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Project Help and Ideas » Digital Caliper Project Question

September 20, 2010
by kle8309
kle8309's Avatar

Why use a digital level shifter (by npn) and not just a use an op-amp. The output from a non-inverting op-amp doesn't invert the logic like the demo from NK.

September 20, 2010
by mrobbins
(NerdKits Staff)

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Hi kle8309,

It's simply that my preference is to use a $0.10 2N3904, a resistor, and a line of code, instead of a $1.00 op-amp (functioning as a comparator) and two resistors. It's smaller on the breadboard, and in my design sense, "simpler". However, I can certainly see how for many electronics hobbyists, using an op-amp would be "simpler". Both are fine!


January 10, 2011
by clo
clo's Avatar


I am trying to replicate the DRO project for my new mini-mill and was wondering if there was a schematic available for a three axis DRO (as mentioned as future work in the video). Also, is it possible to use the ATmega168 to process and send the positions of the three calipers to the LCD at the same time or will a different microcontroller need to be used? Also, I noticed that 3 calipers would call for 9 transistors (2N3904) and 6 MOSFETs (2N7000). Is there a way to reduce the number of components on the board (a chip that contains multiple transistors)? Thanks for the help!

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