Basic Electronics and Digital Electronics
Basic Electronics and Digital Electronics tests diodes, BJTs, FETs, op-amps, logic gates, Boolean algebra, flip-flops, counters, and data conversion.
Core rules
- Diode: forward drop about 0.7 V for silicon; reverse bias blocks until breakdown. Half-wave rectifier Vdc=Vm/π; full-wave Vdc=2Vm/π.
- BJT is current-controlled: IC=βIB; FET is voltage-controlled. Cut-off, active, and saturation regions define switching and amplification.
- Op-amp ideal: infinite open-loop gain and input impedance, zero output impedance. Inverting gain −Rf/Rin; non-inverting 1+Rf/Rin.
- Boolean identities: A+A'=1, A·A'=0, De Morgan (AB)'=A'+B'. NAND and NOR are universal gates.
- Flip-flops store one bit; counters divide frequency; registers store words; ADC quantizes, DAC reconstructs.
Worked example
Simplify Y=AB+AB'. Factor A: Y=A(B+B')=A(1)=A. The circuit needs no B input, so a single buffer or direct connection implements it. This is a common K-map grouping of adjacent cells.
Traps
Do not say a BJT is voltage-controlled; base current controls collector current. In asynchronous counters, each stage toggles at half the previous frequency, so the last stage is slowest. Setup and hold violations are timing, not logic-function, errors.