Dr Chubb's classic DCC occupancy detector, used.
From time to time we acquire these as part of system reconfiguration projects or from downsizing or estate sales. These are tested and repaired as necessary. They are compatible with our ODX4 motherboards and classic ODMB motherboards, which we also have from time to time.
The Bare Boards come from similar sources and are (as far as we can tell) genuine boards from JLC Enterprises.
We also repair DCC-ODs on a time and materials basis, they usually cost about $10 to repair (try changing the LM324 Op Amp and replacing the pot before sending them in, these are usually the problem).