Dividing and Multiplying Voltages

It is fundmentally insane not to do this digitally.

You're on the right track for the addition and subtraction. As Bruce mentioned Analog Devices and Burr Brown (and possible ON semiconductor) should all have analog multipliers. The multiplier data sheets have information on doing analog division by putting the multiplier in the feedback loop of an op-amp.

-- snip --

With emphasis on the "fun"!

Unless you're going to be operating in the MHz region, in which case you are going to have some pretty severe challenges, particularly in implementing the divide.

I read in sci.electronics.design that snipped-for-privacy@gmail.com wrote (in ) about 'Dividing and Multiplying Voltages', on Wed, 15 Dec 2004:

Posting twice with different Subject lines won't win you friends.

Is this homework? We don't do homework, but you may get a few clues.

Yes, that's OK. Watch the offsets if the voltages are d.c..

I don't see any multiplying. For dividing, you can either use a log- subtract-antilog technique or a voltage- or current-controlled amplifier. National Semiconductor application notes on the web may well help.

Nice to see someone is still in the analog world. It's becoming a rare thing nowadays.

The analog multiplier/divider field was very alive in the 'analog computer' days, years ago. There were several schemes, none of them thoroughly easy to implement. Two were the quarter square and pulse width multipliers, try googling.

I presume that nice function blocks would still be available - Analog Devices, Burr Brown? These are a lot easier, as you get something with guaranteed specs, without having to mess around. You do pay for precision, however.

You mention that digital is not acceptable, however being practical, if you take the time to set up a reasonably high res ADC and DAC through a convenient digital box - PC, DSP or other micro, then you can generate whatever functions you need, quickly, easily and repeatably, as long as your speed rquirements aren't too great. I'd be surprised if you couldn't buy some programmable an-in/an-out hardware ready-made, you can certainly easily get analog interface cards for PCs.

Hmm, what if along with the high-speed capability you need very high resolution?

It's too bad the O.P. created two threads for this t>

The use of the above parts with a little care allows one to make a high-performance analog instrument that'd be difficult to match with all or mostly digital circuitry. One would have to employ four high-performance A/D that're on the bleeding edge of industry offerings (i.e. 20+ bits and 1MHz+ speed), and don't forget the required anti-alias filters. Couple this with fast DSP circuitry for the calculations. If the resulting signal is to be used in a servo loop, as my analog circuits described above have been, one needs to minimize the digital pipeline delays, and add multiple blistering-fast D/A outputs along with the appropriate filters.

Yes, the digital approach would be fun, but a high-performance version would be an expensive undertaking compared to the analog approach, and even given today's advanced technology it might well fail to match the performance of my 15-year-old analog design.

Be advised the OP is worse than a troll and is a stupid idiot - and i am being polite. He posted on the petroleum NG that there is unlimited oil, and fruthermore that there is oil on Mars.

Yeah, well they may be more to this then meets the eye.

For me, when I was first told at 14 in school chemistry class that oil was the result of long dead animals, I didn't believe it. I still don't. There is simply way too much of the stuff around. Since basic hydrocarbons have indeed been discovered in space, its clear that we don't need "organic life" to produce them. There is two basic options either simpler oils came from *immensely* more complex organic life, or the basic hydrocarbons are the materials that more complex life was built from. I know which one makes more sense to me.

Kevin Aylward snipped-for-privacy@anasoft.co.uk

But, imho, we shouldn't withhold a good discussion from entering the archive because of the source of the original question.

I read in sci.electronics.design that Kevin Aylward wrote (in ) about 'Dividing and Multiplying Voltages', on Thu, 16 Dec 2004:

There is a problem with life developing from hydrocarbons. They don't contain any oxygen, and all the known molecules essential for life do contain it. It really isn't easy to partially oxidize hydrocarbons in the way needed to form, for example, sugars.

The 80 barrels of oil recovered from a depth between 5km and 7km in the crystalline granite of Sweden between 1986 and 1993 wasn't much to burn, but the purpose was to show established theories of oil formation are either wrong or at least incomplete. This wasn't primordial oil exactly. Significant amounts of oil may someday be found in unexpected locations.

In article , Robert Baer wrote: [..]

He is right if that is as far as he went.

If you count all the tar sands and trapped non-recoverable oil, we will run out of air to breath before we would run out of oil. If you look only at what oil we can lay our hands on, the situation is quite different.

A few years back a fellow by the name of Dr. Gold got a bunch of funding to drill in a place where no oil should exist (except for the primordial) and as a result added a teaspoon full of oil to the worlds supply. There is very likely to be some oil on Mars. Not all of it would have been baked out when the place was formed.

In article , Rich Grise wrote: [...]

Yes but it won't work very well unless that is a very deep hole you drill. Although it is common for the bottoms of oil wells to be above 200C, rocks aren't very thermally conductive.

You may be better off not actually putting the U at the bottom but instead forcing the water to flow through the rocks.

Rich's remark misses the point of Thomas Gold's deep-drilling exercise, which was not that one can find more oil for our use deep in the earth, but to prove conclusively that the popular theories of the origin of oil are wrong or at least incomplete. Following other Thomas Gold research shows that he believes easier-to-reach oil may one day be found in unexpected places.

Yup!

I didn't mean to imply that hydrocarbons were the only ingredients.

So, we need some process to get combination of all the ingredients. Yeah, no one said that life was easy:-)

But the idea that *hugely* complex molecules spontaneously existed at the from the big bang, makes little sense to me. I'm not a chemist, but I see little alternate other then complex molecules are formed from less complex ones. How, I have no idea. I am not a chemist.

Kevin Aylward snipped-for-privacy@anasoft.co.uk

I read in sci.electronics.design that Rich Grise wrote (in ) about 'Dividing and Multiplying Voltages', on Fri, 17 Dec 2004:

You just re-invented geothermal energy. What next? The steam engine? (;-)

I read in sci.electronics.design that Kevin Aylward wrote (in ) about 'Dividing and Multiplying Voltages', on Fri, 17 Dec 2004:

Nor to me, and there is no need for such an unlikely hypothesis.

Never mind; the spontaneous synthesis of complex molecules is easy. It's happening in your friendly neighbourhood gas-cloud as I write. (;-)

What we don't know enough about yet, even to decide if it's so easy as to be almost inevitable, or almost impossibly difficult, is the spontaneous synthesis of *self-replicating* molecules. But, to me, the trend of discovery points towards the 'inevitable' end of the scale.

There's a lot of stuff written on this, try Dawkins, Dennett, Gould etc. When I'm rich enough to be irresponsible, I'm going to sponsor a prize for the simplest self- replicating molecule synthesised from scratch. The only trouble is, they might come up with a better one than DNA...

Paul Burke