DIY
How to Make a DeWalt Train Horn (DIY Approach)
DIY portable horn that accepts a DeWalt 20V MAX battery — and the pre-built BossHorn 2026 Boss Series alternative at similar cost.
By Train Horn Hub Editorial Published April 28, 2026
The honest answer first
BossHorn's 2026 Boss Series for DeWalt 20V MAX — see our DeWalt 20V hub — exists in Dual ($210), Quad ($265), and Extreme ($385) configurations. Building a DIY equivalent costs about the same in parts and is significantly more work. Pre-built is the better path for almost all buyers.
For the full reasoning see our parallel Milwaukee build page — same conclusion applies to DeWalt 20V MAX with platform-specific component substitutions.
DeWalt 20V MAX-specific notes
- 20V MAX is 18 V nominal — same as Milwaukee M18, Ryobi ONE+, Makita LXT under load. No platform-specific voltage adjustment needed if you've designed for 18V circuitry.
- FlexVolt 60V batteries auto-switch to 20V MAX in 20V tools — your DIY horn will accept FlexVolt packs as a high-Ah 18 V source.
- 20V MAX battery interface is mechanically distinct from Milwaukee M18 / Ryobi / Makita — you need a DeWalt-specific connector. Aftermarket third-party connector boards exist; sourcing varies.
- The Stanley Black & Decker family (DeWalt + Craftsman V20) shares similar cell architecture but mechanically incompatible interfaces. A DeWalt-built DIY horn won't accept Craftsman V20 packs without an adapter.
