VFD Modular Clock - Problem Fix Advisory and Firmware Update



We recently received an email from our customer William Phelps, who was having problems with his null. He was never able to set time and get the clock to run. After checking around a bit it turns out that a couple of his friends also had the same problem.

Not content to simply ask us to try and figure out the problem, William sat down to debug the problem. The culprit is the extra 1N4001 diode that sits between the output of the 5V regulator and the rest of the components on the board. This was added to provide extra noise reduction and isolation between the 5V power supply and the rest of the clock (both the 5V and the high voltage generator are switch mode, and generate a fair amount of noise).

This extra diode drops 0.8V off the 5V output from the 5V regulator, meaning that the entire board runs off about 4.2V. This causes problems for some DS1307 real time clock chips: They are only rated down to 4.5V, meaning that we were running it out of spec. When you do something like that, there are no guarantees, and it turns out that it caused some clocks to malfunction.

The easiest solution to this problem is to remove the second 1N4001 diode altogether and replace it with a piece of wire.

If you are having trouble with your clock, please perform the following repairs:

Cut off or desolder the right-side 1N4001 diode:

Run a small piece of wire between the two points where the diode was. You can also use a discarded piece of a leg from a resistor or a diode and solder that in place instead.

This should make the clock run properly.

PS: Even if your clock runs properly, performing this repair is still recommended.

Big thanks to William Phelps for not only pointing out the problems to us but also for spending a lot of time and effort on his side to debug and troubleshoot to help us come up with the simplest possible fix.

William is currenty hard at work adding extra features to theVFD Modular Clock Firmware. Some of his enhancements are already available for download on github, and there are even more exciting new features on the way!

PS: The Assembly instructions for the

null have been updated to skip the 1N4001 diode too. New kits will ship with only one diode.