Issacsutt

modified 8 years ago

High Precision Voltage Regulator

313

04:01:06

Using a good current source with a zener diode can help improve stability tremendously, (for every circuit, about 13mA seems pretty good with the default settings at 5.1v).  Because perfect current sources don't exist like they do in EC, if your using transistors; biasing a PNP with a zener diode at: Vcc-1.5v, works really well and keeps it stable with just a few components. There's no load on this circuit yet, but I'll make some updates later, and see how it does with a load using just 1 or 2 more transistors as a buffer...  from there, I'll see if it still needs more improvements.

published 8 years ago

hurz

8 years ago

Right, this is actually a current source with a single PNP while the NPN can be replaced by a diode. Two times 0.7V is the reference while one time 0.7V across 50 Ohm give the current. Close to 13.6mA generates the perfect zener voltage within everycircuit. Simplified to standard current source http://everycircuit.com/circuit/5102948685447168

Issacsutt

8 years ago

I tested it with the diode instead of the transistor at first, and thought it wasn't doing as well, but your example looks good. I updated it with a 1.5v zener, and it actually does pretty well, a little better even.

Issacsutt

8 years ago

Check this out, can drive a 40 Ohm load without dropping below 5v.... not too bad: http://everycircuit.com/circuit/6128446483988480

Issacsutt

8 years ago

And, here's a nice little 100mA current limiter I made using this voltage regulator: http://everycircuit.com/circuit/6581051211382784

hurz

8 years ago

Again, this is a standard current source applied to a zener which give a good voltage reference. However, calling it "high precision regulator" is by far too much! Its not high precision and its also not a regulator! Its a good voltage controller, nothing else.

Issacsutt

8 years ago

How is it not a voltage regulator!?!?

hurz

8 years ago

You know the difference about controlling and regulating?

Issacsutt

8 years ago

No, what do you mean by controller? All I know is this circuit can take a wide range of input voltages and maintain a steady output voltage for loads on the output regardless of the input/source as long as it at least like 6 or 7v; that is known as regulating to me.

hurz

8 years ago

E.g. close your eyes, you as driver of a car controlling the steering wheel to change the car direction. As long your eyes are closed you just control, you have no idea were you are and going to, but you know were the steering wheel position is to go straight, left and right. Open your eyes and get some feedback were your are controlling to, we can call it regulating. So a combination of controlling and feedback is regulating, while without any feedback its called controlling.

zorgrian

8 years ago

Suggestion: add a tag to each circuit in EC for working/ not working. This way when you search for circuits to do something useful, you can find circuits that meet the functional specification.

zorgrian

8 years ago

@hurz, that is brilliant! Excellent description of control feedback and regulation.

hurz

8 years ago

Nice to hear you like this picture of analogie.

Issacsutt

8 years ago

I understand, you didn't have to get that detailed. This has me curious though; what about just a simple series resistor with a zener diode, coupled to a transistor for a load... that's a very basic and common circuit know as a voltage regulator and doesn't have any feedback, so then why is it known as a voltage regulator?

hurz

8 years ago

You know it as voltage regulator. I call it emitter follower or voltage follower.

Issacsutt

8 years ago

True

hurz

7 years ago

Looks like I have to go much more in detail, be happy somebody does that for you. You sound respectless.

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