#Trash to treasure

Which part is made from scrap?

One end of a two-metre galvanized pipe is cut at an angle and a steel plate is welded on tilted about 45° (like a small hoe); a handle is welded on wherever it feels right. Four holes in the plate take two bearings (as close to one straight line as possible), a shaft goes in and the excess is cut off, then an adapter, clamp plate and small pulley are fitted. A bracket for the 775 motor is welded on; once cool, the 775 motor and belt go on, and a powered test shows it runs smoothly. For power, 18650 cells make a 3S5P pack with a balancing BMS, fitted into a box with input / output / gauge / switch holes cut in it; the charge input gets a CV/CC buck-boost module with charge management set to about 12.8V; the battery positive runs through the switch into a boost module set to 33V feeding the 24V 775 motor — more torque and more speed. The box is fixed to the tail of the pole, the output lead connected, a shoulder strap tied on and trimmer line fitted (soft wire for now). A test cut at the front door works well — lighter and quieter than a petrol trimmer.

An old powered speaker picked up at the scrapyard (under ¥1); fuse good, a hum on power-up, transformer output normal. The plan was to feed the Bluetooth module’s audio output into the original board’s audio input, but it didn’t amplify; switched to driving the speaker straight from the Bluetooth board, which works. So everything original except the driver comes out and it becomes rechargeable — 6 × 18650 spot-welded into a pack with a 3S60A balancing BMS, fish paper insulation and fibre tape; a diode and a CC/CV buck module on the charge side; a fast-charge port, charge-level display module and switch in the case; wired up, powers on, back in the case, phone pairs and plays, ‘sound quality is decent for its size’. The top comment points out that without audio amplification the result is only so-so.