Re: Optical paper tape readers I have a number of PTR's from industrial controllers (my field). Smallish Facit units (about 2.5"h x 4"w x 3.5" deep) - late 70's / early 80's model ? Mod 4032 (have circuits diagrams and an interface unit for this, and also a diagram I made to interface to bi-directional PC printer port.) I also have one or two older Remex units that's a little bit bigger (about 5" x 4"), quite robust - mid / late 70's model. These mounted on a 19"rackmount plate with power supply (240V input) and a pulse generator to simulate step pulses (though this can be bypassed). and some very modern looking (mid 80's) units from Data Specialties Model R150. These are really cute little units, only about 2.5" all round and weigh nothing. They have a led light source too, so no filament burnout. These have an external interface board about 3" square to link to TTL level and I have pinouts for this. All units are designed for panel mounting, but you could easily mount them in a small metal or plastic case for bench use. I want to keep some of these, but if you're interested, contact me and we'll see what we can work out. I'm in 'down under' by the way. BTW, not sure if anybody has seen the waaaay old Siemens PTR's that didn't use light. Instead they used small wire brushes and contacts underneath - ah the old days! ;o) Grant