This is a short tutorial about my VFD-Tube Thermometer. I build it because I liked a indoor thermometer that nobody had, except me.
I used the VFD-Tubes because I like the retro style.
For temperture measure I used a DS1621 connected to a AT89S52 with I2C-Interface, the Sorce-Code is programmed in C. I measure the temp at 0.5° Steps
The case is a selfmade wood-case.
Step 1: What You Need
What you need:
Tubes: IV-11 and IV-3
Microcontroller : I used At89s52
Wires and circuit board
I bought the parts at www.reichelt.de
Step 2: Buying and Testing the Tubes
At first I order some VFD-Tubes from rusia. The Thermometer uses iv-11 tubes.
Then I made some test to conrol the VFDs. At the picture you can see how I connect my IV-11-Tube.
I run the VFD-Tubes at 18V and for controlling the Signals from 5V (Output of the MC) to 18V I use the UDN2981 IC.
At my first run I used a 7805 for genarting the 5V for the MC later I changed it to a Step-Down-Modul LM2596 because the 7805 generated a lot of heat.
Step 3: Explain My Circiut
At the picture you can see how i placed the Parts.
I used a LM2596 for generating the 5V for the MC
The tubes are working with 20V but the MC only can use 5V so I used a UDN2981 for changing the Voltage from 5 to 20V.
Step 4: Writing the Sorce-Code
For controlling the VFDs I used a AT89s52.
The temperture is measured by a DS1621.
I wrote my own I2C-Code but you also find a lot of ready I2C-Libaries that you can use for the communication to the DS1621.
For Programming I used Atmel Studio.
Step 5: Finishing
At last I build a case and added some LED´s for a backlight.
I also made the DS1621 to the outside to get a better ambient-temerature-measurement.