Make your own transceiver with a Dorji DRA818U or DRA818V

These modules have been around for a while, but they fascinate me. For only US $12,88 you get a fully functional 1 Watt transceiver working on either VHF or UHF. The last letter in the model number tells you which version it is. The modules are available on eBay from seller Dorjigroup (link).

Dorji DRA818U

Dorji DRA818U-Inside

Dorji DRA818U-Inside

Features sells PCBs including the DRA818 series:

Dorji DRA818U-3In combination with an Arduino you can build a full-featured transceiver.
Schematics below (courtesy

dra_arduino And how about a 16-channel version with a Nokia display attached?


It’s time to order these and do some soldering- and programming work. Maybe I go for a dual-band transceiver…

Links to documentation (PDF): DRA818U, DRA818V

For more information on finished projects go to, where you can find schematics and example Arduino code.

Why wireless keyboards are a bad idea

It’s a bad idea for two reasons: 1) possibility of interference (see one of my old posts) and 2) data can be sniffed.

A great example of the sniffing part is the development of the $10 keysweeper.

The “Keysweeper” looks and functions like a generic USB phone charger, but conceals Arduino-powered sniffing gear within.

The device targets Microsoft wireless keyboards and contains a host of functions allowing hackers to monitor keystrokes in real-time and have SMSes sent when certain keywords such as login credentials are typed by victims.

“Using a few-dollar Arduino and a US$1 Nordic RF chip we can decrypt these packets and see any keystroke of any keyboard in the vicinity that’s using the Microsoft wireless keyboard protocol and it doesn’t matter what OS is used.”

keysweeper_1keysweeperVery interesting project – by changing the design slightly, you could also take over someone’s keyboard. Nice for April 1 pranks! (via The Register)