This is a picture of the laser CW receiver.  The item on the
right is the PIN photodiode, which is mounted in a PVC pipe end cap.
The board next to the photodiode assembly is the preamplifier and 800 Hz
filter.  This allows ambient light noise (e.g., 60 Hz and 120 Hz from
incandescent and/or fluorescent lamps) to be filtered out.  The
preamplifier uses one section of a TL082CP op-amp chip, while the filter
uses the other size of the TL082CP op-amp chip as an active filter.  The
next board is the audio amplifier, which is based on an LM386 op-amp
chip.  The round black object above the audio amplifier board is the
speaker.  The object to the extreme left of the image is the 12 volt
power supply.  A modular design was used to that sections could be
substituted.
The PIN photodiode used is an Osram SFH 214.