Well, I have revised my design, based on the help of another electronics enthusiast and the figures and notes on the LM723 datasheet, but I've still got one problem that I'm stumped on.
I've made the following changes from my first design:
Replaced 2n222 with higher rated transistor (BD135)
Replaced 2n3055 with higher rated transistors (2N3771)
With the higher rated Q1, and the higher Gain of the two base transistors, this should eliminate the problem I had with 2n2222 going pop.
I have moved the potentiometer to where it should be (According to the LM723 datasheet) and added R1 and R2 resistors in (Those values are also what the datasheet recommends for variable power supply's in the 12v range)
Replaced the Freq comp capacitor with 470pF and added a 100uF Capacitor for improved dc output?
So with this new circuit I would be happy with a range between 4v and 12v but Instead I cant get over 7v, no matter what resistor values I try. I'm really stuck here, Anybody with any input on this would be very much appreciated.
Cheers,
Dan.
*Note* Fixed this problem, Am using a 15k resistor between Pin 4 and Vout, and 12k Resistor between Pin 4 and negative, Found I am now getting 1.5V-15V using a 1k Potentiometer. I removed these resistors as per LM723 instructions when adding a variable adjustment to there voltage regulator diagram, turned out to be a big waste of time