Motion Activated Dekatron Spinner

When you enter the detection zone, the Dekatron tube is activated. It will turn off some time after you leave the zone.

BOM
2 0.047Uf 400v, nonpolar capacitor

1 0.47Uf 250v, nonpolar capacitor

1 100 1/2Watt resistor

1 1K resistor

3 1N4004 diode

1 1N4007 diode

2 2.2Uf 400v polarized capacitor

1 2N3904 NPN transistor

1 33K resistor

1 5VDC relay-125V contacts

1 680K

1 68K

1 OG4 DEKATRON TUBE

1 Phone charger

1 PIR module (HC-SR501)

Acknowledgment for the core circuit used in this project goes to M. Moorrees, whose website is a wealth of information on using Dekatron tubes. See https://threeneurons.wordpress.com/dekatron-stuff/

This project uses his “Universal Dekatron Spinner” circuit, combined with a PIR module.

I chose to use an OG-4 Dekatron. I did not have the 1uF, 350V polar
caps called for in the original circuit; 2.2uF ,400Vcaps worked fine.

To save tube life, I decided
to make the unit PIR activated. To avoid building a second power supply for the +5V needed for the PIR module, I uncased a small phone charger to fit into the housing for the project. Also used a 5V relay with 125V rated contacts.

(Download Circuit.pdf for detailed image)

I wanted to fit all this into a small wooden base, originally a
lighted base for glass display. This called for a circular PCB.

(Download Board.pdf for detailed image)

Note that 3 pins of the OG-4 are not used, as they are not connected
to anything internally.

(Yes, I still manufacture my own boards,because it is fun!)

Plexiglass bottom shields access to high voltage but allows access to PIR module for adjustments.