9
2.4 Transistors
NOTE - Updated April 2021
The transistors are easy to install - just bend the leads, and solder as usual. However, please take
note of the orientation of the 2N3906 transistors, which may not match the silkscreen.
On PCBs labeled version 2.2 and earlier, the
silkscreen orientation is reversed. While the
seven-segment display will still work with
reversed transistors, it will be much less bright.
On all versions of the PCB, the 2N3906
transistors should be installed with the flat side
facing *away* from the top edge of the PCB. This
will greatly increase the display brightness (and
also the electric current usage of the module -
adding roughly 60mA at peak).
The 2N3906 transistors in the photo above are installed in the
correct orientation on a v2.2 PCB with incorrect silkscreen.
1. Install the three 2N9306 transistors next
to the display, with the flat side facing
away from the top edge of the PCB.
Q1, Q2, Q3
2. Install the two 2N3904 transistors next to
the large IC, orienting them as marked on
the silkscreen.
Q4, Q5
