How come a charge pump works without a reservoir capacitor?
If you look carefully, you will see that C1 doesn't get discharged in the second circuit.  After the first positive pulse, it gets charged up, then mostly stays that way.  Since the voltage on C1 is then roughly constant, you see the same square wave at Out as you do on the emitters, except that it is offset by the voltage on C1.  Note that Out varies from about 0 to negative.  This is the same signal you would see on the right side of C1 in the first circuit.  The addition of D2 and C2 take the 0 to negative pulses and make a flat negative.  You can think of D2 and C2 as being a negative peak detector.

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