Deluxe Geiger Counter Circuit: This unique Geiger counter circuit is ready to go. It has many amazing features not found in other counter, including the ability to handle a enormous number of different Geiger muller and some neutron tubes due to its easily adjustable output voltage (260vdc to 950vdc).It was custom-designed to be small, measuring only 3.1" x 0.79" (79mm x 20.0mm), and at a little over half an inch high. Assembly into any kind of case, from a breadboard, to a cigar box, or to a custom-made handheld enclosure, is a cinch, . The original circuit was Custom Re-Designed to use the same advanced SMD technology found in Smart Phones everywhere today. Operates on 2.5vdc to 5.5vdc, and works extremely well with the same 3.7vdc lithium-ion batteries used in cell phones and other smart devices. It comes complete with hook-up instructions and other data, making it project-ready for even the most novice of Geiger counter enthusiasts. Limited Quantities.