PCB design for pen-sized nRF52840 BLE audio recorder + charging case
Budget / Salary₹150,000–250,000
TypeFreelance project
LocationRemote
Posted1 hour ago
PCB designer needed for a pen-sized nRF52840 Bluetooth audio recorder and its charging case (rigid-flex), pilot run of 5-10 units, Bengaluru, India.
THE PRODUCT
A working ballpoint pen (12.5 mm diameter, ~153 mm long) that records conversations to onboard flash and syncs to a phone app over Bluetooth Low Energy. It also logs motion-sensor data. It snaps magnetically into a charging case with its own battery. Proof of concept already works on a Seeed XIAO nRF52840 Sense. Detailed drawings and firmware shared after an NDA.
BOARDS (pen boards must fit a ~10.9 mm inner diameter)
1. Pen main board ~8 x 30 mm, both sides populated, under a translucent antenna window
2. Flex cable ~90 mm down the barrel past the battery
3. Sensor disc ~9 mm round behind the refill (IMU + nib force sensor)
4. Case board ~8 x 10 mm (USB-C in, case LiPo charging, pen charging via pogo pins)
Pen battery 10350/10440 Li-ion; case battery ~5 x 17 x 80 mm LiPo (~700 mAh).
STARTING PARTS (suggestions welcome): nRF52840 module or bare chip + chip antenna; 1-2 PDM MEMS mics; 64-128 MB SPI flash; 6-axis IMU (LSM6DSO/BMI270); Li-ion charger + fuel gauge + protection with very low sleep current; centre + ring charging pads with magnet; LED ring; one button. Case: charger IC, charge path to pen pins, gauge, Hall sensor, status LED.
Targets: full day of recording, weeks of standby, 5 m+ BLE range from a mostly aluminium pen.
DELIVERABLES
1. Architecture review of part choices (week 1)
2. Schematics for all four boards
3. Layouts, stack-up and flex design, Gerbers, BOM, pick-and-place for JLCPCB assembly
4. 3D STEP models of each board
5. Bring-up support for prototype round 1 and one revision for round 2
6. Native source files (KiCad preferred, Altium OK)
Timeline: schematics ~3 weeks, layouts ~week 6, round 2 ~week 12.
TERMS: NDA; all design files and IP assigned to us; milestone payments; a small paid first task (review our parts list and block diagram) before the main contract.
TO APPLY: share 2-3 small battery-powered boards you designed that reached a real product (photos; nRF52 or rigid-flex a strong plus), a quote broken down by the milestones above with earliest start date, your design tool, and your location / whether you can meet in Bengaluru.
THE PRODUCT
A working ballpoint pen (12.5 mm diameter, ~153 mm long) that records conversations to onboard flash and syncs to a phone app over Bluetooth Low Energy. It also logs motion-sensor data. It snaps magnetically into a charging case with its own battery. Proof of concept already works on a Seeed XIAO nRF52840 Sense. Detailed drawings and firmware shared after an NDA.
BOARDS (pen boards must fit a ~10.9 mm inner diameter)
1. Pen main board ~8 x 30 mm, both sides populated, under a translucent antenna window
2. Flex cable ~90 mm down the barrel past the battery
3. Sensor disc ~9 mm round behind the refill (IMU + nib force sensor)
4. Case board ~8 x 10 mm (USB-C in, case LiPo charging, pen charging via pogo pins)
Pen battery 10350/10440 Li-ion; case battery ~5 x 17 x 80 mm LiPo (~700 mAh).
STARTING PARTS (suggestions welcome): nRF52840 module or bare chip + chip antenna; 1-2 PDM MEMS mics; 64-128 MB SPI flash; 6-axis IMU (LSM6DSO/BMI270); Li-ion charger + fuel gauge + protection with very low sleep current; centre + ring charging pads with magnet; LED ring; one button. Case: charger IC, charge path to pen pins, gauge, Hall sensor, status LED.
Targets: full day of recording, weeks of standby, 5 m+ BLE range from a mostly aluminium pen.
DELIVERABLES
1. Architecture review of part choices (week 1)
2. Schematics for all four boards
3. Layouts, stack-up and flex design, Gerbers, BOM, pick-and-place for JLCPCB assembly
4. 3D STEP models of each board
5. Bring-up support for prototype round 1 and one revision for round 2
6. Native source files (KiCad preferred, Altium OK)
Timeline: schematics ~3 weeks, layouts ~week 6, round 2 ~week 12.
TERMS: NDA; all design files and IP assigned to us; milestone payments; a small paid first task (review our parts list and block diagram) before the main contract.
TO APPLY: share 2-3 small battery-powered boards you designed that reached a real product (photos; nRF52 or rigid-flex a strong plus), a quote broken down by the milestones above with earliest start date, your design tool, and your location / whether you can meet in Bengaluru.
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