SparkFun Audio Amplifier Kit - STA540

A stereo audio amplifier kit built around the STA540 power amplifier IC. Once assembled, you get a fully functional two-channel amplifier with standby switch, volume control, and indicator LEDs. Configured as a dual bridge amplifier, it delivers up to 2× 38W into 4Ω speakers at 18V.

All components are through-hole, making it accessible for intermediate soldering skills. A 6400BG heatsink is included for thermal management. Power the board with 8–22V DC and connect your speakers via screw terminals.

Key Features

• 2× 38W Output – Dual bridge configuration (4Ω at 18V)
• Stereo Channels – Two independent audio channels
• Volume Control – On-board trimpots for adjustment
• Standby Switch – SPDT switch for standby mode
• Status LEDs – Three red indicator LEDs
• Heatsink Included – 6400BG heatsink for the STA540
• Through-Hole Kit – All components are through-hole for easier assembly

Specifications

• Amplifier IC – STA540 (dual/quad power amplifier)
• Op Amp – LM358
• Output Power – Up to 2× 38W (4Ω, 18V)
• Power Supply – 8–22V DC
• Output Connections – 2-pin screw terminals (3.5mm)

Kit Contents

• 1× STA540 Audio Amplifier Kit PCB
• 1× STA540 Dual/Quad Power Amplifier IC
• 1× 6400BG Heatsink
• 1× LM358 Op Amp
• 3× Red LEDs
• 1× SPDT Mini Power Switch
• Resistors: 5× 10kΩ, 3× 1kΩ, 2× 47kΩ, 2× 100kΩ, 2× 10kΩ trimpots
• Capacitors: 1× 1000µF, 1× 100µF, 4× 0.47µF, 3× 1µF, 1× 0.1µF, 2× 10pF
• 5× 2-Pin Screw Terminals (3.5mm)
• 4× Nylon Standoffs, 5× Phillips Screws, 1× Hex Nut

Resources

• Assembly Instructions (PDF)
• Schematic (PDF)
• GitHub Repository