That Circuit Might work, If regulation wasn't important (It will vary about 300 mV from no load to about 200 mA and it isn't very thermally stable, Diodes are commonly used as temperature sensors in IC's like Processors. After all there's a whole lot of diodes in a Processor. It is also missing a 47uF cap. No Power supply should ever be without some bypassing. The voltage will range from about 750mV @ 0 C to about - 500 550 mV @ 80 C @ 100mA current. Not a lot really considering digital electronics but more than enough to vreate problems with any linear circuitry.
Bob