In search of 20ma to eia converter

I have an old serial paper tape reader which runs with 20ma and would like to use it to archive all my pdp-11 (and some pdp-8) paper tapes. But I need a converter... Can anyone help? Any pointers to a simple schematic? Megan Gentry Former RT-11 Developer +--------------------------------+-------------------------------------+ | Megan Gentry, EMT/B, PP-ASEL | Internet (work): gentry!zk3.dec.com | | Unix Support Engineering Group | (home): mbg!world.std.com | | Compaq Computer Corporation | addresses need '@' in place of '!' | | 110 Spitbrook Rd. ZK03-2/T43 | URL: http://world.std.com/~mbg/ | | Nashua, NH 03062 | "pdp-11 programmer - some assembler | | (603) 884 1055 | required." - mbg KB1FCA | +--------------------------------+-------------------------------------+