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Build your own remotely operated MP3 game caller!


This is reprinted with permission from the author, Arkansas Elk Hunter.  He got the plans for building it from Predator Masters and then wrote up his instructions, which you will find below.  Make sure you take all manufacture recommended safety precautions when working with electronic equipment!

You can find the Arkansas Elk Hunter's website at here at his website.  Good luck with the build and if you have any photo's of your build or suggestions to make the process easier just contact the webmaster to get it added to this page.


Homemade MP3 Game Caller

First let me say thanks to The guys at Predator Masters for their innovation on this project. I copied this design from their forum members. Pay them a visit, you'll learn a lot. Here is another Tutorial written on the subject with some great information.


It Works Great!

This is my Electronics Caller.

I'm getting a good 100 yds with pretty good sound quality. I also added a rigid antenna from Radio Shack to the nady receiver that helped a lot. Use a 4' to 6' patch cord between the transmitter and MP3 Player for better range. The cord also serves as the antenna. I have about $150 in the complete unit. You can transfer your sounds from tape , CD or download some good sounds from Western Rivers



The heart of this caller is the Nady 351 wireless microphone system. Several versions area available. The 351 is a little smaller but costs more than a similar unit Nady 151. I bought mine new off E-bay for $72.

You can buy the Nady 151VR new here for $73.95



A unit by Azden is also available and can be purchased here for $134.95. Go to the predator masters forum for a discussion comparing the two brands.

The Caller is housed is a Energizer Outfitter Flashlight Housing. The light comes with two little saddle bags on each side. Walmart carried them and closed them all out in January. You can order one from Batteries.Com for $15.99 plus $3.99 shipping. There are many other options for a housing, but this is one of the slickest I've seen. The MP3 Player and transmitter fits in one side and the receive fits in the other.

I used a 15 watt horn from the Phantom Predator Call just because I a friend could get me one at cost and they were green. I paid $20 but you can get the same horn in white for $8 here. It's the SPECO SPC-5


The lens needs to be removed and cut out for the Horn Speaker. First remove the clear polycarbonate lens from the black bezel. Next the Reflector needs to be removed from the clear polycarbonate lens assemble by popping loose the glue joint. Then cut the entire polished lens out of the polycarb lens. Watch the threads and be careful not to damage them. There is a nice little step on the inside you can follow all the way around. You want the speaker to fit completely up against the black bezel..


Next you need a heat gun to widen the mouth of the flashlight a little and allow the speaker to slide all the way in to the bezel. (See the red circle in the figure to the right) With the bezel removed, heat up the housing with a heat gun until it's a little soft and shove the speaker down into the housing. Allow it too cool with the speaker in place. Be careful not to melt the switch or warp the threads.

There are some ribs on the inside of the housing that guide the D-cell batteries in place. Remove them with a wood chisel to give more interior space if you like.




After fitting the housing as shown above, you need to glue the horn in place. You will need to cut off the mounting brace from the horn so it will not hang up as the horn and bezel are screwed onto the housing. Grind it flush with the rest of the horn. There is a little extra material on the switch that can also be removed to make a little more room. You don't want any undue wear on the speaker wires as it is assembled.

Position the speaker in the center of the bezel assembly and put just enough hot glue on it to hold it in place. Test the centering by screwing the bezel onto the housing. Adjust the horn position so that you feel no resistance and it is rotated. Then remove it and add more hot glue. Glue it from the inside and just fill up the groove between the speaker and the bezel.

I wired into the existing switch to provide power for the auxiliary amplifier and the Nady receiver. The switch can be removed with 2 screws. I also added a LED to the circuit so I can see if the switch is on or off. (See figure to the left).

I wired in a 9 volt battery clip that snaps onto an 8 cell AA battery holder. I can add 8 NiMH batteries to get 9.6 volts (8 x 1.2 volts = 9.6 volts) or add 6 Alkaline Batteries for 9 Volts (6 x 1.5 volts = 9 volts) by using two fake batteries made from aluminum Rod in place of 2 cells.

I used a hobby shop Servo Connector for the auxiliary battery supply for the receiver. I opened the receiver. and soldered the servo connector wires to the existing 9 volt battery leads of the receiver.



Drill a small hole in the end of the flashlight housing just large enough to get the battery connector and speaker plug through. Cut a small hole inside one of the pockets to run the wires into the saddle bag that the receiver will fit into and you will never see the wires when the bags are in place.

The Diagram on the left shows how I wired into the existing flashlight switch and use a LED to indicate on/off status. 




Thumbnail .... click to enlarge.



How to add a telescoping antena to tha Nady 151VR LT



I also added a small radio shack Amplifier to the unit. I took the board out of the Original housing and added it to a 4 AA battery holder. I used a dremel to remove all the internal features of the battery holder and the board fits perfectly. Use the dremel to cut a slot for the Volume knob and the input and output jacks and your done.

Originally I was getting a little feedback when using a single power source to power both the amp and the receiver. I added a Isolation Transformer and the problem went away. It is the little green square in the middle of the Amp.






The last piece of the puzzle is the Player. Any media player can be used: Cassette tape, CD, MP3. I selected a Rio Sonic Blue 128meg player. The Rio is compact but large enough to handle with gloves. It also has an easy user interface and lighted display and displays song titles for easy selection in the field.

Any MP3 player will work, so make your best deal. E-Bay is the way to go there. Just watch the "buy it now" selections.


Just let me say once more, I just copied this design from the guys at Predator Masters. Give Credit where Credit's due. Thanks Guys

I hope this might help someone else out a little.



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