[0-30 Vdc Stabilized Power Supply]

Ok just finish building the power supply, I had to make a new PCB but this project has taught me a lot. so I didnt mind.
I use the TL081 but use a LM7809 to drop the voltage down, use a 30V 3Amp transformer and the Power supply outputs 25 volts which isnt bad :D Thanks for all the inputs into this thread it help to better my design :) Here's a couple of photos.



[img width=680 height=510]

[img width=680 height=510]

No room left for the amp meter to be install inside the case, so stuck it on the side  :D

[0-30 Vdc Stabilized Power Supply]

Thank you for the quick reponse, I will remake the PCB and start again. I will use the upgraded parts on the rest circuit describe by one of your early post. 0-20V will get me out trouble for now, I will upgrade transformer to a 30V 3A later on. Time to go to the local electronic store by more parts lol

[0-30 Vdc Stabilized Power Supply]

Ok Im trying to fix my project using the following info.

    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.

I was wonder if I insert the LM7809 into the circuit properly, I dont really understand words sometimes, and if i got it wrong I was wondering you could supply the correct schematic.  I cant buy any other IC listed in fixes expect a MC34072DG and know it wrong IC but it all I got :/