Logic probe

Project Logic Probe
voor metingen aan diverse digitale apparatuur heb ik een logic probe nodig, dus heb ik er een gebouwd
Status	Completed
Contact	Mahjongg
Last Update	2017-09-06

For among other projects like my RHOCOCCO project one handy measurement device to quickly check digital logic is the digital logic probe. You can buy one, but its much nicer to simply create your own. Its more a mechanical challenge than an electronics challenge, as the electronics consists of little more than a CMOS quad NAND chip and a couple of leds and a few resistors. Interestingly the first of the four NANDS is used in analog mode by using a large feedback resistor from output to input. The probe, after some puzzling works. Only thing I did not expect is that the input is instable, resulting in the continuous burning of the yellow pulse LED. The instability is probably caused by my attempt to more or less shield the input wire causing a parasitic capacitance on the input.