Batteries

The detectors work with both, single-use 9 V batteries and rechargeable 9 V accumulators. Designated as PP3 or E-Block.

The power consumption is very low, only a few milliamperes, see notes on runtime below.

Rechargeable 9V NIMH accumulators and chargers are quite cheap these days, it is recommended to use them - they'll pay for themselves quickly in comparison to the price of single-use batteries.

Recommended rechargeable 9 V NIMH accumulators

• GP17R9H => 9.6 V version (recommended for the alpha-spectrometer, resulting in a slightly larger bias voltage)
• GP17R8H => 8.4 V version

Those accumulators are rather thin (about 15.5 mm) in comparison to single-use 9 V batteries (around 17 mm thick). These thin accumulators have a particular advantage when using small diecast aluminum enclusres where the available space is very tight.

Reichelt.de is at the moment one of the best-price suppliers for the 9.6 V NIMH accumulator shipping worldwide. They also sell a cheap charger and a faster double-charger.

Runtime on batteries

Both detector variants, the alpha-spectrometer and the electron-detector, consume about 4.4 mA of current (measured at 11.5 V = a freshly charged 9.6V NIMH accumulator). With the accumulators recommended above providing a nominal value of 170 mA*hour capacity, the minimum practically observed runtime is between 30 hours with old & used accumulators and somewhat above 40 hours for brand new accumulators. Single-use batteries can provide longer run-times, up to 100 hours, largely depending on their discharge characteristic and nominal capacity.

Note on using power supplies instead of batteries

The two detector circuits are both extremely sensitive to noise and wire-bound coupling of electromagnetic interference radiation introduced by a regular, mains-connected power supply. It is in principle possible to use something else than batteries or accumulators, but only if you know precisely what you are doing (additional filtering is required etc.). Personally, I am exclusively using rechargeable accumulators for reasons of simplicity.

Note on using external batteries

If you want to connect batteries externally, outside of the metal enclosure, be aware that this may as well introduce considerable electromagnetic noise (wires acting as an antenna). Personally, I put the 9V battery always within the metal case for that very reason. It could work using a shielded cable (e.g. BNC style) but unshielded simple pairs of wires, connecting plus and minus, will almost certainly lead to problems.