Electrical Engineering V3 - Developers

My friend bought an[URL="http://www.staples.ca/en/Tensor-LED-Double-Reach-Premium-Desk-Lamp/product_1574838_2-CA_1_20001"] LED desk lamp[/URL] and quickly discovered that whenever he turned it on, his PC would shut down. He solved it by moving the PC power cord and lamp cord farther away from each other. Seems kinda pathetic for a $75 lamp to to do that. Also whenever my mini fridge kicks in it resets my USB hub which includes my keyboard, mouse, phone, PS3 controller and external hard drive. It's happened a few times while playing Rocket League and the controller doesn't recover and it's possibly the most frustrating thing to happen during a match. So far I've put a large metal plate behind the fridge and a metal cage around the hub (both grounded) and it didn't do anything.

[QUOTE=No_Excuses;49136010]My friend bought an[URL="http://www.staples.ca/en/Tensor-LED-Double-Reach-Premium-Desk-Lamp/product_1574838_2-CA_1_20001"] LED desk lamp[/URL] and quickly discovered that whenever he turned it on, his PC would shut down. He solved it by moving the PC power cord and lamp cord farther away from each other. Seems kinda pathetic for a $75 lamp to to do that. Also whenever my mini fridge kicks in it resets my USB hub which includes my keyboard, mouse, phone, PS3 controller and external hard drive. It's happened a few times while playing Rocket League and the controller doesn't recover and it's possibly the most frustrating thing to happen during a match. So far I've put a large metal plate behind the fridge and a metal cage around the hub (both grounded) and it didn't do anything.[/QUOTE] The fridge is probably kicking power pack into the line when it turns on. However I would think that any decent PSU would have no trouble with that, and if it did it would affect the whole system as opposed to one specific peripheral. The usb hub probably just has some really poor/no shielding against EMI.

[QUOTE=papkee;49136860]The fridge is probably kicking power pack into the line when it turns on. However I would think that any decent PSU would have no trouble with that, and if it did it would affect the whole system as opposed to one specific peripheral. The usb hub probably just has some really poor/no shielding against EMI.[/QUOTE] Most don't, tons of people always bitch when they buy $5 usb hubs to run usb power into their synthesizer collections. They bitch because "hey guys why am i getting this weird noise in my synths output" dude

[QUOTE=papkee;49136860]The fridge is probably kicking power pack into the line when it turns on. However I would think that any decent PSU would have no trouble with that, and if it did it would affect the whole system as opposed to one specific peripheral. The usb hub probably just has some really poor/no shielding against EMI.[/QUOTE] To add to this, the fridge and my PC are on the same outlet but everything sensitive including the hubs supply is connected to one of these [URL="http://www.upsforless.com/browseproducts/ZeroSurge-15Amp-Power-Filter-Surge-Suppressor-NEW-(2R15W).html"]standalone surge protectors[/URL] which is full of additional emi filtering. In fact when the fridge kicks in theres an audible pop from a pair of powered speakers upstairs maybe 15' away.

Surge protectors are more of a scam than actually useful, most modern power supplies contain enough surge protection as it is, the only case I would suggest one is if you have regular lightning strikes on the power line, one thing I would check is that you have a good low impedance earth connection otherwise the EMI / RFI filtering would be severely degraded.

[QUOTE=Chryseus;49139302]Surge protectors are more of a scam than actually useful, most modern power supplies contain enough surge protection as it is, the only case I would suggest one is if you have regular lightning strikes on the power line, one thing I would check is that you have a good low impedance earth connection otherwise the EMI / RFI filtering would be severely degraded.[/QUOTE] Don't worry I didn't pay any money for it but I figured it can't hurt anything to use it.

I just fixed a brushed motor that wouldn't turn anymore. I applied 3A to it, delivering a total of 10W to it, until it got to a temperature of something like 80°C on the outside. It suddenly started turning again, so I quickly cut the power. After letting it cool down, I hooked it up again, and it turned just like a new motor. It's amazing how dicking around spared me the wait for a new motor!

[QUOTE=Zero-Point;49130492]That's okay, I was fixing a spot-pinner (like a spot-welder, but it welds in special pins), found out that the switch leads weren't good so I replaced them. Still doesn't work, despite already testing everything else: Mercury relay (yup, one of those) is good, coil resistance is good and the switching part works because turning it causes the welder to activate, whether the trigger is pressed or not. So either I'm going to have to figure out what's really going on with that damn relay, or I'm going to have to ask the bosses if they'd rather replace it with a solid-state relay instead, but since that would cost money their answer is likely "Hell no". :disgust:[/QUOTE] Got it fixed, had to disconnect everything and rewire it according to the schematic (fuck wiring/connection diagrams, they are terrible), and according to my foreman it works even better than it did before, probably because they had it wired for 190V instead of 220V initially.

Finally! My first modular Tek scope! :dance: [IMG]http://i11.photobucket.com/albums/a166/ballsandy/CGS_1153.jpg[/IMG] [IMG]http://i11.photobucket.com/albums/a166/ballsandy/CGS_1152.jpg[/IMG] The power cable is totally fucked so I have to replace that before I can test it but look at those sexy plugins that it came with. 80 [IMG]http://i11.photobucket.com/albums/a166/ballsandy/CGS_1154.jpg[/IMG] [IMG]http://i11.photobucket.com/albums/a166/ballsandy/CGS_1155.jpg[/IMG] Fucking 50mhz in 1968. This must of been 'spensive. Good thing it only cost me $30.

I still don't have a scope.

are modular scopes like modular synths? hey yeah I'll just buy this one module maybe a few fx [t]http://www.sequencer.de/blog/wp-content/uploads/2015/04/system-1m-plus-digi-modules.jpg[/t] okay maybe a few more and some extra patch cables [t]https://i.ytimg.com/vi/x1Fni4XdIgI/maxresdefault.jpg[/t] WHAT YEAR IS IT [t]http://web.media.mit.edu/~joep/pics/PatchedCabinets.jpg[/t] all in the span of 6 months and $20grand

Yeah let me just add some nice reverb to my oscilloscope

[QUOTE=halofreak472;49148000]Yeah let me just add some nice reverb to my oscilloscope[/QUOTE] I mean, [URL="https://www.etsy.com/listing/150852288/pt2399-delay-dev-diy-kit?utm_source=google&utm_medium=cpc&utm_campaign=shopping_us_a-books_movies_and_music-music-musical_instruments&utm_custom1=dba92bb7-c3fa-49b6-aea3-7dfaeced0ae6&gclid=Cj0KEQiAg7ayBRD8qqSGt-fj6uYBEiQAucjOwcheC_lcY38nQsipJpBuX8oiji2ISd_-sk24CuRLMFcaAlqs8P8HAQ"] technically it could be done...[/URL]

Been laying out the board for my digital guitar pedal: [IMG]http://i.imgur.com/4x4vHk2.png[/IMG] It's just a Cortex-M4F with nice Sigma-Delta ADCs, some analogue filtering/buffering, USB and some battery + power supply stuff. Also been trying to get my room's impulse response by standing in different places and clapping: [IMG]http://i.imgur.com/HTwHn1n.png[/IMG] Should be able to just convolve the audio data with that, I'll have a reverb setting called "Luke's room" The board is pretty tiny, 30mm x 40mm. Any general criticism of it please?

You might want to move the top connector further away from the mounting hole, otherwise it look fine to me.

That tek scope was a fire hazard. No wonder it was as-is. You plug it into the bench and the breaker popped for the bench outlets. You ohm'd out the cable and hot shorted to ground. Better inspected the crunched portion of the cable and found that not only was the outer sheath damaged but the insulators were crumbling. If I put this thing on the isolation transformer it would of probably gone up like a heating element. Completely replaced the cable, cleaned a few contacts and after some adjustments it was totally happy. [IMG]http://i11.photobucket.com/albums/a166/ballsandy/CGS_1187.jpg[/IMG] [IMG]http://i11.photobucket.com/albums/a166/ballsandy/CGS_1185.jpg[/IMG] [IMG]http://i11.photobucket.com/albums/a166/ballsandy/CGS_1186.jpg[/IMG] I like how everything had their serial numbers scratched off. :v:

Today I tried to figure out if I could run my 40w lamp with 60w bulbs for slightly longer before burning everything down by using a peltier near the bulb attached to a heatsink on the other side of the peltier unit to power a fan for cooling the wiring/mounting for the bulb. After I burnt myself merely trying to hold my test rig together I decided that I was being a goddamn idiot, and I should probably just buy the right bulbs. And go to sleep. I was very tired. still am. wtf is happening.

Say I have a circuit like this [IMG]http://i.imgur.com/MkXb8kH.png[/IMG] and I want to find the amplitude of the steady state voltage across the load resistor using phaser analysis, whats the quickest way of doing it? I've tried it a few times, once just using the numbers give and the second time using algebra and replacing the numbers at the end, both times it's taken me over an hour and I've got the answers wrong. w(omega) = rad/s and A =4

[QUOTE=cathal6606;49158175]Say I have a circuit like this [IMG]http://i.imgur.com/MkXb8kH.png[/IMG] and I want to find the amplitude of the steady state voltage across the load resistor using phaser analysis, whats the quickest way of doing it? I've tried it a few times, once just using the numbers give and the second time using algebra and replacing the numbers at the end, both times it's taken me over an hour and I've got the answers wrong. w(omega) = rad/s and A =4[/QUOTE] Turn all the elements into complex impedances. Combine the capacitor impedance and resistor impedance in parallel to get one total impedance. and do the same for the inductor resistor pair. Then just use voltage division using the two impedances and the phasor voltage.

One of the fun things about old electronics is the circuits are relatively simple. One of the shitty things about broken old electronics is when you have to source a replacement for a transistor manufactured before we had even orbited the moon. :v:

[QUOTE=pentium;49178850]One of the fun things about old electronics is the circuits are relatively simple. One of the shitty things about broken old electronics is when you have to source a replacement for a transistor manufactured before we had even orbited the moon. :v:[/QUOTE] As with most things you don't need a perfect match, as long as the ratings for current, power dissipation, voltage and bandwidth are similar or better it'll work just fine. The only real exception is germanium transistors, you can get modern replacements for most of them, in the case of a power germanium transistors it'd probably be better to first try a silicon.

[QUOTE=Chryseus;49179209]As with most things you don't need a perfect match, as long as the ratings for current, power dissipation, voltage and bandwidth are similar or better it'll work just fine. The only real exception is germanium transistors, you can get modern replacements for most of them, in the case of a power germanium transistors it'd probably be better to first try a silicon.[/QUOTE] The substitutes I'm finding listed are equally as bizarre. I mean, it's old enough I dare say it could take a 3904 but I've yet to see a datasheet that says that yes, I can sub that in for this little fucker. [img]http://i11.photobucket.com/albums/a166/ballsandy/IMG_1862.jpg[/img]

And this is why I'm thankful we have JEDEC standards for packages and naming schemes (e.g. 1Nxxxx or 2Nxxxx), because good luck finding a datasheet or even an entry for it in an old databook. You're more likely to find some obtuse part number like that in one of those Chinese parts dealer sites (See Octopart, etc) instead of AllDatasheets.

[QUOTE=LoneWolf_Recon;49180259]And this is why I'm thankful we have JEDEC standards for packages and naming schemes (e.g. 1Nxxxx or 2Nxxxx), because good luck finding a datasheet or even an entry for it in an old databook. You're more likely to find some obtuse part number like that in one of those Chinese parts dealer sites (See Octopart, etc) instead of AllDatasheets.[/QUOTE] [url=http://alltransistors.com/transistor.php?transistor=15636]Dayum, what are the odds! :v:[/url]

So I've been playing with the thermal analysis feature in Solidworks in hopes of applying it to some projects where the thermal design will be very important. I made a basic model of this HSF, the Dynatron K2: [thumb]http://i.imgur.com/guYhouZ.jpg[/thumb] And applied an 82W source to it to see what happens: [thumb]http://i.imgur.com/0QlGBdk.jpg[/thumb] [thumb]http://i.imgur.com/Rmejp5u.jpg[/thumb] That's not good! The air is circulating and causing everything to overheat. But in most images I found, the fan's intake is 90 degrees rotated to the photo so let's see what happens then: [thumb]http://i.imgur.com/HadYrEp.jpg[/thumb] [thumb]http://i.imgur.com/NKV66cv.jpg[/thumb] Almost a 30 degree drop in temperature! Goes to show how important something as simple as that can be. This software is really incredible and insightful though. I'm having so much modeling and testing things.

I did a thing. [t]http://i.imgur.com/yqELCyG.png[/t] Need to design the board next week.

God fucking dammit. [IMG]http://i11.photobucket.com/albums/a166/ballsandy/IMG_1886.jpg[/IMG] [IMG]http://i11.photobucket.com/albums/a166/ballsandy/IMG_1893.jpg[/IMG] This is the fifth battery rebuild I've done and [i]again[/i] it failed to be any better than the original battery. I used slightly more reputable brand cells, it charges fine. A full-charge is 13.5v but after a dozen shots the camera kicks out with a low battery alert even though it's still only at 12.6.

[QUOTE=pentium;49203660]God fucking dammit. [IMG]http://i11.photobucket.com/albums/a166/ballsandy/IMG_1886.jpg[/IMG] [IMG]http://i11.photobucket.com/albums/a166/ballsandy/IMG_1893.jpg[/IMG] This is the fifth battery rebuild I've done and [i]again[/i] it failed to be any better than the original battery. I used slightly more reputable brand cells, it charges fine. A full-charge is 13.5v but after a dozen shots the camera kicks out with a low battery alert even though it's still only at 12.6.[/QUOTE] Did you check battery temperature? Maybe the camera is faulty and discharges the batteries really quickly. Try hooking it up with a current meter inbetween.

How do you calculate the loss of energy when converting AC to DC back to AC? :cry: [edit] or DC to AC back to DC

[QUOTE=false prophet;49223089]How do you calculate the loss of energy when converting AC to DC back to AC? :cry: [edit] or DC to AC back to DC[/QUOTE] You can measure it or estimate it. Depending on the quality of the regulator you'll get something between 70-90% of efficiency on every conversion.