Transformer I have used is a | Electronics › Electronics › Auto Cut Off Battery Charger with LM317 & BD139 › Transformer I have used is a March 14, 2013 at 2:25 am #9316 IrfanParticipant Transformer I have used is a 18-0-18 1.5Amp Battery is 12v 7.2 Ah wysiwyg_imageupload:7773: