The previously mentioned Varmint Al webpage has plans for an electronic caller and excellent audio files which can be downloaded for free. Here my $10 caller solution. I downloaded the audio files from Varmint Al. Then I purchased a yard sale "boom box" which had both a CD player and cassette tape deck and will work on internal batteries. Problem solved, perhaps an external speaker would be louder, but they do not call them "boom" boxes for nothing. I hope this helps.