Level 2 · Sound — TinyOhms

Door Buzzer Your first sound circuit — a real doorbell for your bedroom door. 20 min · ●○○○○

Dial-a-Brightness Twist a knob and watch the LED fade up and down — your first "how much" input. 20 min · ●●○○○

Dial-a-Buzz Dial-a-Brightness for sound — one knob rides the buzzer between full alarm and library silence, with no button in the way. 15 min · ●●○○○

Continuity Tester Your first real tool — two probe wires that beep and light up whenever the tips touch anything that conducts. 20 min · ●●○○○

Panic Doorbell Two buttons wired so either one fires the same buzzer and light — your first OR gate. 20 min · ●●○○○

Whisper Alarm A doorbell with a volume knob — the pot lives in the buzzer lane, so twisting it changes the beep without touching the light. 25 min · ●●○○○

Two-Tone Doorbell Two call buttons, one doorbell: LOUD rings the buzzer and lights the porch LED; QUIET starves the buzzer and shows why it can't just be dimmed. 25 min · ●●○○○

Arm & Ring A doorbell that ignores you unless a hidden slide switch is armed first — series-AND with sound, plus an 'armed' LED that shows the state. 20 min · ●●○○○

Twin Bells One doorbell button rings two buzzers in parallel — one in your room, one in the kitchen — with a slide switch that mutes just the bedroom bell at night. 20 min · ●●○○○

Two-Hand Bell Two push buttons in series feeding a buzzer and an LED — both hands must stay pressed for the alarm to sound. 20 min · ●●○○○

Silent Alarm Three panic buttons wired in parallel, all inside an armed lane — any one of them fires the buzzer, and a small LED tells you the alarm is watching. 25 min · ●●○○○

Quiz Buzzer Two teams, two big buttons: yours lights your LED and rings your buzzer, theirs does the same on their side. Two independent doorbells sharing one battery. 20 min · ●●○○○

Level 2 · Sound

New in the box

Projects at Level 2

What you can build so far