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Projects, Designs, and Technical Stuff / Re: LED optics design
« Last post by Siwastaja on Today at 05:15:44 PM »
Thanks,

kosine, looks interesting, although I suspect that the optical efficiency is quite poor (similar to using black plastic lens hood) but need to test this out.

Swemarv:
Was considering that LED, but it's not for new designs. This is not a one-off project, so can't use it.

Re changing the LED:
I have found only about 3-4 suitable LEDs. I need a combination of high efficiency, high power, low price and fast rise/fall times, so basically there are not so many to choose from. Osram has some of the best. In any case, the options seem to be 90 deg or 150 deg, nothing else on the market satisfying power and price specs.

Re "sharp cutout"
The requirements here are quite flexible. I'm perfectly happy if I have 50% light output at the edges, and 30% at the far corners, compared to the middle. So similar to the soft cutout of most off-the-shelf 90 degree LED radiation pattern, but just squeezed to 40 deg in one of the axis, is OK. I'm going to use a secondary black plastic lens hood to absorb stray light anyway. I just don't want to waste 50% of the LED power in this hood, so some pattern shaping is needed.


But price is important, this is going to be manufactured in masses, and I know that it costs about $2000 NRE + about $0.10 each to injection mold these lenses - so I can't buy off-the-shelf $2 lenses with 2000% markup.
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Repair / Re: two humming audio amps mystery
« Last post by Armadillo on Today at 05:14:54 PM »
If you mean to say that he took an RCA cable, shorted one end of it, and hooked the other end up to the subwoofer and it hums -- then yes,


Yes, your highlighting points out that this test is not helpful (in this case);

For one, it is certainly helpful to you to correct your own mistakes of what you have not read and in spite failed to understand and appreciate.
It is certainly not helpful if you don't bother to read, and we need to remind you and back tracks what have been said and done.
It is obvious to me that you are grasping with the subject of the ground loop noise that you don't quite understand and needs to be pointed out of the 2 types we are dealing with.

The test conducted that you think is not helpful, was to ascertain that it is from the type 2 noise.
You have no means and methods to differentiate the two and less understand the types per se other than judging others to elevate yourself.   :box:
Cheers!   ;D
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What's inside an implantable  Medtronics Itrel 3 Neurostimulator designed for Neuropathic pain reduction.
Dave tears into the ultrasonically welded titanium case.


Dave, nice tear down. Back in the '90s I worked for a pacemaker company and for pacemakers, the 2 clam shells are welded together in a helium environment with a laser welder, therefore the interior is sealed after welding with high helium content that also keeps things dry inside. The helium allowed the welding to occur without nitrogen yellowing of the titanium case, which, we ran tests in a highly nitrogen environment and discovered the yellowing effect after welding.

An interesting fact about titanium welding is that the "dust" that accumulates from the welding is very volatile when exposed to atmosphere (21% oxygen, 78% nitrogen, 1% other). The filters used in the welding cabinet would have to be pulled and immediately placed into a zip lock bag that had a shot of helium injected into it. The technician performing this maintenance would have to quickly carry the filters outside to the parking lot and pierce the bag in an open area and allow it to start fizzling and burning and would beat on it until satisfied that all of the dust had been exposed and the reaction was complete (had stopped burning) before tossing the filters into the dumpster.

We always watched this spectacle every month on the scheduled day to insure that the pyrogenic reaction was done before the filters were thrown in the dumpster.

Also, you are correct about the differences between this device and the pacemaker. The pacemaker hybrid is much more complex. In our hybrid assembly facility, which was a class 10,000 clean room, we manufactured everything onsite except for the ASICS. We received the wafers, however and sawed the chips off of the wafers and placed them into special containers that we developed. This was done outside of the assembly area in a special room. The saw had air bearings and turned at very high RPMs. This machine was very specialized and very precise.

The substrates were made onsite from green tape. These substrate boards had 9 layers and once the shape was cut from a "cookie cutter" from the pliable green tape form, then had all of the vias punched from a special machine that was developed specifically for this process. The vias were filled with a gold paste under very high pressures and the traces were done in a similar manner. Once all operations were done, the substrates would get baked in a very long oven which had a conveyor made from a chain like construction made from stainless steel.

I could go on and on about the different processes. My job was to study new machines that was purchased for specific operations/processes and to custom modify them to do specifically what we needed it to do. We also created and designed some of our machines, such as the laser welder mentioned above, when we could not find what we wanted on the market. As our processes matured, to revisit the machine and either modify to hone in on the design or make recommendations about future machine purchases. I had a blast with that dream job.

It all ended when the parent company decided to sell the pacemaker division to a rival company who only wanted our pacemaker leads, which were at the time, the best in the world. After the new company plundered that technology, all 1500 employees were laid off. This was in 1999, I started with the company in 1989, and was laid off on my 10th anniversary with the company.
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Beginners / Re: Help with desoldering
« Last post by helius on Today at 05:09:52 PM »
In situations where you only have 2 pins and they are pretty close together, you can apply heat to both at once and the pins will drop out. You can add some solder to bridge the pins together and hold the iron on them until the header pins fall out (if you want to encourage them out, remember they will be very hot so use tweezers or needle nose pliers not your hand!)
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... LC oscillator controlled via a relay from an Arduino which will measure the frequency as per http://www.qsl.net/wm5z/cq199301b.pdf

Thanks! Saved for my reading list.
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you could email  to our after sales

...a webpage with a link to the software, plus a changelog would be a good, professional idea, no?
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Well looks like that might be the case. After charging overnight, I tried to discharge it with an RC Lipo pack charger/discharger, and it cut out pretty quick. Did it again with a voltmeter on the output, and it fell to about 14.5 V before the BMC cut off. Rats - need a new pack :( Strange that both behaved in such a similar manner.

Thanks for the pointer. I forgot that BMCs can cut off even if a single cell falls below threshold.
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General Chat / Re: Nintendo Medical
« Last post by tooki on Today at 05:04:02 PM »
Oh. It’s got nothing to do with being a twitter member or not. The guy seems to have changed that post to private after I linked to it (and lots of media embedded it and referenced it) — I just wanted to link to the source and not a clickbait website, but oh well.

Here’s an article: http://www.distractify.com/trending/2017/09/21/lSlMc/med-device-gameboy
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Beginners / Re: Correct punchdown tool for this connector?
« Last post by Nusa on Today at 04:56:05 PM »
Yes, those look like MTA connectors of some brand, for which manual punch tools exist.

For good results, you need to use the stranded wire size the connector was designed for.
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Test Equipment / Re: Old Fluke Multimeters
« Last post by helius on Today at 04:54:15 PM »
hello, anybody have a picture of the 300v version of the 8060a? i never have seen any. unless the exterior labels be the same in both 1000v and 300v (i doubt it), if yes how to know which is which?

In 1990, the "CAT standards" (Measurement Categories per IEC 61010-1) for meters were released. The Fluke 8060A can only withstand 300V on its resistance ranges, so it can only meet CAT I 300V. To qualify for a "CAT I" label, the voltage ranges were reduced to 300V for both DC and AC. Otherwise, I don't think the meter was changed: it is no safer than the unmodified 8060A.

It can be recognized by two differences from the normal model: the presence of "CAT I" below and to the right of the red jack, and the highest voltage range is marked "300V \$ \simeq \$ " instead of the normal "1000V DC / 750V AC". In addition, the maximal voltage limits printed underneath the jacks are lower (300V MAX from common to earth instead of 500V, and 300V \$ \simeq \$ from red to common instead of 1000V DC / 750V AC MAX).

Here's a picture: https://cache.osta.ee/iv2/auctions/1_9_30853067.jpg
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