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📚 User Guide

What you are holding​

A wooden European nightjar (Caprimulgus europaeus) made of beech. Inside it has a speaker and a small player. When the wooden button is pressed, it plays a recording of a real nightjar – the “churring” heard on warm summer nights at the edges of pine forests. The nightjar is a nocturnal bird and by day it sits motionless along a branch – exactly like this one.

Use​

  1. Plug the button into the socket in the tail (a 3.5 mm jack).
  2. Press the button. Within 3 seconds a sound is heard (≈ 7 s). Then the nightjar falls silent and “sleeps” – in sleep it draws nothing.
  3. If instead of the sound the green light behind the grille on the chest blinks 3× – the battery is weak.

Replacing the battery (like a CMOS battery in a computer)​

Charging and service – no hatch

  1. Turn the nightjar onto its back. On the belly there is a wooden hatch – lift it with your fingernail by the groove (it holds on magnets).
  2. Take out the cell (type 16340, 3.7 V Li-ion, with protection). Insert a charged one: the flat pole (+) onto the flat contact, − onto the spring – the polarity is burnt into the wood.
  3. Close the hatch. Done – nothing needs to be set.
  4. Charge the discharged cell in the supplied charger (2–3 h). Never charge a damaged cell; do not throw it in the rubbish – it belongs in battery collection.

One charge lasts hundreds of playbacks, or many months at rest.

Battery safety – please observe​

  • Use only a protected 16340 cell from a known brand – the kind that was supplied. No other types, no unverified sources.
  • A cell with a dent, a damaged wrapper or one that got warm during charging – do not use; hand it in to battery collection.
  • Never charge the cell in the nightjar. Only in the supplied charger, on a non-flammable surface, not unattended.
  • Do not leave the nightjar in direct sun, on a radiator or in a car.
  • If the nightjar is warm near the hatch or you smell something – open the hatch, take the cell out onto a stone/paving and do not use it any more.

Inside, the cell is protected by its own protection circuit, a current (PTC) and a thermal fuse and lies in a non-flammable lining – the only thing it needs from you is the right type of cell and charging outside the nightjar.

Replacing the recording​

  1. Open the battery hatch, take out the cell.
  2. With tweezers gently press the microSD card in the slot next to the holder – it pops out.
  3. On a computer replace the file /mp3/0001.mp3 with another MP3 (I recommend 6–10 s, mono, 128 kb/s). The card must stay FAT32.
  4. Put the card back (contacts towards the slot, it clicks), insert the cell, close the hatch.

Caring for the wood​

  • Wipe with a dry cloth. Do not wash with water.
  • Once every year or two apply a thin layer of wood oil (Osmo / linseed), wipe off after 15 min.
  • Do not leave in direct sun or near a radiator.

FAQ​

  • It does not play and does not blink. The cell is completely discharged or inserted the wrong way round. Check the polarity, try a charged cell. If that does not help, the thermal fuse may have blown (after overheating) – that is a service intervention, get in touch.
  • It plays quietly / crackles. The cell is at its end (below 3.5 V) – replace it. Or the grille is clogged with dust.
  • It plays, but only sometimes. Check the button jack – pushed all the way in? Is the cable OK (multimeter)?
  • I want a different sound. See “Replacing the recording”.
  • Where is the recording from? From the xeno-canto database (number XC…, author …, licence CC …) – stated in the project documentation.

Using version v7 (5 Oct 2026)​

  • Playing: press and hold the button; the sound is heard after a short start-up of the module, releasing stops it. On a long hold the recording repeats.
  • Charging: only via the TP4056 module (micro-USB, a channel in the tail), 1.5 to 2 h; do not charge unattended.
  • Replacing the recording: /lelek.mp3 via the USB-C of the DFPlayer Pro module, battery disconnected.

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