While mechanically they might seem similar, a driver is different from a pickup...they are not interchangeable. Pickups as stated are far more likely to be 8K or 8,000 ohms than anything like 8 ohms.
The design for a basic sustainer is quite clear...0.2 ohms wound to 8ohms with a thin profile. There are mods to the Fetzer/ruby circuit that make it more stable, that was not my suggestiong, but any number of non-loading (buffered or preamped) small amplifier circuits (typically LM386 based) will work. The secret is in the driver IMHO...
here's the shorter tutorial...http://projectguitar.ibforums.com/index.php?showtopic=16984
Here's a pictorial of actually winding a driver, this is built onot a pickup, but the procedure is identical for this desing...I don't see where the mystery is...http://projectguitar.ibforums.com/index.php?showtopic=24211
You do not need excessive power, more power generally causes more problems. The specs for a driver that will work are based on a many tests and verified by many, many people who have successfully replicated the design. There are all kinds of inductance and resonat issues behind why it work with these specs...but 0.5mm wire is so far out of the ballpark, it makes no sense. Also, 150 turns of 0.2mm usually gets you to about 8 ohms...so something seems wrong there as well.
The other issue that people often neglect is the potting...it will not work properly if the coil is not potted solid with glue...this is not a pickup!
Also...on LM386 circuits, I have consistently suggested a 100uF output capacitor to bias the circuit with these drivers to get a more even response and better high string response to it.
The Sustainer thread itself was an open thread for a lot of ideas and exploration...it is hardly fair to suggest the project did not have many successes from me and others in it, but it is not the thread on the design, it is the thread from which this and other designs emerged.
My design does work, is fully verified and duplicated over many years and extremely well publicized. What happens though is that people do not find the basic tutorials or follow the instructions given, make naive judgments or fail to understand what is required from the device and the requirements on it...IMHO.
I'm happy to attempt to answer questions if the tutorials are not clear...but if results are not forthcoming, blaming the design is not going to cut it because so many have been successfully made with the correct procedures and specs with complete success.
It's like saying that a stompbox design doesn't work because you thought it would be ok to use any 8pin chip or transistor that "looked" like the one specified, but had completely different pin outs or functions...or decided that glue would be a better option than solder to make it up...it really is nonsense. 0.2mm wire is quite specific enough, this will yield a driver that is efficient enough at the frequencies of the guitar and the power from a small battery power amp and not cause all kinds of EMI problems if built right (potting, care with winding, etc).
I've read most patents and discussed them over the years....for a basic working DIY sustainer, I'd not get to caught up in them. My design is quite different from the commercial versions in many ways anyway. The standard basic driver has been wound onto strat and even half HB pickups with complete success, added to passive strat pickups, or built as stand alone designs by myself and many others. Different pole pieces or a single blade has little effect on the performance of the device.
I spent a year on Hex sustainers (six separate drivers)...there are significant problems and hurdles...it really is not necessary. One thing to consider with such designs, how would you isolate one pole from another? Magnets that close to gether will be attracted to each other and therefore effectively linked. Your coil/s are also electromagnets working on this static field...how will you separate the influence of one on another. In the end, they tend to at least work as one.
This is of course only a necessary solution if there is indeed a problem. The fact is you can get a pretty ggod response from a DIY device or a commercial version without going to such extremes.