Self accelerating reed switch magnet spinner.

[TinselKoala]

@MH: It looks like the "power booster" circuit just allows the op-amp to switch the output transistors, which allow more current to flow through the load. Since our present design uses the op-amp to switch a power mosfet I don't think the power booster applies. But the idea of using a half-bridge, grounding the motor load thru the bottom transistor, instead of letting it "float" when off,  might be useful.

[picowatt]

Regarding high side current sensing:

http://www.analog.com/library/analogdialogue/archives/42-01/high_side_current_sensing.pdf

Something like this,

http://www.analog.com/static/imported-files/circuit_notes/CN0116.pdf

driving an active integrator with low drift and high DC precision (instead of just a passive RC).

PW

[e2matrix]

Yes, that's a great classic text all right, thanks for finding it. I found the Sams classic "Op Amp Cookbook" by Walter Jung in the used bookstore a few weeks ago and of course I scraped together my lunch money to buy it.

All op amps are not created equal. Many really do need the bipolar power supply to do their best work (like your analog power computer). Many can be used in single-supply mode as we have been doing. Some are more better for audio work, some are best for comparator applications, some are general purpose, some require dealing with more input and output options rather than just the two ins and one out of the opamps in the TL082 chip. Apparently I once again "aced" accidentally by choosing the TL082 for this application because of the very high impedance JFET input stage and the fast slew rate, and the fact that it works well on the single supply mode. And ease of use, low cost, and easy availability.

Here's something I found just a couple days ago, which made me very excited. This is another "classic" from a bygone era. The chips it talks about are still available, and many of them exist now in advanced versions that use very low power and are very sensitive. There are many many useful circuits and concepts covered in the TTL Cookbook.

ftp://apollo.ssl.berkeley.edu/pub/cinema/04.%20Science/TTL%20Cookbook_0672210355.pdf

It's a 12 MB pdf, an excellent scan, all 340 pages, clear diagrams and even the photos aren't too completely black.

ETA: I just checked EBay for sellers of TL082CN .... if you are willing to wait two weeks for a shipment from Thailand, you can get 10 for $2.79, free shipping. Or.... 50 for $9.99 from the same seller in Bangkok.
Twenty cents apiece! Delivered to your door! How can this even be possible at all?

This guy http://www.thaishine.com/servlet/the-939/10-x-TL082-TL082CN/Detail     has them 10 for $4.83 which includes shipping.   I've bought a lot of things from him and he is very fast to ship and very nice to deal with.   He sells a lot on eBay also but not sure if he has that item up on eBay.   His own web site prices are a little less than his eBay prices too. 

[TinselKoala]

Ah, yes, I got my BC337s from him, along with a couple of other items, from his EBay store. I think I'll place another order.... you are right, the prices on his website are cheaper, I could have gotten 100 transistors for about the same as I paid for 50 on the EBay store.
Shipping from Colorado, no charge, is a real plus for those of us in the USA.

[TinselKoala]

Regarding high side current sensing:

http://www.analog.com/library/analogdialogue/archives/42-01/high_side_current_sensing.pdf

Something like this,

http://www.analog.com/static/imported-files/circuit_notes/CN0116.pdf

driving an active integrator with low drift and high DC precision (instead of just a passive RC).

PW

Nice advice, added to the MH analog computer idea.

Where you been? We had a bit of fun there a little while ago with LMM, and missed your participation. I hope you watched my "highlights" of the demonstrations.