John Curl's Blowtorch preamplifier part III

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#30,424
Max Headroom said:

Yes.
Photon Induced Non-local Effects of General Anaesthetics on the Brain

Dan.
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Stunning BS!! From another of their papers prose only equaled by KBK.

As an alternative to our original dualistic approach, we present here our spin-mediated consciousness theory based on pan-protopsychism. We postulate that consciousness is intrinsically connected to quantum mechanical spin since said spin is embedded in the microscopic structure of spacetime and may be more fundamental than spacetime itself. Thus, we theorize that consciousness emerges quantum mechanically from the collective dynamics of "protopsychic" spins under the influence of spacetime dynamics. That is, spin is the "pixel" of mind.
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#30,428
chris719 said:
You don't need an oven to do SMD but if you have a large board or high density design it certainly saves time.
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I have an IMDES vapour phase machine, just large enough for for double size Eurocards.
(160 * 233.4 mm). I have bought it so I can handle large ball grid FPGAs, but I used it
up to now more for playing around to get some routine. Those FPGAs use to cost
a few grand.

It should be in the same price range as yours.

regards, Gerhard
 
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#30,429
gerhard said:
I have an IMDES vapour phase machine, just large enough for for double size Eurocards.
(160 * 233.4 mm). I have bought it so I can handle large ball grid FPGAs, but I used it
up to now more for playing around to get some routine. Those FPGAs use to cost
a few grand.

It should be in the same price range as yours.

regards, Gerhard
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I saw those. I was a little worried about the Galden vapor. It's inert and non-toxic itself, but it's PFPE (perfluoropolyether) and compounds used in the manufacturing of other PF items are not good and often present in low levels as a contaminant in the final product. PFPE is mentioned but I'm not sure there is any data. Still, we wanted a larger volume anyway so we got the conventional oven. I am not a chemist, so there may be no issue here.

https://www.epa.gov/sites/productio...rth_kansas_presentations_september_5_2018.pdf
 
#30,430
I have fitted a toaster oven with this $100 controller X-toaster | Toaster Oven Reflow Controller
we also wrapped the side of the oven with some Mcmaster Car insulating tape. It work well for our AuSn experiments. I have used it prior to taking it to work on my DIY SMD project. Currently I am working on 400 GHhz OptoASICS. Solder bonds are critical. About $150 total for oven and controller, Make sure you get an oven with ceramic heater elements
 
#30,431
Yes Bill,

I did have to pay an NRE for the solder screen.

I also got your reference to the 10,000 hour bit. That is why at the standard 3 seconds per joint, one could not live long enough to really spend 10,000 actual hours soldering. (Some include all the time involved even just thinking about it!)

I have seen wave soldered PCBs on stuff in current production! Mostly all through hole parts in audio power amplifiers from folks in the business for decades.

Having now hand soldered 50 or more of the various prototypes I may just pick up an oven myself. One issue on the most complex version of my microphones had 20% of them fail due to a solder bridge between a via and some nearby leads. (.025" lead spacing) So that wouldn't be a problem with reflow soldering. I am however changing the layout after my learning curve on how to test and repair the PCBs.

Also turns out PCB thickness is an issue.

So 60 years after building my first audio amplifier I still have a bit to learn! Who knew things change!!!

BTY I am now starting to buy some small components in full reels, just for prototyping.
 
#30,436
The important thing with the zobel is that you don't end up increasing the inductance through the RC between terminals.

The wire leading to the zobel is the inductive part of a pi filter, thus it's wire spacing and length matters, and shouldn't be changed. Are the wires longer than necessary to reach the posts? It could be intentional.
 
#30,440
gpauk said:
Science is not a belief system.
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Science is a belief system, and fortunately for us all it happens to be largely true. For example, you cannot do science without an underlying assumption that the universe is rationally explicable yet there is no a priori reason why this should be true - even Einstein was puzzled by this. There are other belief systems, which may or may not be true and may or may not conflict with science. Science gets in a mess when it claims to be the only true belief system (which is clearly a 'faith' statement), or if it claims that it is not a belief system.
 
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