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jovial_cynic posted:I'm doing some wiring in my car, and I'm a bit of an indicator junkie. I've looked online for a correct diagram for an indicator circuit that would tell me if a fan failed. Well, fan, fuel pump, etc. You're looking for a current sensor. Put a low-value resistor in line with the line (do your math to make sure it can dissipate the power) and measure the voltage across it. Then you'll know your V, you know your R and so you can calculate your I. Most of the time I see current sensors configured with a comparator to a voltage reference, but beyond that I'm not too sure.
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Mar 30, 2014 19:39
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| # ¿ May 21, 2024 12:17 |
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give us a bit of context. underwater? harsh environment? My immediate thought is to mix in a bit of aluminum/brass powder with whatever threadlocker you otherwise prefer. That plus the forces on the thread faces should ensure plenty of conductivity.
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Oct 5, 2016 07:33
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That's just a switch. Symptoms indicate that something is failed short, switches and pots usually fail open. My guess is rising line voltage from the lightning spike caused the amplifier transistor in the thing to get its voltage rating exceeded and it's failed short now, which would pop the power supply as you're seeing.
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Oct 17, 2016 02:28
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Slanderer posted:it's not just a switch, it sounds like a dual audio pot w/ switches at the detentes. they're not really uncommon. idk about the rest though. [The problem]'s just a switch, not the device i know what a switched pot is lol. Sorry, bad phrasing.
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Oct 26, 2016 06:39
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if y'all dig soldering and hacking in all its forms, i'm now streaming electronics, ham radio, and general diy hacks 3 nights a week on twitch https://twitch.tv/mattyzcast last couple of sessions we've been trying to break/beat on conway's game of life on an Uno with an 8x8 LED display and a 4x20 LCD for stats, here's a fun clip https://clips.twitch.tv/StrongRockyPepperKappaRoss this is kinda self promo stuff, pls dont ban, i am affiliate but all money i make off the stream gets rolled right back into parts/materials for more projects to hack on during the stream we have a good time every time. i'm not very good at c, not very good at low level engineering, but i love running the stream so much and i hope you tune in and share my joy! we stream 7pm tues and thurs nights Mountain, and 3pm on Saturdays
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Mar 1, 2019 06:24
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Sagebrush posted:A student came in today with her guitar amp and asked me, as the Professor Who Knows Electronics, to take a look at it. I don't know a whole lot about audio electronics specifically but we opened it up anyway. It's a transistor amp -- inside is just a ton of of capacitors and resistors, some TO-220s that I assume are the output stage, and a number of ICs on carrier boards, with a rack of potentiometers on the front end as the equalizer. Forgot to get the part numbers of the ICs but I assume they're the actual amps. I didn't see any popped capacitors, burnt components, or loose solder joints. smells like some analog part is going into oscillation at a freq above audible range and locking up doing all its work up there. I'd check bypass caps (lil' ceramics) and filter caps. Feedback networks in amps are usually relatively low current, so I don't think it's a fried resistor.
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Mar 2, 2019 19:35
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Sagebrush posted:
PSU filter caps generally don't work at high frequencies. this is definitely something arcing. I'd try small capacitors (100 pf -> 1 nF range) between each line and ground. Barring that, there are differential SPI transceivers you can get to turn it into balanced data across cat5 pairs. I had to use that when I ran a 100 ft SPI line up to an accelerometer on my radio mast.
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Jul 7, 2019 17:47
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Cleaned up the desk and added my new Shenzhen Special DOS-1102 scope. Now seeking projects. Might gently caress around with a small HF transmitter, I've got a bunch of QRP crystals. And yes i love my $10 hamfest Fluke RMS meters with questionable calibration 
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Jul 12, 2021 06:41
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It's also why youll find 'explosion-proof' keys from old Navy ships and stuff. Won't derail too much but we have a whole world of wonderful code keys you can investigate in ham land. My favorite are the 'bugs' or semi automatic keys. These were developed because too many Morse operators were getting some syndrome that they'd call "telegrapher's arm" or something charming like that, but what we now know as RSI.  Press left on the paddle for a manual contact; this is what you use for dashes. Press right though, and a pendulum + spring mechanism makes repeated dots. Adjust the speed of them by moving the pendulum weight forward or back. This operator has added a couple of coils of solder for extra weight on the pendulum, to slow it down a bit more (they were built for commercial ops who would crank it out around 30-40 WPM; a lot of hams tend to hang out around 20-25) Switches are neat.
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Jul 14, 2021 17:18
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Mmm yeah. There's a company called Vizkey that still makes some wonderful bugs, including several vertical models. Main reason being that the pendulum length (which dictates the oscillation period) is no longer limited by the depth of your desk.
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Jul 14, 2021 17:41
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drat, now you've got me chomping at the bit to build a nice portable battery or two for my ham radio park adventures. I only need like 100Wh or so, but having a couple or three units might be great.
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Jul 16, 2021 07:11
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I'm thinking for the mic tapping problem that a highpass filter is in order. Is this intended to normally transmit the human voice? There's not really any useful information below about 120-150 hz or so, you can chop freely below there.
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Jul 16, 2021 19:22
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Diode pairs like that are very ubiquitous in radio land because their characteristics are just about right for clamping RF energy that receivers are Just Not Meant For and radios are built to be able to sanely take signals varying over about a 100-120 dB dynamic range. The signal gets very ugli-fied, but it does save the "can hear a mouse fart in a hurricane" front end transistor in a receiver.
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Jul 17, 2021 21:09
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Ambrose Burnside posted:the oscilloscope has landed. first impressions: god drat i need to pick Projects that take up less physical real estate i literally bought an 1102 chinascope because though i love my tek 2235, the thing's longer than a Thursday in summer.
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Jul 20, 2021 00:10
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Speaking of Adafruit, I snagged two of these today because I love my Pi400 and this thing has potential: https://cdn-shop.adafruit.com/product-videos/1200x900/4863-07.mp4 What is interesting is that they show things besides LCD's plug in, so i think it's basically a generic gpio 45 degree extender. so all manner of weird displays and input hats would be a fairly ergonomic option
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Jul 23, 2021 05:57
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This is slightly electronics-adjacent. I want to reverse the polarity of a motorcycle digital dash. simple LCD. normally black characters on a white-ish backlit BG. I want to swap the lighting for red LEDs and invert so that the digits and indicators show up red on a black(ish) BG. I've seen projects on this but a lot of them are from different types of displays and I'm nervous about ripping an OEM cluster. How tricky is it to install a new sheet of polarizing film rotated 90 degrees, generally?
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Aug 3, 2021 06:55
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You can play with the foam fill, too. I know a lot of ~~~ car audio ~~~~ dorks are using fiberglass pack or whatever to basically drop the resonant frequency of sub boxes
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Aug 14, 2021 05:20
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| # ¿ May 21, 2024 12:17 |
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Were it me i'd take one of two paths: If there's enough thread to mount it level without additional spacers, i'd go to home depot and buy tiny washers or perhaps cut them out of aluminum cans with a hole punch or something. If there's not, i'd grab some spacers with a female and male thread, chuck them in a drill and run them up against a file to grind them down to the appropriate height on the hex part.
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Aug 16, 2021 08:17
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