Strange MS20 Sensors

Welby

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Right now, at my desk, I am playing with a camera I built for someone else.  This particular unit consists of a MS20 PIR, a TLC555 One Shot 15 Second Timer with a 9V Relay, a test LED and Powersonic PS1212 Battery.  What is so bizarre about this particular camera is that when I turn it on, two things happen (or rather don't happen) that get my attention.  

First, there is no thirty second warmup, only a ten second warmup.  Second, this MS20 does not trigger the Timer/Relay upon warmup.  It only trips the Timer and Relay when the PIR is triggered in normal use, or when actual motion is detected.

Make no mistake, I am not complaining about this behavior, but it does make me wonder if they are making the MS20's slightly different now.  The reason I wonder this is because I know that when we first started using the MS20 as a PIR for camera use, not only did it have a full thirty second initial warmup, but it also would trigger the Timer and Relay when you turned it on.  I know this because I would have to wait a full thirty seconds before turning on the switch that would arm my camera.  Also, the first MS20 I modified had a full two minute delay in the Auto setting.  Similar performance figures were reported by many other camera builders as well.

However, the past two or three cameras I have built using this combo have yielded different performance results.  Ten second warmups are now the norm.  Two minutes in the Auto setting is now one minute thirty seconds.  And, on this particular unit, no triggering of the Timer/Relay upon warmup.

I guess what I am really asking here is this:  Are any of you getting these "new" results?  If so, is it because the MS20 has been changed or is it because we are doing something different?  Finally, if I am the only one getting these results, am I possibly looking at a troubled and doomed MS20?
 

gizz

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Funny you mention it!. I just tore one apart that appeared to NOT be working. It would trigger the relay as normal but not long enough for the camera to take a pic. After messing with it I realized that it did not have the 30 second warmup - hmmmm. I ended up replacing R26 ( i believe that's the one for "test" mode) with a 120K resistor to hold the relay closed for 10 seconds. It now works and I put it all back together. It is MS20(New mainstay), Owl pf, NO TIMER, 1212 battery.

I guess what I'm saying Welby is that you may be on to something there. It could explain the unusual behavior I've had with these last 2 cams I built in the spring. I've replaced the relay on the other one 2 times thinking it was the problem and maybe, just maybe, it needs the resistor swap as well. It seems to "work" but I don't get the pics that I think i should be getting and SOMETIMES the camera doesn't fire although the LED does.....geeeeez, now I'm getting all flustered. :banghead:

If'n I find anything out I'll let you know.
 

jayber

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Are the MS20 model numbers still the same on these units that are acting differently?
 

Tinhorn

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Man, I spent hours (actually several days) reverse engineering the MS20 and creating a schematic    :confused-yellow:

Somebody else can do it this time,  ha ha

Actually, I've not noticed any differences but have 2 "Spares" and will check them out.  I'm so used to the 30 second warmup period I may have never noticed any change on the last few I've built.

As far as the Auto Delay being 1 min 30 seconds, all of mine have been that way, even from the beginning......

See Ya!

Tinhorn
 

gizz

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I just tore into a BRAND NEW mainstay and it seems OK as far as the warmup is concerned. I've been removing some "excess" stuff from the MS20's for a while now. I'll remove pieces one by one from this spare and keep checking. Maybe one of them somehow makes a difference?? Maybe Welby and I are doing something different than what we used to do. Maybe I should re-read the directions for the MS20?

BTW, the boards are marked MS20 so I just find it a little hard to believe that they are different. We'll see.
 

gizz

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OK, I've had a mainstay ms20/owl pf hooked up for 2 days now and everything seems to be working without any problems. I soldered in a 100k resistor to the "test" circuit to give a longer delay cause my owl pf wasn't firing all the time. I'm NOT having the short warmup with this mainstay PIR so I'm now wondering if maybe I messed up the other one somehow. I guess what I'm saying is that it may be a "bad" MS20 - (probably cause i messed it up somehow). I'm having NO PROBLEMS with the newly modified one.
How bout you Welby? Have you found anything else out yet? I'd like to find out what's up with the short warmup delay on the MS20 but I'm not sure what even causes the "warmup". Maybe something got shorted on the board and you and i both did the same thing??

Oh, BTW, strange "things" only happen on the cams you build for someone else. :roll-wink-green:

(Edited by gizz at 9:31 pm on Nov. 23, 2001)
 

gtk

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Hi Gizz.. When you say

" I soldered in a 100k resistor to the test circuit to give a longer delay cause my owl pf wasn't firing all the time"

Is that because the charge is leaking out of the capsitor ?  Sometimes I have to trip my cameral twice before it will take a pic, after it has set idle a long time.

If that's the problem your talking about, tell me what to replace, and with what.. I have that problem with several cams.

Thanks for your work on this stuff...
 

gizz

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Hi gtk - I have some owl pf's that take a little while to fire(This has been covered by Arch and Tinhorn on several threads). Since I'm lazy and don't want to build a refresh circuit I just replace "R26" (resistor 26) on the MS20 board from a 33K resistor to a higher value, say 100K or 120K (whatever I have laying around). This gives me a longer close time on the owl pf contacts so that the picture goes off.

You can test to see how much longer you need the contacts closed by leaving the camera "on" for a day or two then touch the 2 camera wires together and see how long it takes to fire the camera. Here are the different resistors I've tried in R26 on the MS20 board:
I found that for every 80k or so that you increase this resistor(R26) you gain about 3 to 4 seconds in test mode. Here's what I've tried:
100k = 8 seconds
180k = 12 seconds
270k = 16 seconds

The initial values for the MS20 are:
R25 (2.2M) is used for Auto Timing
R26 (33K) is used for Test Timing
 

Welby

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Thanks for the responses.

Unfortunately, I know just enough to be dangerous and not enough to do any serious troubleshooting on the MS20.  I have been wiring my newest cams just like Tinhorn, with the exception that I use a single stage timer in place of his two stage one.  I remove all unnecessary parts on the MS20 like he illustrated.

I timed my first cam, which just had the blue relay and no timer, and it was a full thirty seconds on warmup and a full two minutes on the Auto setting.  But, my latest creations all have ten second warmups and ninety seconds on the Auto setting.

But, they work fine and I'm not complaining....


...except about those two MS20's that went psycho on me.  On one, it would start  triggering and resetting constantly, slowly at first then faster and faster until it would just lock up.  The second psycho PIR would never reset after you turned it on.  

Guess I have that effect on some things and some people?  Who knows?

Gizz, thanks for doing more research on this phenomenon.
 

Tinhorn

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Good Job on the research Gizz,

and Thanx for the timing info.  

Thats a good idear (Oops, that's a typo, I'm not from Maine) to cure the slower camera's "Flash Recharge" problem.  That's a super idea actually...

Good Thinking

Tinhorn
 

gtk

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Thnx Gizz... So, If I go into Radio Shack and ask for a 100k resistor, they will give me what I need ?  Is the r26 resistor marked on the ms20 where it's noticable ?

Thanks again... This sounds like just what I need.
 

gizz

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Yes gtk, Radio Shack will have what you need. I bought an Assortment of 5% tolerance(no idea what that means) resistors for a few dollars. If you do this you can play around with different values to see what you can get out of it. R26 and R25 are marked on the MS20, as i said earlier one is 2.2M resistor and the other is 33K (the "test" one).

This is the "lazy" person's way of dealing with the lazy owl pf flash. The best way of course would be to build the refresh pulse but i'm lazy. Did I say Lazy?
 

Jaggermax

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For my last set of cams, I designed an integral RE200B PIR circuit onto my microcontroller board based on the circuit from Glolab.  

I think the RE200B is the same PIR sensor used in the MS20 detector.  I made three boards, all with identical components.  One board has the normal 20-30 warmup period (from a cold startup).  Another board has about a 60 second start up delay.  The last board has only a 10-20 second delay.  I decided to wire up the same detection circuit on a breadboard minus my microcontroller components.  I plugged in four different RE200B pir sensors (purchased from mpja.com) into the circuit and they all had varying delays from 20-50 seconds.  I think we are just seeing some variance on the electrical characteristics of the sensor itself.  I guess this is just normal between different manufactuing lots for this sensor.  The RE200B is one of the cheaper all purpose sensors out there so this may be why we are seeing the deviation.  
 

Tinhorn

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Thanx for the report Jaggermax

Once I played around with an MS20 and checked out various things, one of which was the power up delay.  I don't remember anything about what I found except I remember I couldn't do anything about it (huh?)  ha ha

and I bet what you found is why......

Tinhorn
 

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