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Assembly Manual
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Axiris Arduino Assembly Manual

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IV-3 VFD shield for Arduino
Assembly Manual
October 2014
IV-3 VFD shield for Arduino
Table of Contents
1 Overview 3
2 Assembly hints 4
3 PCB overview 5
4 Circuit diagram 6
5 Assembly 7
6 Final test 13
Revision History
Date Authors Description
2014-06-10 Ilse Joostens Initial release.
2014-10-12 Ilse Joostens Second release.
2 Assembly Manual
IV-3 VFD shield for Arduino
1 Overview
This Arduino shield is capable of driving 4 Russian IV-3 7 segment VFD tubes. 4 3mm LEDs provide background lighting for the tubes.
The design is completely based on through hole components, no SMD components were used. As such, the PCB can easily be assembled by anyone who has some soldering experience.
Also, the components used are cheap and easily available.
As this was designed as a more educational, easy to build project it is not the best possible solution to drive these VFD tubes from a technical point of view. Instead of the BC547 and BC557 transistors we could have used A2982W source drivers, or we could have replaced the transistors by a Supertex high voltage source driver IC with internal shift register. Unfortunately these may be hard to get and come very often in SMD packages.
Features
• Compatible with Arduino boards.
• Drives 4 IV-3 VFD tubes.
• Power supply 12V DC + 5V DC (via Arduino board, 12V supply needs to be
stabilized).
• Enclosure design (CAD files) available.
Applications
• Clock.
• Score board.
• Thermometer.
• Counter.
Assembly Manual 3
IV-3 VFD shield for Arduino
2 Assembly hints
This kit is designed for someone who has advanced experience with assembling electronics. If you believe that the kit is too complicated for your skill level please do not try to assemble it
Take your time - this kit should take 2-3 hours to complete if uninterrupted.
Ensure your work area is well lit (daylight preferred) and clean.
Assemble the board in the order as stated in the instructions - read and understand each step before you perform each operation.
It is assumed that you understand that semiconductors (diodes, ICs, transistors) or electrolytic capacitors are polarized components. Appropriate markings are silk-screened on the PCB and shown on the board schematic.
The following tools and materials will be required to assemble the PCB:
• A good quality soldering iron (25-40W) with a small tip (1-2 mm)
• Wire cutter and pliers
• Basic multimeter for voltage tests and for identifying the resistors.
• A magnifying glass to read the small device markings is often helpful.
• Solder – lead / tin solder is preferred. Lead free solder, as now required to be
used in commercial products in Europe, has a much higher melting point and can be very hard to work with. Do not use any flux or grease.
• Desoldering wick (braid) can be useful if you accidentally create solder bridges
between adjacent solder joints.
Power supply
The IV-3 VFD shield needs the Arduino to be powered from a 12 V DC power supply to function properly. Use only a regulated switching power adapter capable of delivering 12 V DC / 300 mA.
Do not use an unregulated "transformer style" wall adapter. These deliver easily more than 16 V with a light load and will cause damage to the IV-3 VFD shield as the 12 V supply voltage is quite critical.
Put some insulating tape on the metal shield of the USB connector of your Arduino before connecting the IV-3 shield to avoid solder connections touching the metal and being shorted.
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IV-3 VFD shield for Arduino
3 PCB overview
Assembly Manual 5
IV-3 VFD shield for Arduino
4 Circuit diagram
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IV-3 VFD shield for Arduino
5 Assembly
In the following pages we are going to assemble the PCB step by step. It may be helpful to keep the PCB overview and the circuit diagram at hand during assembly.
After every step, carefully compare your PCB with the pictures in the manual and check for errors and solder faults.
Diodes and IC socket
Mount the following diodes:
• D1: 1N400x or equivalent
• D2...D5: 1N5819 schottky
diode
Watch the polarity and be careful to mount the right diode in the right place.
Solder D2 and D3 from the component side and trim the wires on the solder side as short as possible as they are positioned above the metal USB connector shielding of the arduino.
Mount the 8 pole IC socket for IC1. Do not place IC1 in the socket at this stage.
Electrolytic capacitors
Mount the following electrolytic capacitors:
• C5...C8: 22µF 50V radial
electrolytic capacitor
• C9, C10: 100µF 25V radial
capacitor
Bend the leads 90 degrees and mount the capacitors flush to the PCB. Watch the polarity.
It is recommended to solder C6, C7 and C8 from the component side and to trim the leads as short as possible on the solder side as they are positioned above the metal shield of the Arduino USB connector.
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IV-3 VFD shield for Arduino
Ceramic capacitors
Mount the following ceramic capacitors:
• C1: 2n2
• C2, C3: 8n2
• C4: 100n
Please note that the values of C1...C3 are somewhat critical as C1 defines together with R5 the operating frequency of the voltage tripler and C2, C3 define the filament current for the IV-3 tubes.
10K resistors
Mount the 10 kilo ohm resistors (brown – black – orange – gold) R6...R18.
Mount them vertically as in the picture.
68K resistors
Mount the 68 kilo ohm resistors (blue – grey – orange – gold) R19...R30.
Mount them vertically as in the picture.
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IV-3 VFD shield for Arduino
220K resistors
Mount the 220 kilo ohm resistors (red – red – yellow – gold) R43...R54.
Mount them vertically as in the picture.
100K resistors
Mount the 100 kilo ohm resistors (brown – black – yellow – gold) R31...R42.
Mount them vertically as in the picture.
Remaining resistors
Mount the remaining resistors:
• R1: 510 ohm (green –
brown – brown – gold)
• R2, R3: 1 kilo ohm (brown
– black – red – gold). You may need to adjust the value depending on the tube backlight LEDs you plan to use.
• R4: 2.7 kilo ohm (red –
violet – red – gold)
• R5: 3.9 kilo ohm (orange –
white – red – gold)
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IV-3 VFD shield for Arduino
Arduino headers
Mount the Arduino stackable headers. The headers will not really be used to stack other Arduino shields on top of this shield but they help to determine the mounting height of several components and the IV-3 tubes.
Push the headers through the PCB and plug them in your Arduino. Turn upside down and solder 1-2 pins for each connector. So the connector spacing will be correct. Remove the shield from the Arduino and solder the remaining pins.
Power transistors
Mount the following transistors:
• T26: BC639
• T27: BC640
Do not replace these transistors with standard types. Mount them so that the top of their housings is lower than the Arduino headers.
Insert IC1 ICM7555 into its socket and plug the shield into an Arduino and apply power. The voltage measured between the cathode of D5 and the Arduino ground should be around 32...34V
NPN transistors
Mount the BC547B transistors T1 … T13.
Mount them so that the top of their housings stays below (or is flush with) the Arduino headers.
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IV-3 VFD shield for Arduino
PNP transistors
Mount the BC557B transistors T14 … T25.
Mount them so that the top of their housings stays below (or is flush with) the Arduino headers.
Tube backlighting LEDs
You can use 3mm standard LEDs in any color for tube backlighting purposes, even RGB color fading LEDs.
Bend the leads of the LEDs so that the LEDs fit in the 3mm holes underneath the VFD tubes, then solder them to the pcb. Pay attention to polarity. The short lead of the LED (cathode) is soldered to the pad closest to the LED name silk-screen marking (D6 … D8).
It may be necessary to insulate the leads of D9 to avoid them touching the ISP connector on the Arduino.
The LEDs are connected to a PWM output on the Arduino and can be dimmed using software. This will however not work properly when you use RGB color fading LEDs.
If it is easier for you, it is also possible to mount the LEDs after the VFD tubes are soldered in place. Due to the mounting technique, it is also easy to replace the LEDs later on if you decide you would like to have another backlighting color.
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IV-3 VFD shield for Arduino
VFD tube mounting
Guide the tube wires gently through their respective holes on the PCB. Make sure the short lead on the tubes goes through the hole without solder pad.
Now the digits should face the front of the PCB.
If you have difficulties getting the wires of the tubes through the holes you can cut them as a "spiral" so you can move 1 wire at a time through the holes. Pay attention to make the shortest wire not too short as we are going to mount the tubes with some distance from the pcb.
Once the tubes are in place align them more or less by hand. The bottom of the tubes should be approximately 1-2 mm below the top of the Arduino stackable headers.
If you are using the optional acrylic enclosure, you can use the top and bottom plates as an alignment tool.
Solder two leads of each tube to the PCB. Once this is done, you can still adjust the tube alignment by reheating the solder joints.
If you are satisfied with the tube alignment, you can finally solder the remaining tube wires in place and trim the excess leads with a small wire cutter.
Do not try to change the alignment of a tube after it is soldered in place as this may cause mechanical stress and may lead to a defective tube.
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IV-3 VFD shield for Arduino
6 Final test
Upload the demo sketch from the Axiris website to the Arduino and disconnect the Arduino from the computer's USB port.
Plug the finished IV-3 VFD shield on top of the Arduino. Make sure no metal part of the Arduino touches the solder joints of the IV-3 VFD shield.
Connect the 12 V DC power adapter to the Arduino power connector and turn the power on.
After a few seconds the VFD tubes should start counting from 0 to 9 in an endless loop. The decimal separator dots of the VFD tubes should form a binary 4 bit counter.
Tube backlighting should dim every few seconds and turn on again.
Check the tube filament wires carefully. They should glow very faintly with a deep red color. If they are glowing too much, lower the values of C2 and C3. On the other hand, if the filament barely glows and the digits are too dim, you can experiment by increasing the values for C2 and C3.
Assembly Manual 13
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