Repeat 8 times: take a BS250P PMOS and solder the S, G and D pins to the board (S to the Vcc bus) and a 10K resistor between the G and the S (or the Vcc bus). Let's label the Gs and Ds (G'0, D'0), ..., (G'7, D'7), respectively. Take a BS170 NMOS and...