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Davac 4.1 OK1ZIA

Warning Warning:

This design is obsolete, look at current version

Davac 4.1 is updated version of Davac 4.0 designed in 2008.


  • IRLML2246 instead of IRF7220
  • Silkscreen cleanup
  • Values on silkscreen
  • Jack holes are 2 mm
  • Guard ring connected to GND
  • Manufacturing data for jlcpcb.com included


  • Optocouplers are TLP627, not PC817 (error during convert Eagle -> KiCad)
  • Headphones have GND connected to hot and vice versa. I recommend skip REL2 and connect radio to headphones directly

Circuit diagram

Circuit diagram of Davac 4.1


Davac4.1-jlcpcb.zip Gerber files to order PCB at jlcpcb.com.

If you have extra pcs and want to help other Tucnak users, let me know, I will announce here.


Transformer TR-1/1 www.tme.eu

Jack 6.35 K3606D www.gme.cz or K36092B

White connectors for cable pins

Black connectors for cable flat cable

Program the FT232R

As default, the FT232R acts as serial port. But Tucnak uses Libftdi to access it in bitbang mode. Default VID:PID must be changed to distinguish Davac from other USB serial ports.


Use ft232r_prog.


# ft232r_prog --new-vid 0xa600 --new-pid 0xe110 --manufacturer OK1ZIA --product 'Davac 4.0'
Rewriting eeprom with new contents.

Now replug the device

# lsusb
Bus 002 Device 007: ID a600:e110 Asix OK1ZIA Davac 4.x

In the case of mistake, use --old-vid and --old-pid. AFAIK this can be used also to fix fake FT232 bricked by Windows FTDI drivers.


MProg with loaded Davac4.ept

Under Windows, use MProg. Download File:Davac4.ept and open it in MProg. Note on Windows XP you need D2XX drivers; on newer versions they are installed automatically.

Unplug all other FTDI devices and press the Program All Existing Devices button.

Install USB drivers


You have nothing to do, It will work automatically. Only on specific distributions you may have to set permissions to USB device, which is normally done by udev script.


Zadig with Davac4

Under Windows 7 or newer, use Zadig. On XP use 2.2.

Click Options, List All Devices.

Choose WinUSB and press Install Driver.