• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Need VFD display filament driver

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Rundmaus

Rundmaus

Member
Joined 2005
Doz said:
Whoa, IIRC, the filament on VFD's is normally 3 volts, and -30 applied to the cathode to illuminate the segment.
Click to expand...

Hey there,

for VFD as well as for other tubes, the (electron emitting) filament *is* the cathode.

But you are partly right, one has to distinguish between the voltage/current to heat the filament (probably a few volts) and the 'anode voltage' between the filament and the rest of the display - this will probably be the 30V mentioned.

A datasheet for the VFD would help! ;)

Greetings,
Rundmaus
 
A

avi198617

Member
Joined 2010
Hellow to all,
The unit I am building is getting its supply from DC wall adapter & it is better if I avoid usage of transformer.

I had came across some Chinese amplifier where I found this VFD & its driver IC.
There they had used two additional winding of 3V/0.3A,28V/0.2A. For my case,
I need some converter chip to generate those from 3.3V.


I had attached VFD datasheet on previous my post:(..but it was bigger then the size mentioned. Anyways attaching only the relevant pages in JPEG form.
 

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Q

quadtech

Member
Joined 2007
There are many many ways to skin this cat.

I built this clock based on an Atmega8 and a Soviet IV-18 (IW-18) VFD display.
It uses a simple capacitor multiplier from a 12V AC walwart for the Grid voltage.

Zegar i termometr na IW-18

59_1240581084.jpg


Some circuits like Riad S Wahaby's inGrid use a PWM from the
microprocessor to generate the VFD voltage.

inGrid IV-18 VFD clock
Application notes and Y Series how to guides

Limor Fried (Lady Ada) has a very beautiful IW-18 clock, and has put
up comprehensive documentation on the processor driven converter.

http://www.ladyada.net/make/icetube/
http://www.ladyada.net/make/icetube/design.html

65_1264883025.jpg


555 based boost converter...
Zegar VFD na lampie IW-18 [AVR] sid.devBlog();

MC34063 based converter -

82_1251912627.jpg


PipeBOMB - zegar VFD,lampa IW18,Pilot, BlueTooth, sync. SNTP
 
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M

mbates14

Member
Joined 2002
Sorry to pull up an old thread, you can keep it entirely solid-state without any transformers or coils. Using a power op-amp or audio amplifier IC, you can drive the filament AND a diode/capacitor ladder circuit at the same time, to power the VFD.

Drive the audio amplifier/power op-amp with a square wave generated by the micro, using the same timer as the one that does the multiplexing interrupt, this will keep things in sync and eliminate beat artifacts entirely.

The filament is coupled to the op-amp via capacitors, this will allow you to float the filament at wherever for cut-off.

If you wanted to keep filament voltage, and anode voltage independent, then you could built a boost circuit and a op-amp filament drive circuit seperate, and use 0C1A/0C1B both from the same timer. They are in sync, but independent adjustment PWM.
 
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