Tix are no longer with us, so the only way to get one is to make one. The original can be seen in a few places on the web e.g. http://www.amazon.com/dp/B000FIB9RK/?tag=reviewsofbo0a-20
This design is cheap and simple to build, and improves slightly on the original by including a battery backup, otherwise the time needs to be reset every time power is lost.
Power is provided via USB mini connector, or by 5-12V on a pin header. A couple of push switches are provided to set the time etc. In this version an Arduino Mini is used, which needs a USB-TTL adapter for programming, in the next revision I will put a footprint to allow Arduino Micro to be used as well.
The Arduino IDE can be used to develop and download software, or if preferred an ICSP header can be added to program the Atmega directly.
Open Source (CERN OHL), designed with KiCad v4.