You’ve built the kit, you have your GM tube, now how do you get your Geiger counter into the field and have some fun? Obviously, you have to package it. From the infinity of possibilities, where do you turn? Do you want the GM tube (detector) in the enclosure, or remotely located? How much battery life do you think you’ll need. What features of the kit do you want to be front-panel configurable? The possibilities can be overwhelming.
This post covers a simple, yet compact packaging of the GK-B5 kit by DIYGeigerCounters. The display and electronics are mounted on the front-panel with the only relocated component being the speaker (also mounted on the front panel). There is room in the 5″ x 2.5″ x 1.5″ project box for an SBM-20 GM tube, but I’ve opted for interchangeable remote sensors attached via BNC connection.
There are a couple of modifications I performed during the build that may be interesting. The first, is the replacement of the 78L05 regular with Pololu up/down voltage regulator (also available on the DIYGeigerCounter website). This allows the kit to run from a single-cell (3.7V) LiPo. Instead of mounting the Pololu regulator on the bottom of the board, I mounted it on the top, vertically:
Boost VREG
The regulator is to the right of the green input power screw terminals, and is mounted using a 3-pin 90-degree header. A notch in the green power connector had to be made, but the screw terminals could be omitted all-together by soldering the power wires directly to the board. Also notice the two-pin female header the LED is plugged into. This allows the electronics to be unplugged from the display, which is hot-glued to the front panel (more later). On the lower left is a JST charging connector for the LiPo cell, which I salvaged from an aircraft “accident”. NOTE: When using LiPo’s, it’s best to get one that has under-voltage protection circuitry built-in. This will keep the cell from being permanently damaged if discharge is attempted below 3.2 volts or so.
Looking at the back side of the front panel, the display cut-out was made with a nibbling tool, and filed into final shape. The LED, speaker, and IR sensor are glued to the panel, with the power switch on the right:
Rear of front panel
Now, the display is hot-glued to the front panel:
Display mounted
The electronics are then plugged into the display board, with the LED & IR sensor pins plugging into their respective sockets on the board. A couple of wires are run from the electronics board to the speaker. The power & detector wiring is shown installed. There is still room on the front panel for more switches to control operational parameters of the GK-B5. I didn’t quite get the display in the correct position (too far left), so I had to trim a bit off the circuit board near the power switch (measure 2x, cut 1x):
Electronics on the back of the display
The LiPo is affixed to the bottom of the project box with double-sided adhesive, and a piece of DU-BRO 1/2″ foam is sandwiched between the electronics and the battery to keep the electronics firmly pressed against the display. Adding a little contact paper to the aluminium front gives a nicer finish.
And that, as they say, is that. If I had it to-do over again, I’d put the contact paper on BEFORE mounting all the components. The completed detector & electronics fits together thusly with a piece of RG-59U (75 ohm) coaxial cable and BNC connectors:
Electronics & detector
John has several good links to articles on his website.