Camtrakker AGC Option??

spectr17

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Here's a thread on the Bowsite about  game cameras and heat. About half way down GarKing talks about the AGC option on a Camtrakker turning the unit off in high temps. We own a 1994 and 2000 model Camtrakker and I've never heard of this feature or option. Anyone else know anything? My Dad has the cameras so  I can't get the op manual out to look and I dang sure ain't calling their customer service. I went through that root canal last year.

http://www.bowsite.com/BOWSITE/TF/thread.c...=34&forum=4

AGC has more to do with amplifiers. AGC = automatic gain control. I'm thinking they are boosting or limiting the detection amp of the PIR sensor and not the temperature.
 

Brian

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When I build my sensor I put a POT in place so I can adjust the sensor during the summer to reduce the false triggers.  If you can back the detection up to around 10 steps the camera seems to work better.

A PIR sensor uses gain to amplifiy the signal to where the trigger level is set. By adjusting the amplitude of the signal you can modify the sensing distance.  I have tested all this on a Scope Meter and it is amazing how the signal responsed to everything.  Most of the sensors I have delt with have a voltage divider set up for the trigger that is usually half the supply voltage and then adjust the sensitivity by adjusting the gain.

Most likely the AGC uses a temparture sensor inconjuction with and adjustable resistance.  If the temp gets to high or to a certain point then the electronics would automatically adjust the resistance.  They have what is called a digital pot that can be controlled incrementally with the rise in temperature.  I have built such a circuit but I have found it more econimical and more efficeint just to use a pot that can be adjusted manually in summer and winter.  There is kind of a sweat spot that  I have found that works in both summer and winter.  I still may get a few false triggers but not many.

Brian
 

KsBowhunter

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Brian,
Let's see a circuit diagram for this POT if you don't mind. Sounds very interesting.
 

Archilochus

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Hi Brian,
I agree on the manual adjustment.  Automatic temp compensation is OK if you're only trying to get a certain size animal, but for maximum flexibility nothing compares to manual sensitivity adjustment. I have my sensors designed so that they can be adjusted from rediculously sensitive down to close-up only detection. A simple pot to control either gain or set the trigger threshold is very easily implemented.

I used some passive Trail Masters in the past (they have AGC circuitry) and found it irritating to not be able to select sensitivity levels manually.

Archilochus
 

Brian

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Hello Arch,

Archilochus has a great schematic with just this option on it.  You can find it at his website.  

http://www.geocities.com/archilochus57/images/sensch.gif

Notice the pot in the first stage of the Quad Op Amp.  This adjusts the gain for the next stage and allows an individual the flexibility to modify the trigger distance.

He has a really great site with lots of goodies on it.

Arch,

I don't know if you know this or not but you can replace your chip with two independant chips and put your current draw down to 20 uA idle.  I don't know what your circuit draws idle but I just thought you might be interested.  The first stage of your circuit would be replaced by a MAX407cpa.  This is a dual micro power OP AMP. and the last piece would be replaced with a MAX922cpa which is a dual micro power comparator.  Your overall design would have to change slightly but essentially would be the same.  The reason for the design change would be because the chips are already specialize for being a comparator and do not need to be configured into one like the op amp has.

Brian


PS. There is also a great low power day/night sensor at this address:http://dbserv.maxim-ic.com/appnotes.cfm?appnote_number=237

The circuit draws 4 to 5 uA at max and 2 to 3 uA at min.





(Edited by Brian at 1:40 pm on Aug. 17, 2001)
 

KsBowhunter

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The page wasn't available or wouldn't open for me.
Can these POTS be used w/the MS20 board or do you have to build your own PIR?
 

Brian

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I have never used a MS20 board so I couldn't answer that.  I have always built my own.  My guess would be that you should be able to modify it but that is really going out on a limb since I have never taken one apart or used one.

I may have messed up the link when I copied it.  Go to Jesse's home page and click on Camtrakker.  Then go to Home brew camera section.  At the end of the page is a link to Archs page.  Along with other useful links.  That might fix the problem.

I don't have time this year but maybe next year I plan on having some of these boards etched to sell if anyone shows any interest between now and then.

I am working on giving this web page a digital camera interface board but I am waiting on a friend to send me a generic sensor that ya'll use so I can modify the circuit for use with it.

Brian
 

Archilochus

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Hi Brian,
I actually have two sensors built with the exact Maxim part #s you mentioned. I love Maxims' parts! They always work as specified and never give you any unexpected "suprises". I ordered the parts as samples from Maxim.  When I went to buy a bunch from Digi-key, I almost fell off my chair! The 'commercial' 407 sells for almost 7US$ !! - the 922 is a bit better at 3.50US$
So that's why I switched to (and used them in the schematics) the ST parts - At 10uA per op-amp the power consumption is reasonable and the price is only 1.12US$ for 'industrial' temp range parts.  Performance is fair - but you don't really need a great op-amp for PIR signal amplification anyway.  I tried to use STs' micropower comparators for my "window comparator" but they would oscillate for several seconds  every time the output switched - couldn't fix it no matter what I tried.
>>>>>

Just wondering if you know of any low-volume or retail sources for Heimann (Perkin-Elmer) PIR sensor elements??  Can't find the things for sale anywhere!!  They are the best I've found so far, but the only way I have ever laid my hands on any is to get samples all the way from Germany!!

KsBow... try looking at the index page
< http://www.geocities.com/archilochus57 >
Then select the "Basic sensor" link.

Archilochus
 

Brian

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Archilochus,

I don't know where  to find the Heimann sensors.  I tried some time back but the only place that I found them was on a website in England.  They were about 5 bucks a piece so I stuck with the RE200B sensors and they work really well.  I haven't had any trouble out of any of mine.  I got a quote from NICERA for the RE200B sensor at a dollar a piece but you had to buy quantities of 1000.  Needless to say I didn't do it.

You might check into the micro power op amp from Holtec.  The HT9274.  It is a pin for pin replacement for the LM324.

I helped some guys who where building some sensors with OPAMPs once and I found that if you use a filter method at the trigger output the Comparator could oscillate at the end before resetting and it would not false trigger your circuit.  I used a 1uF cap with a 1M resistor.  If your signal has small oscillations less than a second then this will work.  
If you are not famaliar with this type of filtering method let me know and I can draw it out and email it to you.  If fixed even the worse oscillations on the LM324.  Or if you can give me the part number for the ST chips I can try it later when I get a chance.

You can buy the Maxim parts directly from them cheaper than from Digi-Key.  I do it all the time.  I believe I paid just over two dollars for the 922 last time.  They come from the Phillipines.

If I every run across the Heimann i will let you know.

Did you get a chance to check out the micro power day/light dark circuit.

Brian
 

Archilochus

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Hi Brian,
Sure, I'd love to see your method for solving the oscillation problem. The STMicroelectronics part# for the comparator I had problems with is TS3702ID

Any more details on how to get the Maxim parts??

I checked out Maxims' circuit - very nice!  Sort of a refined version of the crude day/night sensor on my web-site.

Archilochus
 

Brian

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Arch,

I will check into the oscillation problem and see if I can help.

The maxim parts can be ordered through their web site.  You will have to set a login and a password and then you can get quotes.  I have found that it works better if you call them directly and order that way.408-222-7230  Be patient they will leave you on the phone forever but eventually they will pick up.

Brian

PS.  I am assuming you used the TS27L2ID and the TS3702ID for your OP AMP and Comparator circuit.

(Edited by Brian at 1:31 pm on Aug. 20, 2001)
 

Archilochus

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Hi Brian,
Yup, that's the combination of parts I tried when I had the oscillation problems.  For now I'm using the quad TS27L4AID and just using the last two op-amps as the "window comparator"

Archilochus
 

Brian

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I ordered the parts yesterday.  I will see if I can fix the problem.  I'll let you know.

Brian
 

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