Ian, Why can't you just reverse the inputs? There's only one current input so you can't reverse it. You may be thinking of the LM13700 or CA3080 which has an op-amp front end. Neil -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://synth-diy.org/pipermail/synth-diy/attachments/20170826/a9219ca0/attachment.htm>