160-Proof: An Audible “Parrot” Hydrometer You Can Build

Welcome! If you’re a hobby brewer or distiller—or just curious—this project turns a standard proof/trails hydrometer in a parrot into a talking meter that announces the proof out loud. We originally built it for folks with low vision, but it’s handy for anyone who hates squinting at a tiny scale while the parrot jiggles.

What it does (in plain English)

• A time-of-flight (ToF) sensor looks down a tube at the top of your floating hydrometer.

• The sensor measures the distance (in millimeters) to the hydrometer’s top.

• An Arduino converts that distance to proof using a non-linear calibration curve.

• The Arduino plays the result (e.g., “one-five-nine proof”) through a microSD audio module → LM386 amp → speaker.

• A mute button lets you silence the speaker without stopping measurements.

Core parts (one of many workable combos)

• Microcontroller: Arduino Uno

• ToF sensor: VL53L1X

• Audio storage: microSD card + microSD adapter/module

• Amplifier: LM386 breakout

• Speaker: small 8 Ω speaker

• Power: 9 V battery (tested ~7 hours continuous) or Arduino USB (5 V); the Uno can take up to ~12 V via onboard regulator

• Control: momentary push-button (speaker mute inline on the speaker’s hot lead)

• Enclosure/Tubing: PVC sleeve to sit over the parrot’s chimney

• Odds & ends: hookup wire, solder, shrink tube, small box

How it’s wired (high-level)

1. VL53L1X → Arduino: I²C (SDA/SCL + 5 V/3.3 V per your board’s requirement).

2. Arduino pin 4 → LM386 IN: audio signal line.

3. LM386 OUT → Speaker: + and − leads (speaker hot lead routed through the mute button).

4. microSD module → Arduino: SPI lines + power.

5. Power: 9 V battery to the Uno’s barrel jack or USB to the Uno. (Onboard regulator handles it.)

How it measures proof

• The ToF sensor measures distance to the hydrometer top.

• A proof/tralles hydrometer scale is not linear:

  • Near low proof (~10–20), 1 mm of movement can equal ~9 points of proof.

  • Near high proof (~190), 1 mm is closer to ~1 point.

• The firmware uses a non-linear algorithm (logarithmic terms plus constants) to map millimeters → proof.

Why the “hat” on the hydrometer?

To get rock-solid distance reads even while the parrot sloshes, we glue a small matte plastic “hat” on the hydrometer’s crown. That gives the sensor a bigger, consistent target so the beam reflects reliably.

• Material: a square of dark plastic (e.g., from an old document protector). Avoid clear/white; darker works best.

• Shape it to fit just inside your tube so it can move freely.

• Lightly etch/scuff both surfaces, then super-glue.

Important: adding the hat slightly changes buoyancy, so the visual reading on the paper scale will be a touch lower at some ranges. The audible reading is the corrected value from the algorithm.

Parrot compatibility & mounting

There are two common parrot styles:

1. Side-cup overflow (vented cup on the side).

2. Straight-tube overflow (small vent, direct outlet).

Functionally they measure the same height of float. In practice:

• One style commonly uses 2.0″ OD tube; the other 1.5″ OD.

• Slide a PVC sleeve over the parrot chimney to house the ToF sensor up top.

• Shim for a snug fit (a bit of sink-drain tailpiece tubing works great).

TL;DR: Use a 2.0″ ID sleeve for 2.0″ OD parrots, 1.5″ ID for 1.5″ OD. Shim as needed so the cap with the sensor sits centered.

Preparing the voice files

• Record spoken numbers as separate clips: 0, 1, 2, … 9, 10, 20, … 190, “proof” (and any phrases you want).

• Convert to WAV at 16 kHz (mono).

• Name them consistently so the firmware can request “160”, “1”, and “proof”, etc., then concatenate for playback.

• Copy to the microSD (root or a fixed folder your sketch expects).

At runtime, if the computed value is 161, the Arduino will fetch and play “160” + “1” + “proof”.

Power & runtime

• A single 9 V alkaline ran this build for ~7 hours continuous in shop testing.

• On USB, it’ll run indefinitely (until the host loses power).

Using the mute button

• The system measures continuously.

• Press mute to silence the speaker (it just breaks the speaker’s hot lead). Measurements and updates continue in the background.

• Press again to re-enable audio.

Build steps (quick start)

1. Print/fit the top cap with a slot for the sensor wires; mount the VL53L1X flush in the cap so it looks straight down.

2. Make the hydrometer hat (dark plastic disc), scuff & glue to the hydrometer top; let cure fully.

3. Assemble electronics on a small perfboard: Arduino + microSD module + LM386 + button + speaker.

4. Load firmware that:

   • polls the VL53L1X,

   • filters/averages readings (hundreds of samples → rolling average),

   • applies the non-linear mm→proof conversion,

   • streams the correct WAV sequence to the LM386.

5. Copy WAVs to the microSD; insert into the module.

6. Sleeve & shim the parrot so the cap sits centered; route the sensor cable neatly through the cap slot.

7. Power on (9 V or USB), fill the parrot, and confirm the spoken proof matches a trusted reference sample.

Accuracy notes & what to expect

• Around 160 proof, the hat’s extra mass may make the visual reading ~1 point off from the audible readout. Trust the audible value—that’s algorithm-corrected.

• As proof decreases, the scale gets more sensitive, so visual vs. audible differences can grow. That’s normal and why we correct in firmware.

• At very high proof, the difference is typically imperceptible.

Troubleshooting

• It keeps saying the same number: your wash may be steady—or your averaging window is too long. Reduce averaging or add change-detection hysteresis.

• No audio: check SD card format/files, Arduino pin → LM386 IN continuity, and that the mute button isn’t held.

• Jumpy readings: confirm the hat is matte, centered, and the sensor lens is clean; add a touch more filtering.

• Wrong proof across the board: rerun your calibration (see below).

Calibration (recommended)

1. Prepare reference samples at known proofs (or use a trustworthy proofing setup).

2. Record distance (mm) vs. true proof at several points across the range.

3. Fit/update the non-linear mapping in the sketch (log/exp or piecewise polynomial).

4. Re-flash and verify.

Safety & legal note

Distilling may be regulated where you live. Follow all local laws, and always operate safely (no open flames near high-proof vapors, proper ventilation, etc.).

Where to go next

• Add auto-volume based on ambient noise.

• Add a status LED (e.g., green when stable).

• Log time-stamped proof to SD for run charts.

• Add Bluetooth for readouts to your phone/watch.

Happy distilling—and happy tinkering!