIR will the LED stay on long enough to see.  I'm almost sure it is controlled by internal timing on the chip, just thought I'd ask.  Is there a limit on the signal time from the PIR i need to watch out for.

Thanks again
 

(Edited by ArkansasElkHunter at 11:08 pm on April 7, 2002)
 

ArkansasElkHunter

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I put in a 1K resistor for R26 like tinhorn suggested.  The time to reset is still just over a second but much better than 4 sec like before.  I tried a 470 ohm and a 180 ohm as well to try and get below a second, but the sensor seemed to become unstable.  It would trigger randomly.  I'm sure I was keeping all motion away from the sensor, but I can't explain it any other way.  It would reset but not a whole lot quicker than with the 1K so I wen't back to it.  I will let it set overnite and let brians timers event counter tell me if there are any false triggers.  I was able to walk in front of the sensor and sometimes get two to three triggers while in the FOV.  I use brians timer so I can set the delay when I don't want a bunch of pics of the same animals.  


Tinhorn,
Thanks for the help.   What value for R25 would give the same 4 sec delas as the original R26. 33K or are the caps different?    If I could reduce it as well I could just switch back and forth between the modes and choose if I wanted constant motion to prevent additional pics or not.  Seems like maybe the bestof both worlds.

thanks again
 

Brian

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ArkansasElkHunter,

The LED will stay on the same amount of time 500milliseconds no matter how fast you try to trigger the chip because I can no longer monitory the PIR while turning the LED on and off.  Once the LED goes off the PIR trigger is monitored again and the LED will turn on and off again.  OVer and over until you take it out of LED test mode.  THis is not an interrupt driven routine just a monitoring of the PIR pin.
 

Tinhorn

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ArkansasElkHunter,

R25 and R26 both use the same timing cap, as you suspected (C13, 22uf).  The Test/Auto switch just connects one of the resistors to the Timing Cap, depending on it's position.  This switch also is suspose to defeat/undefeat the DayLight Sensor but it don't do anything since the sensor has been removed (right?)

I can see where reducing the resistor closer to zero ohms might cause problems because it would be shorting the PIR signal to ground....U might try removing C13 and see what happens.  Probably the resistance thru the IC itelf was causing the 1 second delay when you reduced the resistance below 1K.  Without the cap, there'd be no or little delay at all then, I don't think but I'm sure Brian's Timer would still detect the fast trigger pulse.

I install the MS20 so that I have access to the Auto/Test switch and can use that feature you mentioned when I want too.....

Tinhorn
 

ArkansasElkHunter

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Tinhorn, Brian,

Yes, no Light sensor - Just like your timer mods in brians doc.

I was trying to monitor the voltage and watch the light blink to determine when the PIR was triggered.  I may be possible that it was triggering faster than I was able to catch.  The meter takes a second or so to change voltages so I was relying on the light to tell me when it triggered.  
 

Brian

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Yes the trigger can be a lot faster than a meter can capture it. If you have the fluke 87 meter you can use the high low feature and it will capture it even though you cannot see it happen.

Don't hold me to this but from looking at the manual some more I think I found where the pulse width of the trigger pin can not be any shorter than 25uS so you should be fine and then some.
This part of the manual is not that clear to me.  It states to find this time look at the AC charateristics and I can't find them in the manual but I haven't searched it from top to bottom yet either.
 


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