Vacuum Florescent Display question

Thread Starter


Joined Jan 27, 2015
I pulled 1 from a stereo, with the PCB and controller chip. I can't find a datasheet, but had the IC working with 5V anyways.

As for the VFD, does it really need AC on the cathode, like a heater winding for vacuum tubes ? The transformer from the stereo did have some low voltage windings, like 4Vac, or 10Vac, I have it here, but the stereo is long gone and IDK for sure what trans it was, both trans had LV windings like cathode heater level.

In an EEVblog video, Dave used AC. Then in another video a guy used 3V DC. If the filament is just a resistor, and the RMS power is the same, and the voltage is low enough relative to the anode and grid, should it be ok ?


Joined Apr 5, 2008

From the wiki:
The device consists of a hot cathode (filaments), anodes (phosphor) and grids encased in a glass envelope under a high vacuum condition. The cathode is made up of fine tungsten wires, coated by alkaline earth metal oxides, which emit electrons when heated by an electric current. These electrons are controlled and diffused by the grids, which are made up of thin metal. If electrons impinge on the phosphor-coated plates, they fluoresce, emitting light. Unlike the orange-glowing cathodes of traditional vacuum tubes, VFD cathodes are efficient emitters at much lower temperatures, and are therefore essentially invisible.[6]