Thanks to all for your help. Indeed the schematic is
on the cardboard. I've made a LTspice model of it and
am trying to understand but I'm just a software guy
trying to learn. I've had an offer for the datasheet
and followed up on that.
BTW, I bought the 150-1 a couple years ago at a flea
market for maybe $5. Box is quite worn but inside it
had never been used and now that I've got some time
I've dived into it.
Jim