This is new, totally reworked board which can accomodate any tube, from SI-3BG through SI-37/39G upto SI-1G and even SBM-20, though the last one is a bit too large and leaves tips hanging off the board. The tube on the picture is SI-39G. High voltage generator is now controlled from the microprocessor, instead of fixed setting as on previous boards and also there’s a noisy buzzer, which ‘ticks’ just like the original geiger counter.
New software has changed a lot, now includes voltage controller, buzzer support and fast screen update. The data over USB is still sent once a minute, but the LCD display is now updated every 4 seconds (2-3 seconds were also possible, but seemed to be overkill) with the data of the last minute. Instead of fixed 1 minute intervals, this version uses “sliding 1 minute window” to calculate the value. There’s no need anymore to wait for full 1 minute to see readings go up after introduction of some radiation source, the change is obvious and imminent. Though, on the down side, this fast pace could be a bit disconcerting to some users.