Else you'll need to replace the DM7400N with someething stronger;
the DM7400N chip can only produce 0.4 ma so it's not going to work,
A SN74AHC00N chip can procude 8mA on the outputs which is probably
close enough to 20mA for it to work, replace the 1K resistors with
wire links.


Thanks for your help. My power transformer only had a rating of 1 Amp, so I
picked up another one today with a rating of 4 Amps. While at the
electronics store, I also picked up a couple of the SN74AHC00N chips you
mentioned. Is the logic the same as for the DM7400N?

As soon as I get the new transformer mounted and wired in, I'll remove the
1K resistors and replace with some of smaller value to see what happens.

Thanks again,
Thermo