@pusur44017: I like the Russian VFD you have selected. It was once used in an Adafruit clock kit, now discontinued. To save you some time, I have added the Adafruit schematic below:
You can also go to
this link (
http://www.ladyada.net/media/icetube/icetubeschemv1.1.png) to download a fresh copy that may be easier to read.
Looking at the number of wires coming out the end, it is apparent that the anode segments will need to be multiplexed with a high-voltage (50 V DC) driver. Some research on the world wide web could be required to see how others have successfully done this. I hate re-inventing wheels if I can find something that already works, and at least one has been successfully demonstrated. So you go look, and I will too as time permits.
The Adafruit design uses a MAX6921 driver, so that is the first place I would start. There may have been problems getting reliable parts for their kit to explain why it was discontinued, but if you can find a copy of the firmware used in the ATMEGA 168V you may be home free... build from the above schematic, download firmware. Voila! A pretty nice clock. Or you can "roll your own" design and learn a LOT of electronics along the way.
If you use the 50 Hz mains for your initial time base, you will need a small transformer to reduce the 230 VAC down to a few volts. Just about any voltage less than twenty volts or so, and greater than six volts or so, will work. Center-tapped 6.3 VAC filament transformers work well. The center-tap is connected to your circuit common. The two remaining leads are connected to the bases of two NPN small-signal transistors through a 1 kΩ to 10 kΩ 1/4 watt carbon film or metal film resistor. The two transistor emitters are connected to circuit common. The two transistor collectors are connected in parallel and then to a single 1 kΩ 1/4 watt resistor connected to a positive logic supply level (5 V for TTL or 10 to 12 V for CMOS). Zero-crossing pulses at 100 Hz will appear on the transistor collectors and should be passed to a Schmitt-trigger input logic device to produce fast rise and fall times. The pulses will bracket the zero-crossing, occurring slightly before and ending slightly after the zero crossing. Small-signal diodes should be placed across the base-emitter junctions, cathode to base and anode to common, to prevent reverse biasing those junctions. This is also a convenient way to trigger SCRs and TRIACs at the zero-crossing of the line voltage for reduced RFI with incandescent and resistive loads... not so much with inductive loads like motors though.
How it works: the transistors are alternately forward biased, 180 degrees out of phase, by positive excursions of the transformer voltage, causing their paralleled collectors to be saturated near common potential most of the time. As the transformer voltage approaches the zero crossing, both transistors turn off and a positive pulse appears on their collectors. The Schmitt trigger that follows converts these pulses into fast logic-compatible pulses. Pick a logic family before proceeding.
You should either use a fly-back boost converter for the VFD anode supply (as in the Adafruit schematic), running it from your low-voltage logic supply, or buy a "filament" transformer that also provides another secondary winding providing twenty to a hundred volts of so. You rectify and filter and possibly voltage-regulate the AC output of this winding (possibly with a voltage doubler or voltage tripler circuit if the secondary voltage is too low) to provide about 50 VDC anode power. The current requirements are modest, about 100 mA or so. I would buy the transformer, some rectifiers and filter capacitors, and perhaps a three-terminal voltage regulator just to learn about how to build a power supply. You can always switch over later to the Adafruit boost converter.
If you use the Adafruit design you can power everything from a low-voltage DC wall-wart, no transformers necessary. Timing is derived from the crystal oscillator servicing the microprocessor. You can use any solder you want, but lead-free melts at a higher temperature and is a little harder to use. It is only available because of Nanny State concerns about lead in the environment, especially landfills where consumer electronics are dumped. I have been using lead-tin solder since the 1950s. The lead melts but does liberate any significant lead fumes in the process. It is only a problem when dumped into the environment or absorbed by ingestion. Wash your hands after and don't smoke during soldering.
I thank you for the "block" diagram, handicapped as it is by your having to hand-annotate in English. Now just overlay it with the Adafruit schematic for a complete design.
On a personal note, I am handicapped by being too lazy to draw schematics (most of the time). If one picture is worth (at least) a thousand words, I opt for the words every time.
C'est la vie! Below is my unit's patch from when I served with the Strategic Air Command as a defensive fire-control systems mechanic. The bulldog represents the Gunner and the crow represents the Electronic Warfare Officer or EWO. The bulldog is holding and firing a 20mm Gatling Gun. This aft-mounted defensive armament was a radar-directed, remote-controlled, fire-control system. The crow dispensed chaff, rope, flares, and jamming signals. If that didn't work, the bulldog finished business for the day.
In the
B-52H heavy bomber, both Gunner and EWO sat side-by-side facing to the rear in the upper-level flight deck, EWO on the left and Gunner on the right (facing backwards). Every other member of the six-man crew faced forward and had some sort of view of the surroundings, although there isn't much to see at 50,000+ feet. Pilot and co-pilot sat forward at the aircraft controls and the radar-navigator and bombardier were side-by-side on the lower flight deck with both a radar and an optical bomb-sight view. There was also a fold-down seat on the upper deck for an "observer" but I never got to sit there in flight. I was not exactly a "company man" during my four-year hitch in the Air Force, so no invites to fly. The B-52H is still operational, but the Gunner position has been eliminated. The Air Force now puts its faith in electronics and air superiority to protect the BUFF from danger. So far, so good.
Hop
