Continuing the discussion from Make: "It's New to You" Bit:
Jude, (@JackANDJude) et al:
Your video (QVC music not-with-standing) has been my inspiration for making littleBits circuits! And although I am a HUGE Bob Widlar (inventor of the IC op amp, etc.) fan, I don't really understand the op amp (operational amplifier.) Shameful I know.
When I look under my littleBits, their backsides are lousy with opamps (they are the tiny 1.3X2.5mm dark gray rectangles with 3 solder connections on one side, and two on the other.) Opamps have something to do with almost EVERY bit!
Jude, when I look at your schematic, I find that I can also light a LED according to the voltage on the signal line without using an opamp to 'amplify' the signal. When I short out the inverting input to the output of the 741 (or any other opamp chip, I've tried about half a dozen) I get a range of outputs that echo the input voltage. Here is an experiment I did with a 741(really an NTE 941, but it's 'an equivalent'):
I notice that the output voltage, which is used to run whatever the bit does, is proportional to the input voltage, but the range from min to max is smaller. This works well with LEDs, where the Vf is typically smaller than littleBits' 5 volts, but for general signal processing, why is this useful as a bit designer?