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Quote from: janoc on November 21, 2018, 02:52:34 pmI am fairly sure that the quality of their "100% online" education matches the quality of their advertising. That's what you get with "100% online" - no labs so nobody to show you how a scope probe works ...They give you a stupid pictoral diagram and expect you to practice with a stick.
I am fairly sure that the quality of their "100% online" education matches the quality of their advertising. That's what you get with "100% online" - no labs so nobody to show you how a scope probe works ...
GOLD!
ok not electronic releadet but a translate fail:from a Ebay Seller.Run for my life? Does the sell so much crap....
Being a distributor just means they sell stuff, not necessarily that they know about the things they're selling...
Check out 8:30 to 9:00
Talking about cringeworthy nuclear facilities, I have a story to share.My professor was working on a consulting job where he needed a personal favor from me testing some power devices for a generator of a nuclear plant which I will not disclose.Through the project, I was given more information on the plant, and I am really glad that I don't live close it.The nuclear plant has two diesel generators per nuclear generator in case there's a total loss of grid power and a nuclear generator failure as well as a local grid failure that prevents energy from the grid, the reactor itself or another reactor in the plant, to feed power to the cooling system.The plant uses Fukushima design, and we all know what happens if it loses all cooling power.Each diesel generator runs on a non-inverter design (it was designed in the 70s), and it has an exciting field coil driven by an AC-DC converter that stabilizes output voltage (AVC/AGC).The exciting coil driver is based on SCRs, fed directly from the output of the generator.Well, here's the problem. On safety drills, they discovered each of their generators fails every around 100 hours of operation, and they tasked us to find out why.Here's the fun part after we inspected the driver:1. There's absolutely no decoupling on ICs. Analog chips and discrete logic chips are powered without local decoupling caps, and there're no decoupling planes. Two layer boards, that's it.2. There's no di/dt and dv/dt protection on gate drivers. The units started to fail in the new century as old diodes ran out, and new diodes are faster, thus creating more di/dt. They tried to source old-design diodes from an Indian company making so called 100% clone of old devices, but apparently the new clones are way faster than the old ones.3. They literally used LM723 as opamps. That's right, they never had a single real opamp in their circuit.4. Their over voltage protection uses a selenium rectifier as zener stack, and the connection is through a 4m roundtrip cable. That offers zero protection on transients.5. Their driver is based on SCRs, and common sense tells me if you use a majority carrier device, you use transient absorbers. No, the original designer didn't give a heck about it. No snubbers, no TVS, no nothing.6. And the best part. The system is so vulnerable that any external EMI knocks it out. We were not even able to get a scope in the control chassis without disturbing it. We ended up having to bring in a battery powered, EMI optimized, high speed data logger to capture waveforms.And the bonus point, it is still running, though the authority has given them a specified deadline to fix everything.
I always find it difficult to install through-hole components on surface-mount pads.