Use of two power sources in voltage regulator using zener diode

Thread Starter

The Engineer

Joined Sep 3, 2014
I am currently designing a voltage regulator using a 5V zener diode.
I am wondering why some people choose to use two power sources instead of one, what would be the benefits of this ?
the circuit is being simulated on multisim.
the two attachments uploaded are as follows :-
the one with one power source is my circuit which I am looking to improve
the one with two power sources is a friends circuit, I cannot understand why they have used two power sources.

any help with this will be greatly appreciated !

also any advice on possible modifications to the circuit would be great ! I get points for testing circuit in different ways so any advice will help :)



Joined Aug 23, 2012
According to your circuit, a calculation as below:
Vout_741 = 12V - (1.4V~1.8V) = 10.2V~10.6V
Vout = Vout_741 - Vbe = (10.2V~10.6V) - 0.7V = 9.5V ~9.9V
V(-)_741 = Vout /2 = 9.5V ~9.9V = 4.75V~4.95V
So here you have the output voltage around 9.5V ~9.9V.
Is the voltage what you want?
The 2N2222A can't afford too much current, are you just care about the voltage?


Joined Mar 14, 2008
The dual supplies are needed if the op amp won't operate properly with a 5.1V input and the minus supply node going to ground (but most will).

What improvements are you looking for?
What's the maximum output load current you want to provide?
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