To your question #1: level shifting.
To answer all of your questions in exquisite detail, and show dozens of 723 circuit configurations optimizing different parameters, please look for the book shown below. Chapter 3 discusses the 723 in detail.

 

hi g,
Will work through your queries.
Attached some 723 information for your technical database, a little bedtime reading.
E

 

5...Last one, Am I correct in saying, there are two ouput conditions for a LM723, a high and a low, 1.5v to 7v and 7v to 30v.
For the lower v. range adjusting the Vref to ground is preferred, and the higher v range, adjusting inverting pin 4 to ground.

Don't see a reason for a particular preference.
The output range depends upon the configuration.
The 1.5V to 7V and 7V to 30V are two common configurations shown in application notes, but are not the only ones.
As my circuit in post #13 shows, it can be configured for the output to go from 2V to its maximum, or in post #17, configured for the output to go from zero to its maximum as determined by the input voltage.

 

To your question #1: level shifting.
To answer all of your questions in exquisite detail, and show dozens of 723 circuit configurations optimizing different parameters, please look for the book shown below. Chapter 3 discusses the 723 in detail.

View attachment 365001

Thanks for the tip, just looking at it now, there is a lot in there very detailed.

 

Thanks for the tip, just looking at it now, there is a lot in there very detailed.

Ok Gentlemen, re-group,...... I did'nt expect such a downpour of help and pdf's , I'm viewing this on a Desktop, I find lying horizontal and looking at such material on a tablet less pressure on my small brain.

I'm not expecting anybody to rush to answer my questions, I'm delighted to receive any help at all. Thank you.

 

Take your time to digest the material.
We're in no hurry.

 

Hello,

The LM723 has a separate chapter in this book:
https://bitsavers.org/components/fa...d_Voltage_Regulator_Applications_Handbook.pdf
Look at chapter 8.

Bertus

 

1...The 5.1v zener diode at pin 10, what is it's function? (previous opamp power supplies I've made require a resistor here to keep the current output of opamp within tolerance)
2...Resistor 306 1k, I see this a lot in Darlington pairs, is it not just increasing LM723 output load.

1. Zener diode shifts out voltage of LM723 in the middle of its dynamic range.
2. Resistor in Darlington pair shunts current leakage of first transistor and, also, increases its β.

 

1. Zener diode shifts out voltage of LM723 in the middle of its dynamic range.
2. Resistor in Darlington pair shunts current leakage of first transistor and, also, increases its β.

Thank you Danko, didn't know this, this whole conversation has been very informative