To listen to content, news and other stuff using BT headphones while working in various areas around here I have improved the Bluetooth coverage from the main computer.  We are in a high BT usage area.  Neighbors with dozens of phones, tablets and appliances.  BT can be a bit unreliable at times.

Relocate Bluetooth Dongle

Increasing BT coverage worked by using an active USB extender and mounting a BT dongle with external antenna in a central location with minimal obstruction to the main work areas.

The BT extender provides four USB 2.0 ports extended over a network cable using a transmitter at the computer and a receiver in the remote box.

The extension is about 15 meters.  Attached to the cctv camera mount.

Improve the BT Headphones

The Zealot B19 headphones are not the latest but they are low cost and robust for a work environment.  They also work well with glasses. 

The problems are a terrible battery charging circuit and limited run time between charges.  The standard battery is a CS-NK5BHL 900mAh Li-ion and can be easily replaced.  The charging circuit is just a diode and 2.2R resistor off the 5V USB supply which overcharges and destroys the battery after a while.

This solution attaches an additional 18650 cell and improved charger module.  Allowing overnight charging and all day runtime.

A 1 ohm resistor connects the the two batteries limiting current flow if charge states differ when connecting.  The external 18650 cell is attached to the headband.  A few components are removed from the main board (diode, resistor, transistor) and the charge module installed between the USB connector, battery and main board.

The 2 LEDs on the charge module roughly align with the original indicator light pipe – so that was convenient.

Ear Pads

The original fake leather plastic pads fall apart when being used all day and cannot be cleaned.  These can be replaced with fabric and foam pads for a few $ that can be washed in warm soapy water and don’t fall apart.

History

I have been using an old pair of Zealot B19 headphones for years with  the same modifications.  Pairing and connecting was a PITA, possibly due to the early BT version and HID specification.  Once paired they worked quite reliably, occasionally dropping the connection due to nearby electrical interference (inductive motor switching).

These new B19 headphones advertise BT 5.2 and we’re using a BT 5.3 UBS dongle.