Single Digit Nixie Tube-in-a-Tube Clock

A glass test tube case is used to fit this single digit Nixie clock using minimal component count and without the difficulty of obtaining high voltage transformers & transistors, inductors, and driver ICs.

The nixie of this clock directly takes its high voltage supply from the mains but with some serious implications with respect to safety. As long as a completely isolated case is used and the metal parts of the circuit can be touched while connected to the mains, the clock is completely safe. The mains ON/OFF switch in this case is a simple cord switch for safety reasons and the case uses an elegant glass test tube.

A PIC16F628 microcontroller was used to process the activities which was configured to run on its internal 4MHz oscillator which eliminates the need for a crystal or resonator since the timing of the clock uses the 50Hz mains frequency. The MCU consumes around 0.5mA at a supply voltage of 4.5V and 4MHz clock frequency.

The software is created to simultaneously perform different tasks such as producing a sequence of random colors in ambilight LED, driving the nixie tube, time tracking, and filtering mains signal.

Rest of the project