A Geiger counter using a DOB-50 , OLED display and Analog meter. The meter shows CPM on a 0-25 scale with 3 LEDs (green, Amber and red ) to show multiplier. Green x 1 so 0-25 as displayed. Amber x 10 so 26-250, Red x100 so 256 - 2500 , all three blinking x 1000.
Iis all neatly sello taped into a old industrial tacho case. Runs from USB 5v. The camera on my iPad does funny things with an oled display, it's not a fault.
It uses an arduino nano (not my code , hacked from Internet ) for the oled and vu. For HV it's a 4047 astable with 3 lead transformer run in reverse 6v to 240v and voltage doubler rectification for approx 500v.