This circuit limits the output to +/-5.76V. The diodes are biased to only conduct when the desired limits are exceeded (with some consideration for voltage drop across the diode).
The left resistor is necessary to limit current when the diodes are conducting (clamping). Unfortunately, this makes this a less ideal power source. This is because the current-limiting resistor and the load resistance create a voltage divider at the diodes, so changes in load resistance (right resistor) affect output voltage.
