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Nixie Clocks – Early Designs

Nixie Clock with Arduino
I got my first Nixie tubes in early 2016 and started experimenting. I didn’t know anything about then at the time, but quickly realized that they were pretty simple devices to use.

Only part that needed developing was the high voltage power supply. I did not want to use mains AC as the power source, and ideally wanted to use 5V DC so that the clock can be powered from USB.

After a bit of research I found that most of the high voltage power supply designs use boost converter driven by a PWM controller IC. A large MOSFET switching a good size inductor. Those designs looked a bit overkill to me, so I started designing my own from scratch.

Since I’m familiar with transistor based blocking oscillator circuit to boost voltage, I wanted to see if I can use similar circuit. The switching transistor has to withstand the output voltage of 180V so I picked some high voltage transistors and experimented. Turned out that typical high voltage transistors (C-E breakdown of more than 200V) were too wimpy for the purpose, and the simple two transistor circuit that I was using was not capable of very high duty cycle demanded by high input/output voltage ratio (I’d estimate close to 99%).

One way to reduce requirement for the boost converter is to add voltage multiplier at the output. I added a 3 stage Cockcroft–Walton multiplier to a circuit using pretty ordinary (inexpensive) transistors. This circuit was able to provide required voltage and up to around 3 to 4 mA of driving current to medium sized Nixie like IN-12.

While this power supply was not quite powerful enough for larger Nixie tubes, I went ahead and designed a clock circuit to get my feet wet.

Nixieduino-rev1-schematics
First design was a 4 digit clock using ATMEGA328 – I wanted to make the software easy to develop, so I loaded Arduino boot-loader. I also wanted to use the clock as a multipurpose numerical display so I added a V-USB port.

Nixieduino rev.1
This prototype had some stupid bugs, but the basic functions such as multiplexing worked. I made a revision of this prototype right after.
Second Nixie clock prototype
Nixieduino rev2 schematics
Here I experimented with a tapped inductor to effectively double the boost converter output voltage and do away with voltage doubler instead of tripler.

Are Nixie Tubes cool again?

Nixie clock prototypes
I’ve been playing/designing with Nixie tubes for some time now. I found Nixies very fascinating as the numbers inside them glow just magically.

There are many Nixie Clock designs available on the net. They are usually two types; AC main powered clock without MCUs, or low voltage DC powered with MCUs. I prefer low voltage variety because of the safety reasons, as I like exposed PCBAs.

All of the low voltage designs have some kind of high voltage (180V typical) generation circuit – and I noticed that all of the designs that I see use a pretty hefty MOSFET driven by a PWM controller IC. Somewhat complex and not so small. I kept thinking – there has to be a simpler solution.

I’m sure many people reading this are familiar with Joule Thief circuit. It’s a simple blocking oscillator based boost converter. I have done some work with two transistor variation of Joule Thief extensively, and thought I should be able to use that circuit for Nixie power supply.

Looking at the basic circuit I realize that the output voltage is limited by the breakdown voltage (Vceo) of the switching transistor. So I tried testing with high voltage capable transistors. The result was not so good – you can get the voltage, but could not deliver the current Nixies needed.

So I decided to add voltage doubler to the circuit, which looked promising. After many tries with different transistors and voltage doubler or tripler combinations I was able to come up with a supply that can deliver about 7mA of driving current into a medium sized Nixie. The circuit only uses two transistors, a not so big inductor and a few diodes and capacitors. It is much simpler and smaller than all of the Nixie power supply I have come across.

It’s not as strong (only 180V and 7mA driving current as opposed to 200+V with 10+mA) and voltage regulation is not so good. However it’s more than good enough for small to medium sized Nixie tubes. It can also work with input voltage as low as 2.4V when you don’t need much output current (i.e. miniature Nixies like IN-17).

I have designed a couple of Nixie clocks using this power supply. I will follow up with some descriptions of each stage of the designs.

Website Renewed

Some of you may have noticed that The LED Artist website has been renewed.

It was long time over due, but finally done. What pushed us to finally change the website was PayPal. They decided that it’s time to put a “hold” on our money and held it for days for no good reason. Looking back I knew that it was a bad idea to use PayPal as our main payment processor…

Now in addition to all major credit cards, we accept Bitcoin as well.

As with any new things, there might be some things that need fixing. Please let us know if you notice anything.

Collider 60 kit



Kit contents shown (LEDs not in photo, but are included in the kit)

- See Collider 60 Introduction

Collider 60 is an easy to assemble kit suitable for beginners. Relatively small number of parts are spaced apart enough so that the soldering is simple.

Please note that Collider 60 is designed to be connectable. Unlimited number of units can be snapped together like tiles, in four directions.

Features/Notes:

  • 60 white diffused 5mm LEDs
  • PIC microcontroller is preprogrammed
  • PIC24F08KL402 16 bit microcontroller @ 32 MHz
  • Dimension: 4.72 inch (120mm) square, excluding the connector protruding
  • Snappable connector to tile multiple units
  • Unlimited number of connected units

Each Kit Contains:

  • 60x white diffused 5mm LEDs
  • 1x PIC24F08KL402 16 bit microcontroller
  • 1x 10k ohm Resistor (Brown, Black, Orange, Gold)
  • 6x 1k ohm Resistor (Brown, Black, Red, Gold)
  • 3x 0.1 uF Ceramic Capacitor
  • 1x 47 uF Electrolytic Capacitor
  • 1x 1N4148 or equivalent Switching Diode
  • 1x Tactile Switch
  • 1x Piezoelectric Speaker
  • 1x 20k ohm Potentiometer
  • 2x Molex Female header (3 position)
  • 2x Molex Male header (3 position)
  • 1x Knob
  • 1x PCB

[Download]
- Circuit Schematics
- Assembly Guide

In-stock and shipping now!

Collider 60


 
Collider 60 is a very simple device – 60 LEDs on a square board, a knob in the middle. Lights run in a circle and the speed is adjustable by turning the knob.
Connect two or more Colliders and see the magic happen. When the lights run and hit the same spot at the same time, they “collide” as though they are running bullets, making clicking sound and change direction. By adjusting the rotation speed of each unit, the “collision” happens at a different interval.

The real fun starts with three or more units connected together. The results are no longer predictable.

Collider reminds us how all complex things in nature is comprised of simple roles. When you have enough number of “simple” things reacting together, you get unpredictable and interesting results.

See me at the Maker Faire Bay Area 2014

It’s that time of the year again. I’ve been working tirelessly preparing for Maker Faire Bay Area.
There will be a couple of new products introduced and on sale at special introductory prices!

Maker Faire website

R48 Battery Life Improved

After looking through the firmware very closely, I figured out a way to reduce power consumption of R48 via firmware tweaking. (Aggressive use of CPU “idle” mode while waiting for PWM pulse to output, etc.)

I managed to reduce the power consumption up to 43%. In my tests the batteries are lasting 50% or more longer!

All R48 will be shipped with the new, improved firmware as of today. If you already have R48, please send in for free upgrade.

How to receive the free firmware upgrade

  • Please send your R48 to the address below.
    The LED Artist
    12A Louis PL
    FL 2
    Brooklyn, NY 11233 USA
  • Send only the R48 unit, without batteries or chargers.
  • We will pay for the return postage. (Please pay for your postage to send in.)
  • Make sure to clearly indicate the return address.
  • The upgraded R48 will be sent back via USPS First Class mail.
  • Enjoy the longer battery life!

More Products Available at Maker Shed

I’m so excited to announce that my wearable items – A12, R48 (all colors), and USB Li-Ion Charger are now available at Maker Shed!

You can find them here.

Maker Shed also sells Color Organ Triple Deluxe II and Colour Night Joule Thief Kit.

The LED Artist wearables at Adafruit

I’m very excited to announce that now some of my LED wearables are sold at Adafruit!

See the “New Products” video – my wearables are on at 13:35.