Tips for using the Nixie Clock Mk2: * If no GPS unit is fitted, you will have to set the time and date manually. But before you do that, it's a good idea to decide on whether you want to use 12 hour time or 24 hour time. Also, if using 12 hour time, you may want to enable leading zero blanking, so that say at 9am it will read “9:00:00” rather than “09:00:00”. * The default is 24-hour time with no leading zero blanking. When the unit first powers up, it is already in time set mode, so if you want to change to 12-hour mode, all you have to do is hold down both buttons together for more than one second; try to press and release them simultaneously. You can then proceed to set the time and date. If you want leading zero blanking, enable it later (see below). * When setting the time and date, it's easiest to set the date first. On first power-up, the unit will be in time set mode (flashing left-hand digit). Hold down the right-hand button for more than one second and release to switch to date set mode, then set the date as described in the instructions (more tips below). Set the time afterwards – again, hold down the right button for more than one second, to switch back to time set mode, then set the time. * When setting the time, set it to a couple of minutes in the future. For example, if it's 10:09am, set it to 10:11:00 or thereabouts. Then, just before your reference clock reaches that time (say, 10:11:55), hold down the left-hand button and release it just as the time rolls over to 10:12:00 (or whatever you set the Nixie clock) to. This way, the seconds will start counting at precisely the right time. * If when setting the time or date you accidentally go past the digit you were aiming for, all you need to do is continue pressing the left-hand button until it “wraps around” back to the value you were aiming for. * To enable leading zero blanking, hold down both buttons for over one second (try to press and release them simultaneously), then do exactly the same thing again. The same procedure can be used to disable leading zero blanking, ie, this toggles the function. You won't notice the difference immediately unless the first digit of the time is zero (ie, before 10am or between 1pm and 10pm in 12-hour mode). * While the unit has provision for adjusting out any crystal inaccuracy, and the instructions give the required procedure, in practice if you want accurate time-keeping it's easier to simply fit the GPS module. In this case you don't need to worry about setting the time or date either, or adjust for daylight savings. It's all automatic. * By default, the LEDs and Nixies dim in a dark room. This is so that the clock can be used in a bedroom without being too bright at night. If you don't want this feature, or you find the dimming too aggressive, refer to the main instructions for how to adjust the dimming progressiveness. * If using a GPS module, Daylight Savings rules may change in future. If this happens you will either need to re-program the microcontroller with software that incorporates these changes or else manually set the time zone twice per year, as explained in the panel in the instructions.