12 vdc

Zeners? Why not just use resistors?

How precise must the voltages be?

Not that special Give it a try

Why not just buy an off the shelf adjustable power supply. Altronix used to make one but I haven't seen in on my local distributor's shelf for a while. You might want to check their website at

Just series in 1 watt zeners until you get a voltage you can live with.

4 or 5 zeners should produce roughly 9 volts. Just use a meter as you connect each one.

Jim Rojas

Rich wrote:

Do you live near a university? Call the Physics department there. They would be glad to have a student assist you I bet. This looks like a typical question on a physics test actually, but that was many moons ago when I took that class.

Physics? No Roland, it's a basic electronics question. Last time I took physics they didn't teach DC circuit analysis.

Just pick up an LM7809 +9VDC/1A 3-pin voltage regulator module and wire it according to the diagram on the back of the package.

If memory serves (I haven't really worked with this stuff in about a dozen years) you can adjust the output voltage by lifting the ground leg with a resistor... or a variable resistor to make it adjustable.

Or just use an LM317 -

- where it shows the transformer and bridge rectifier, substitute your battery.

Really? Were you awake the whole time? I think you missed a big part of the class. Here is the class I took where I learned DC circuit analysis (AC too for that matter). The professor was so old school he taught using the old way of electron flow from positive to negative, instead of negative to positive (he knew the difference, it was just easier to teach it the way he learned it)

1420 (PHYS 1402) General Physics II. (3-2) This is the sec>

Nope, I did very well in physics, I found it fascinating.

You didn't learn DC or AC circuit analysis in the course you quoted below because it is a PHYSICS course. Sure you may have gotten the theory of electron flow there -- but not in-depth circuit analysis...

1420 (PHYS 1402) General Physics II. (3-2) This is the second course in a two semester sequence which is a survey of the basic laws and principles of physics and includes the topics of waves, electricity and magnetism, and light. PHYS 1410 and 1420 are designed for those students whose program requires technical physics but who are not pre-engineering students or majors or minors in physics. Prerequisites: PHYS 1410; MATH 1315 with a grade of "C" or higher. MATH 1317 is recommended.

Now *this* would be a little closer:

2425 (PHYS 2426) Electricity and Magnetism. (3-3) A study of the field of electricity and magnetism for physics majors and minors. PHYS 1430, 2425 and 2435 are designed for students majoring in physics and for pre-engineering students. Credit in both Physics 1420 and Phys 2425 cannot be given. Prerequisites: Phys 1430. Corequisites: Math 2472.

But *here* is the course that would have taught any usable circuit design:

3416 Applied Electronics. (3-4) Laboratory/lecture course introducing electronic test bench methods for the construction, operation and analysis of important DC/AC circuits utilizing resistors, capacitors, diodes, BJT's, FET's, OpAmps, and analog/digital ICs. The behavior of the circuits will be modeled in SPice, Elementary semiconductor device physics and microfabrication methods will be discussed. Prerequisite: PHYS 2435.

Physics? I for one don't take physics anymore. All I do is wash some whole wheat bagels down with some prune juice in the morning and that'll conjure up an equal and opposite reaction real quick.................No Shit Folks!

OK, so which one of you Einsteins will draw the schematic? Ready, go.

Physics? I for one don't take physics anymore. All I do is wash some whole wheat bagels down with some prune juice in the morning and that'll conjure up an equal and opposite reaction real quick.................No Shit Folks!

I call:

2425 (PHYS 2426) Electricity and Magnetism. Note:

It is virtually the same class. One is for Physics majors.

I wasn't after a EE degree. So that takes us back to the beg>

microfabrication

We don't agree. That is a fucknutted idea.

Nice dodge. Graham?

See below:

Are you saying that I'm #1? Or that you need just a moment to complete the assignment?

What?