I had an old one that finally gave up the ghost. I shopped around and found I could buy this fairly cheaply from Zareba.
http://www.zarebasystems.com/zareba-15-mile-ac-solid-state-charger-a15
I had it for a couple of years keeping my pit bull from tearing down the wooden fence. He would literally rip the 1x4 dog eared pickets off the fence, break them in half, chew them in half. Used it with regular 17 ga aluminum or galvanized wire, the light weight stuff.
Last year, I moved a garden that I had at a business location, further towards the back of the property and the hogs started moving in. I took the fencer from the house and moved it out there. Bought a roll of polywire and it works fine.
http://www.gopjn.com/t/2-215656-43737-137077?sid=j0sdfazpje00zk8a02lk7&url=http%3A%2F%2Fwww.tractorsupply.com%2Ftsc%2Fproduct%2Famerican-farmworks-poly-wire-1320-ft
I either use t-posts with a donut insulator or I spent $2 on the little insulated pickets. I've got several "gates" where I can take it down and mow. The whole place is only 7 acres, and the charger seems to do alright for the little bit we have fenced. I'm working right now on extending.
Less than a week after I moved the charger, my pit bull figured out the wire was dead and he tore out about an 8ft section of fence and just would run around playing with whatever neighborhood kids he could find. He's just a big dopey dog, but I figured someone might shoot him. I was tired of replacing boards, so I went out and bought welded cattle panels and put them up against the fence.
http://www.gopjn.com/t/2-215656-43737-137077?sid=j0sdfb0gwe00zk8a02lk7&url=http%3A%2F%2Fwww.tractorsupply.com%2Ftsc%2Fproduct%2Ffeedlot-panel-cattle-16-ft-l-x-50-in-h
He then figured out he could stick his head through this, rip at the fence, then pick up the panels (that we were wired together), crawl under and escape.
So then the t-posts were put in and the whole thing was tied down and electric fence wire was rerun.
I shopped around for something more backyard appropriate and ended up with this.
https://www.amazon.com/dp/B00536X0AS?tag=vglnk-c102-20
Cheap, but effective. He finally gave up tearing down the fence. This one is continuous low voltage, while the other ones pulse. I swear they can hear the pulse and know when it's unplugged.