3-bit Analog-to-Digital Converter
2,808 views · Published 8 July 2012 · 1:10 · Indexed 11 October 2026
Channel: Paul Nathan · 2012 · Education
A circuit to divide an input signal into 2^3 = 8 levels and light up a bank of LEDs indicating the quantised level. Using a potential divider cascade the 12V reference voltage was divided up into 12/8 = 1.5V blocks. Each level was fed into the non-inverting input of a comparator (here just an op-amp running in open-loop mode). The inverting input of all comparators was connected to the signal input, itself buffered to prevent any current draw from the signal source itself. Thus when any inverting input exceeds the non-inverting input reference level the op-amp goes low and this provides a current path for the appropriate LED. The circuit was powered by the LM317 DC regulated supply circuit presented in the previous video. Also I coupled this circuit with the alarm threshold circuit from the previous video, with the threshold here set to 9V (LED no. 6).
