Electronics for Makers: LED Resistors, Dividers, ADC Scaling, Thermistors, RC Timing & PWM

What you'll build

What you will be able to do

Each lab ends with a concrete result that you build yourself and the checker confirms, cell by cell.

• Calculate the series resistor for six LEDs, pick the next standard E12 value, check the current you really get and the power the resistor has to dissipate.
• Calculate the top resistor that scales four higher voltages into the range of a 3.3 V analog input, then check the output, the current the divider draws and how much of the input range each signal uses.
• Work out the steps and volts per step of a 12-bit ADC, convert raw counts back into the battery voltage behind the divider and scale a tank sensor's counts into centimetres.
• Turn six ADC readings into thermistor resistance and temperature with the Beta equation, find the day's maximum and see how fine one ADC count is in °C.
• Calculate an RC filter's time constant, the capacitor's charge curve, the time until a button input reads HIGH and the frequency of a blinking timer.
• Turn a PWM value into duty cycle and average voltage, build a gamma-corrected brightness table for an LED and map a servo angle to pulse width and duty cycle.
• Weigh every component's active and sleep current by the time in each mode, estimate the heat in a linear regulator and work out how many days the battery lasts.
• Turn a bill of materials into order quantities with spares, look up the unit price from each part's price breaks, and calculate the cost of the run and per board.