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12 Volt Regulated Supply

I was looking at a 12 volt regulated power supply at Dick Smith Electronics cat. number M9935 @

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for a regen radio I'm planning on building
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1-12af6.htm) but the AU$24 is a bit too high for my liking. I was thinking of using a center tapped transformer, 6.3-0-6.3V @ 500mA, in series with a 1.3 watt zener diode, I need help with obtaining 12.6 volts from a center tapped transformer, I never had to do it before. I thought that the two positive primary leads were connected, I don't want to blow the transformer if this isn't the case.

Any help appreciated,

Thanks Dave

Transformer is M2853, and zener diode is Z3543 @

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Reply to
Dave.H
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How would I install the zener diode? I thought they were used in series with the voltage source much like a rectifier diode, but I just read that they're used in parallel to the source. Excuse the dumb question, I've only ever had experience with rectifier diodes like the

1N4007.

Thanks Dave

Reply to
Dave.H

There were several power supply designs offered in response to your post on a voltage doubler. The same principles apply to your 12 VDC circuit. It would be good for you to become familiar with LTspice where you can try different configurations and do experiments without blowing something up or hurting yourself.

For the components you have, you will need a full wave bridge made from four 1N400x diodes, a capacitor of about 1000 uF 25 VDC, and a resistor that will drop about 5 volts at the current you need to draw, plus the zener current. With a 1.3 watt 12 V zener, its maximum current is about 100 mA, so the maximum current draw for your supply should be about that much.

Paul

Reply to
Paul E. Schoen 

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For starters: (View in courier)

The way to get 12V out of the transformer is to ignore the center tap
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Reply to
John Fields

I like that 7812 idea. The tube (12AF6) draws 150 mA, then there's the current draw of the 12 volt B+, a zener won't handle all that. A

5600 MFD 40 volt capacitor is AU$7.30, I don't like paying that for low quality Asian capacitors, so I'm paralleling 3 2200 MFD 25 volt caps in series to give a total 6600 MFD. Each of these caps cost $0.97

Dave

Reply to
Dave.H 

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You can\'t "parallel caps in series".


According to the tube specs the plate current will be about 1mA, so
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Reply to
John Fields 

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Oops...


         Idt     0.150A * 0.01s
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Reply to
John Fields

Oops. Didn't mean to say that that they were in series. I'm only paralleling them. I already have one 2200 uF 50 volt cap I'll use.

Reply to
Dave.H

How about $7, delivered to your door:

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Dave.

Reply to
David L. Jones

Simply brilliant and only $7 AD. w/postage.

I may get one just to see what is inside.

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