A button chain is essentially a resistor chain and the world’s most popular timer IC, the 555, produces a sound corresponding to each press directly to the speaker. Runs on a single 9V snap battery.

• operating voltage: 9VDC
• current consumption max. 75mA (5mA at idle)
• thirteen buttons
• by changing the chain's resistor values you can switch the note scale as you wish
• PCB dimensions: 106 x 32 mm
• includes Ø 57 mm small speaker (8ohm 0,25W)