Good advice for me too ;-) - sorry about the subject line in my previous post... ----- Original Message ----- Date: Sun, 24 Aug 2014 10:48:46 -0500 From: "drlegendre ." <drlegendre at gmail.com> Now back to your original point, the one you felt I was missing.. low, pulled down by the 470. This causes the 7404 output to go high, turning off the LED. When I connected the 330 part, Pin 41 came up to 2.8VDC (about 1/2 of VT+) which I guess the 7404 sees as a high (?) switching off the 7404 output and turning on the LED. -----Reply: Just like your misleading post about the LM309's output being connected to the 8V supply rail, you had specifically said that "there aren't *any* resistors connected to it, which is why it's sitting low. I checked that out." No mention of the 470 ohm pull-down resistor... Maybe you could save some time by checking more carefully before posting...