What is the circuit formation in this electric blackbox?
Work in progress ...

Table 1. Information supplied in table format.

          a          b           c          d          e
        k off -------------    k on -------------------------
        DF disc.   DF conn.               CA conn.   ED conn.
        --------   --------    --------   --------   --------
U_AB    3 V *                                        2 V
U_AF    0 V        1.5 V
U_BD                                      0 V
U_BF    3 V *
U_CD               0 V
U_DE    0 V                               0 V
U_DF                           1.5 V **
U_EF                           1.5 V **



and ** require that sign is not being reported.








simulate this circuit &ndash; Schematic created using CircuitLab

Figure 1. Our kit of parts and meter readings.

Things we know:


3 V terminal voltage is from the battery with or without one or more series resistors and the forward biased diode (provided it isn't passing current).
2 V must be tapped off on the 3 &Omega; potential divider.
1.5 V must be a tapped off from a two resistor potential divider.