RS 49-425 Sensor

Richard Webb

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Arch-

I keep thinking about something easy to solder together, like a simple timer using a capacitor parallel with resistor. The capacitor would quickly charge from the output of the 49-425, and then slowly discharge through the resistor.  (Preferably, the resistance of a phototransistor.)  But, in any case, the charge would keep a transistor turned on or off until it's desirable to turn the PIR sensor back on.  Am I on the right track?  Those timer circuits just seem a little too advanced for the average hunter to breadboard.
 



Archilochus

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Hi Richard,
That idea sounds like something I remember from many years back.  I think I might even have a copy of the schematic hiding out somewhere.  If I can find it I'll send you a copy. If I'm remeberin' right, that type of circuit is why the 555 was invented.  You need a 'signal level' transistor, two or three resistors, a capacitor, and probably a second 'power' transistor to buffer the first one. And the timing was always tricky to get right. 555's or 4538's starts to look easy after all that.

Archilochus
 

Richard Webb

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Arch-

To be honest, I'm having a hard time explaining your IC Chips to my 11 year old boy, and he's my partner.  I finally got that kid away from his mother!  Yes, my electronic ideas are from the days of steel chaises, electron tubes, and paper capacitors.  I remember when a 741 OpAmp was high tech.  The extra resistors you mentioned were usually only voltage splitters.  A simple resistor in parallel with a capacitor that will put 0.8 volts at the base of a transistor will only stop putting 0.8 volts at the base after the capacitor discharges.  There is a math formula for the values, and it probably got lost during the computer age when clock speed and timers became more precise.  I appreciate your patience.    
 

Tinhorn

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Here are a couple Delay At Startup Circuits I found in my Notes.  Apparently, I breadboarded these at one time because I had a note saying "Not Energy effiecent" by them.  The transistors were not ID'd nor were there any delay times listed  but I doubt if the transistors were critical, and guess they are NPN's



Tinhorn
 
K

KMILLER

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I've been pleased with the performance of the RS in my cam. I've caught deer at 50 feet @ dusk, a trotting red fox at 30 feet @ 3pm, and a rabbit at 10 feet @ night. The fox made it just past half frame before the shutter closed. The front half of the RS housing is JB Welded to an ammo can, maintaining the alignments.
 

Richard Webb

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KMILLER-

Yes, I had problems getting the Fresnal lens aligned through the small Radio Shack plastic box.  It would probably work a lot better with the whole unit mounted.  Luckily, I didn't cut or glue the lens, so I still can go back, reassemble it, and mount it like you did.

Tinhorn-

Thanks for the drawing, and we will experiment with the one transistor timer this weekend after I go get the cam out of the woods.  

 
 

Richard Webb

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Hi Arch-

Is it okay to use a large sheet of glass inside the box, and let the 49-425 PIR Fresnal lens look out through the glass?  I'm thinking about putting one of Jon's Cams inside a 7.62 ammo box, but there is room in there for two of those large Lantern Batteries which makes using the MS20 an option.  Just received two more Owl PF's from Amazon, and it only took 3 days total time from order to receiving.
 

NC Bowhunter

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Hi guys,
I've just started working on my second trail camera, both using the RS 49-425 sensor.  A few days ago, I tested it out in my house, and it picked up my movement from 50 feet away which is as far away as I could go.  Also, in my first camera I have been pleased with it's preformance.

I mounted this one inside the front half of the housing it came in, with the fresnel lens glued to the enclosure box.  This has achieved the best results for me.

Now, I think I am going to try one of these timers and hopefully have some adjustable time delay.  With all of this information, I might be able to get a timer working.
 

Archilochus

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Hi Richard,
PIR sensors can't "see" trough glass, most plexiglass, and many other types of plastic.  On my home-made PIR sensors I use some very thin plastic sheet for "blinders" to narrow the field of view.  Even though the stuff is very thin it still blocks the IR from reaching the sensor.  You can buy specialty plastics for making PIR 'windows' from http://www.fresneltech.com or you can just experiment with various plastics until you find one that works.  Use very thin material so you don't lose too much of the signal.  I use extra plastic layers to lessen sensitivity in certain situations on my sensors that have non-adjustable sensitvity.
>>>>>>>>>>
I'm pleased to hear that others are having good results with their 49-425s.   I hope mine works as well!

Archilochus
 

Richard Webb

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Archy & Tinhorn,

Resistor R14 is in kind of a bad spot to un-solder & lift out one side, so how about cutting the foil on the Pin 2 side on the back side of the board.  Then, running a jumper over to pint 4 of the small IC?  Thought I had better check with you guys first.
 

Tinhorn

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RB

Your idea looks ok to me (pin 2 of the small IC will end up not being connected to anything, right?)

I don't have the RS PIR to look at but was going by the Schematic.  I hope this works out and the modification is not too difficult for others to follow....

Try to make sure you can "Undo" the mod, just in case   :)

Tinhorn

(BTW, can you tell what R14's value is?  I can't read the value on the schematic)
 

Richard Webb

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Tinhorn-

What amazes me is how tiny they make things now-a-days.  Resistor R14 is marked Gold, (no stripe), and Red.  Forgot how to apply the "Bad Boys" formula, but hope that violet is putting .8 volts on the base of that transistor?  One side of R14 goes to the transistor, and the other directly to pin 2 of the small IC.  Pin 4 of the small IC goes directly to Pins 2 & 20 of the large IC.  Should I cut the foil, and run a jumper to pin 4 of the small IC.  It looks like when Q1 switches it will output the battery voltage, which means I had better find a 9 volt relay.  
 

Tinhorn

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RW

Yes, you are right, Cut the Trace so Pin 2 goes nowhere and Jumper Pin 4 to the cut trace (that goes to R14.

You are also right about watching the volts on the Base of the transistor but I think it will be ok.  The voltage swing of the Audio was probably "Rail to Rail" {Batt (+) to Batt(-) }

You are also right about the relay coil needing to match the Battery Voltage.

Don't you get tired of being "Right" all the time ! ! !   ;)

Tinhorn
 

Richard Webb

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Hi Tinhorn,

With $75 invested in these 49-425 Sensors I'm moving ahead very carefully double checking everything.  If your modification works by simply cutting the foil in one spot and soldering a single jumper, then I think Jesse should add your idea to his WegPages.
 

Richard Webb

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Tinhorn-

The voltage at the base of the transistor jumped up from 2 volts to 4 volts when I cut R14, and jumped to pin 4 of the small IC (with a plain wire).  Will that transistor stand up to 4 volts on the base, or should I use another resistor as a jumper?  What resistance value should I buy if a resistor jumper is needed to bring down the voltage?
 

Tinhorn

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RW

When did you get the 2 volts on the base, out of curiosity?  Before you made any mod's I guess.

I am guessing you need to replace the jumper with an 8 to 10K so why not get a variable about 50K and use it for now.  Adjust the variable to max resistance and replace the jumper with it.  Connect your relay coil to the speaker wires and connect your "Ohms" meter across the relay contacts.

Energize the PIR, hopefully, the Ohms Meter "Won't" deflect yet.  (If it does, then the Resistor may need to be bigger)  If it don't then while waving your hand, slowly decrease the variable until the relay closes and the meter deflects.

Then you could remove the variable and measure it's resistance and use a FIXED resistor.  I think I'd want it to be a little less resistance just to be sure the relay is pulled in real good.

Hopefully, the variable won't be adjusted too close to one end or the other and it will be more "Centered" for a more reliable measurement.  

I and others are really glad you are taking the time to experiment with this thing.  I can tell you have a pretty good understanding with what needs to be done and it will be a great help.

Thanx a lot

Tinhorn
 

Archilochus

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Hi Richard,
Maybe I'm got something wrong here.....but aren't you supposed to jumper the resistor to pin #2 of the big IC??  So that pin #2's output will drive the base of the transistor.

Archilochus
 

Richard Webb

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Arch,

Pin 2 of the large IC is directly connected to Pin 4 of the small IC, so I picked the closest one.

Tinhorn,

I found an old 50K Potentiometer out in the garage, and it gave me a 40K Ohm reading.  Went to Radio Shack, and purchased some 47K & 33K resistors.  The 33K brings the voltage down to 1.5 Volt, and the 47K brings it down to 1 volt.  All measurements are from ground to the input of R14 (without) unsoldering the resistor or transistor.  I figure if R14 was seeing 2 volts that way before, then we should present 2 volts that way again.  But of course, we really don't know what is going on inside those IC chips, and I don't have a scope.  Radio Shack didn't have a 9 volt relay, so I had to give up for.  The 49-425s work good with a 5 volt relay on pin 2 of the large IC, and the walk light on the speaker wires.  So, that's the way I'll setup the trail cams for the summer. If there is anything left of the 3 cams next fall I, will tear them down again, and do it right.  It was probably beginners luck, but the first roll of pictures came out pretty good.
 

Archilochus

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Hi Richard,
I checked the various outputs of the 49-425 on my old 'scope.  Here's the results:

Pin #2 of the big IC - 0V at idle -  ~ +4.8V when motion is detected.

Pin #2 of the small IC (measured at the IC pin) open circuit at idle - And a varying waveform that goes from 1kHz @ +4.8V and tapering off to 750Hz @ +2V when motion is detected (chime mode).

So the speaker transistor should handle the the full output voltage of pin #2 of the big IC no problem without any additional resistors added.  I'm guessing the meter you made your measurements with could not deal with the audio frequency signal from the small IC and just averaged the signal to 2 volts.

To answer an earlier question... The resistor "R14" on my board is a 470,000 ohm, 5% resistor.

>>>>>>>>
A good way to aquire a free used scope.... Go to the research departments of any college and ask them what they do with "obsolete" equipment.  Often they just throw it away!!  That's how I got my 'scope.  I left my name and asked them to call if they ever planned to chuck any old equipment.  It's an older 'scope but is more than enough for the hobbyist.

Archilochus
 

Richard Webb

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Hi Arch,

Thanks for posting the valuable Scope data, because it will be helpful to me and others while working with the 49-425 board.  When I was active in ham radio I had a two car garage full of test equipment, but after the first wife went home to be with the Lord, the second wife talked me into taking all that stuff to the dump. (a complete communications station with teletypes)  But of course, it was tube type equipment, and when I turned it on the heat from the tubes would heat up the dust & cob webs inside, and give off a bad odor.  I visited your WebPages, and like the improvements you made.  Getting back to the R14 modification, Radio Shack didn't have a 9 Volt Relay, so I used a 12 Volt Reed.  It worked good for a while with wire jumper, but was being activated something other than motion.  Then, after a while the 12 V relay stopped working. Also, I noticed that Pin 2 of the large IC was switching on & off in succession for no reason.  I forgot to use a diode on the relay during the test, so is that probably is the reason.  Any ideas?  
 


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