VFD-Tube Thermometer

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

http://tubes-store.com/product_info.php?products_i...

Microcontroller : I used At89s52

IC: UDN2981

StepDownConverter: LM2596

Thermometer: DS1621

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.