[0-30V Stabilized Power Supply]

With 27V on the output opamp then the max output of the project will be only about 21V, not 30V.
You would have the same 21V max output if you used a 21V transformer. Then only a single 2N3055 output transistor is needed and the driver transistor will be cooler.

Why not use the newer 44V opamps and a -1.3V negative supply instead so that the output can be 30V?

I'am from Bulgaria and i can't find the newer opamps. I need to find some other solution.....

[0-30V Stabilized Power Supply]

I found some interestin solution about original sheme here http://www.electronics-lab.com/projects/power/001/index.html

Received the following email from Ivan on 02/2010:

Ok. I bulid your project about a day ago. Mounted all the parts on the pcb and then concluded that there is some serious problems in this schematics. First, 2N3055 will overheat, so you have to connect two of them in parallel with emitter resistors 0.1ohm/5w. Second, maximal voltage between '+' and '-' of TL081 is 36VDC.If you connect them as it is shown in this circuit diagram that voltage will be about 45VDC, so they will burn down immediately. To fix this problem you have to reconnect all pins number 7 of U1, U2 and U3, emitter of Q3 and 'upper' end of R19 to out of an 7809 with 18V zener diode between 'common' pin and '-' of 3300uF cap, and input of 7809 connect to '+' of the same cap. Now, on pin number 7 and mentioned parts you'll have 27VDC, and total voltage will be 32.6VDC. Third, instead of using 3300uF, use 4700 or 6800uF/63VDC to reduce the ripple on higher currents (2-3A). The rest of the circuit is perfect. I like it cause it is so inexpensive and easy to make with those simple reconstructions i mentioned.

What think about this???