S5-4.3 555 Timer, Voltage Regulators & Data Converters
You can use the 555 in monostable and astable modes, analyse and design a regulator with IC723 and use IC7805, and compare weighted-resistor and R-2R DAC and comparator, successive-approximation and dual-slope ADC architectures.
The 555 is the most-produced integrated circuit in history and its two modes cover an enormous amount of practical timing work - learn the RC expressions well enough to design to a period rather than look one up. Among the converters, the comparison is the content: flash is fast and expensive, successive approximation is the balanced workhorse, dual slope is slow but rejects mains hum, which is why it lives in multimeters. R-2R exists because fabricating many precise resistor values is hard while fabricating two is easy.
Work through these
555 timer functional diagram
The most produced integrated circuit in history, and worth knowing from the inside. The internal comparators and flip flop explain both modes below, so spend a minute here first.
Monostable mode of operation
One pulse of a length you choose. Learn the timing expression well enough to design to a period rather than look one up.
Astable multivibrator operation
Free running oscillation, and the mode you will reach for most. The asymmetry between the charge and discharge paths is what sets the duty cycle, and it is the detail people miss.
Voltage regulator IC7805
The three terminal part that makes a fixed supply from a rough one. Almost too convenient to think about, which is why the next item exists.
Analysis and design of a voltage regulator using IC723
The adjustable version, where you actually design rather than drop in a part. It is the item that teaches what a regulator is doing internally.
Data converter specifications
The vocabulary for comparing converters, and the thing to settle before the two items below. Resolution, accuracy and speed are not the same promise.
DAC: weighted resistor and R-2R ladder
Two ways to build a converter from resistors. The ladder exists because fabricating many precise values is hard while fabricating two is not, which is a manufacturing argument rather than a circuit one.
ADC: comparator type, successive approximation, dual slope
Three architectures and the comparison is the content. Flash is fast and expensive, successive approximation is the balanced workhorse, and dual slope is slow but rejects mains hum, which is why it lives in multimeters.
Lab: implement astable and monostable multivibrators using IC555
The bench version of the timer. Building both modes from the same part is what makes the internal block diagram worth having read.
Lab: implement low and high voltage regulators using IC723
The bench version of the regulators, at two voltage ranges. Loading the output until it drops is the measurement that teaches the most.
Lab: implement an R-2R ladder DAC and an ADC
The bench version of the converters. Seeing the staircase come out of the ladder is the moment the resistor argument above becomes real.
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