OT: Need circuit assitance for deer feeder

Shake1

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 I recently purchased three deer feeders from a guy leaving our deer lease.  They all had mechanical timers in them and I want to swap them out for digital timers.  I got an idea about building some inexpesive digital timers.

 I recently found a potential timer at RS, purchased it and then diassembled it.  It was meant to provide programmable features for a 110 outlet.  I would like to try and use this circuit but I need assistance with designing a circuit to control the feeder timing and motor.  By the way - the timer was $20, Radio Shack PN #61-1065.  The programmer portion within the unit is very small and runs off a 1.5v AA battery.

 What I've got so far:  I isolated the programmer portion from the 110v relay portion of the unit (used to power appliances, lights, etc.).  The output of the programmer is held at 1.5 volts for the duration of the scheduled event (on state).  The least amount of time I can program an event to be on is one minute.  When the event is over, the output returns 0v (off state).  I would like to try and use this programmable circuit as a switch to turn on a timer to control the feeder motor.  The feeder motors I use are both 6v and 12v.

 The part I need help with is the timer circuit and the portion provides juice to the motors.  Would be nice to also be able to provide the 1.5v back to the programmer as well (but not neccessary unless they need to share a common ground).

 I was thinking I could apply the programmer's 1.5v output to the base of a transitor to power up a timer circuit, controlling a relay tied to the motor.  One "gotcha" - the shortest duration outputted from the programmer is one minute at 1.5v (on state).  Therefore the timer must not reset until after the voltage goes back to zero (off state),

 As I'm rusty in my electronics design knowledge (EE training 13 years ago) I wanted to ask you guys for assistance on this.  If you can help me get a circuit designed and working I will document it and submit it to the forum for others to build.  Seems pretty easy and straight forward.  Beats paying $75 for digital timer to use on a deer feeder.

Thanks all,
Shake1
 



Brian

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I have a design that I have been using now for about 6 years that seems to work great.  I have also recently programmed a micro chip to do the same thing.

I will try and get the schematics together today for and post them on my site.

The circuit takes the 1.5 volt trigger(needs its own battery so you don't have to set the clock eveytime you change the feeder battery) and triggers a one shot (settable by a POT for the duration of the feed time) which is only triggered off the rising(or falling) edge of the 1.5 volt trigger.  So it doesn't matter that it stays on for a minute.  If you use falling edge then say you wanted to to go off at 7:00 AM you would set the timer for 6:59 AM and it would trigger when it changed to 7:00AM and just the opposite for a rising edge trigger. The alarm timer would be set at 7:00 AM for rising.

I will try to draw this up today and post it.  It is very simple and cheap to build and works like a charm.  I have had six years of testing it in West Texas with little or no problems.  I use a socket for the chip so it is easy to replace if it does go bad.

If I am not mistaken I think I have used that timer before and it works in this application very well.



Here is a link to the schematic.
http://briang.netfirms.com/page19.html

(Edited by Brian at 10:49 am on Mar. 29, 2002)
 

Shake1

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 Thanks Brian!  I will use the positive edge trigger.  Couple of questions on the circuit you provided:

 Are all resistors 1/4 watt?

 What kind of transistor is closest to the timer w/alarm?

 Is the 10uf capacitor providing timing polarized?  If yes, which way?

 In regards to "all grounds have to be connected" - do I also need to tie the ground of the 1.5v battery source (for timer w/alarm), to the ground of the 6/12v battery as well?

 If all goes well, I will purchase two more units and build them.  While doing so I will photograph what steps I take from start to finish and provide a schematic for everyone.  How has this timer unit been working for you in the field?

Thanks again!
Shake1
 

Shake1

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Thought of one more thing - can you configure a diode in the circuit to prevent destroying the circuit should someone accidentally reverse the 6/12v battery?
 

Brian

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Shake1,

All resistors are 1/4 watt.

I thought I labeled the transistors but the one closest to the alarm is a 2N3904.  I missed labeling it Sorry.

I just threw this together from memory so I did leave a couple things off as you noticed.

The capacitor can be polarize and if so the negative goes towards the gate on the positive edge and away from the gate on the negative edge.  Keep in mind the RC combination can be changed to suit your timing needs but it has physical limits so start with the values you see and work from there.

Yes on all the grounds or the circuit cannot see the 1.5 volt signal.  They have to reference each other.

I have had them in West Texas now for about six years with minimal problems.  Usually, hogs or somthing destroys them but they are still ticking.

On the diodes. YES
You will need a blocking diode for the motor too (I forgot it) and yes a diode on the electronics would be nice but do not use it on the VCC to the TIP120 because this will need the raw battery voltage or you would need a diode that could handle 4Amps or more.

BTW, The cost of these parts from Jameco comes to a little over $2.00.  Not counting shipping of the parts to you and I could have the two backwards as far as Positive and Negative edge triggered.  This is all from memory.

I will email you the spec sheet on the CD4093 chip too.
 

Shake1

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Thought I would put a 1N4001 in series with line providing power to circuit.   For feeder motor I will bypass the diode and wire directly to power source.
 

Shake1

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 Any of you ever added a remote control feature to your feeders?  Where I hunt (N. Central Texas), there are lots of hogs and it is not uncommmon for them to run in to a feeder after it has gone off.  Once they're finished eating everything, they scamper off.  Whenever this has happened, I've had to climb down from my blind and set the feeder off manually.  The deer usually come back in afterwards.  Would be nice to do this via remote control instead.

Shake1
 

Brian

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Shake1,

Yes I have used it but the receiver that has to go in the feeder draws to much current to make it practical or at least mine does.  I have been working on reducing this current draw.  Just haven't got back on that project yet.

I think the idle current was 8mA.

You can look at these locations for RF links if you want to try and build one yourself.  Keep in mind the current drain will kill your batteries if not power efficeint.

http://www.glolab.com
http://www.rentron.com
 

Brian

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I would steer away from the top design.

The bottom link TX/RX pair is good.  They can be found on http://www.rentron.com as well.

The manufacter is http://www.laipac.com.  You can get circuits for design from them or rentron.  These work well.  Keep in mind the ground plane needs and the antenna for best performance.

They are on my list for my next project.  They are more power efficeint than the ones I am using now. http://www.linx.com
 

Shake1

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Cool.  The http://www.linx.com/ link brought up a marketing company's website.  Please repost the inteneded site.

 Are you familiar with a search engine called Global Sources?  You can use it to source just about anything made in the world.  Often, they will send samples to you.

http://www.globalsources.com/
 

Archilochus

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Hi guys,
Check http://www.abacom-tech.com for low power RF stuff.

Rx @ ~ .4mA (at least for the sample I got a couple years back).

Ground planes & ant. required for their parts also to get max range.

Archilochus
 

Shake1

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Thanks Arch.  Have you done anything like this before?

Shake1
 

Archilochus

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Hi shake,
I didn't use the RF parts for a feeder - used them on a trail-cam where the sensor was mounted remotely from the cam itself (similar to what Brian did).
The basic idea is the same though.  You just need a low power RF reciever on the feeder so you don't kill the batts fast.  That's where the Abacom parts come in handy with their relatively low power consumption.
I'll try to root up the part # for the recievers I used and post them.

You might also consider IR remote control if you have a clear line of sight.  Or maybe even hard-wired would work.

Archilochus
 

Shake1

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 In my situation, power drain is not as big of a concern.  Also, all of my feeders have solar panels on them.

Shake1
 

Archilochus

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Since power consumption is not a major problem, you'll have a wide variety of RF Tx/Rx modules to choose from.

You'll probable want to use some basic encoding to keep the feeder from getting triggered by RF noise and other spurious signals.

See this (unfinished) page for a bunch of links to RF stuff:
http://www.geocities.com/archilochus57/rf_tx.html

Archilochus
 

Brian

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Shake1,

Even with Solar Panels you should try to keep the current down.

A 50ma Solar Panel only gives this much current during full sun and an 8mA drain all the time would eventually overtake the Solar Panels ability to recharge the battery.

Been there done that.  So try to keep it down if you can.

I have been using Pulse width modulation with the sleep mode of mine to get a 50 % duty cycle so I can reduce my current in the Linx module from 8 mA to about 1ma.  Significant but not great.  The other modules seem to be better but with the PIC they give noise when not receiving and require support chips to stop this is the only reason I haven't used them yet but I will eventually.
 


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