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Synathaesia posted:Similar to what tonberrytoby said, the Neutral line on a three-phase AC line is common between multiple phases and will therefore be a return path for all current. When three phase systems are driving a motor, the current should be zero, if there's significant current on the N wire then something's broken.
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Jul 25, 2013 20:29
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So the family biz finally gave me a work truck, with two cig lighter sockets in the dash, both factory. My phone charger works with the one socket specifically mentioned in the manual for use with the lighter, but my phone charger will not work with the other socket labeled "power point". I tried my multimeter on both of them and they both test at 12V like they're supposed to. I checked the sockets and they're both in good shape, no cracks or anything, so it's not like the contacts aren't connecting when a plug is inserted. What would make one work but not the other?
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Jul 30, 2013 23:26
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Did you test the nonfunctional one with the engine on? The one in my vehicle is off when the key isn't in the ignition or the car isn't running.
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Jul 30, 2013 23:44
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There are two cigarette lighters in my car as well. One is always on, the other is set up by default to turn off when the engine is off and the door is opened (kinda like the radio). Both should work with the engine on.
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Jul 31, 2013 00:07
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Any suggestions for a "beginner" oscilloscope? I don't have a specific application in mind right now, but I'd like to add one to the equipment list while I'm redesigning and organizing the junk pile currently masquerading as my electronics bench. I also haven't hardly even laid eyes on one in almost 20 years, so I'll pretty much be starting over at the bottom of the learning curve. I guess my criteria at this point would be...inexpensive and two-channel? A little lost after that. 
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Jul 31, 2013 01:30
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Acid Reflux posted:I also haven't hardly even laid eyes on one in almost 20 years, so I'll pretty much be starting over at the bottom of the learning curve. I guess my criteria at this point would be...inexpensive and two-channel? A little lost after that. What's our definition of inexpensive in this context? Because what it comes down to is that you can pick up an old Tek 456 dual channel that has nasty pots and switches (and probably no probes) and in need fo calibration for $100 or so (what I did), or you can get something that is really pretty drat decent for like $300-$350.
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Jul 31, 2013 02:23
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Acid Reflux posted:Any suggestions for a "beginner" oscilloscope? I don't have a specific application in mind right now, but I'd like to add one to the equipment list while I'm redesigning and organizing the junk pile currently masquerading as my electronics bench. Search amazon and a bunch come up for <$500. If I were getting a scope for myself that's what I'd do. Personally I'd trade brand for price and modern features. On the other hand if you're comfortable with older ones going on ebay might be your best bang for the buck. Although the market for used scopes is pretty competitive. And another option: USB scopes https://www.sparkfun.com/products/9263 asdf32 fucked around with this message at 03:07 on Jul 31, 2013 |
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Jul 31, 2013 03:00
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If you can get over his funny voice (and I don't mean funny in a "laugh with him" sort of way) the guy over at eevblog reviews a lot of scopes, often with the hobbyist in mind.
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Jul 31, 2013 04:18
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I can safely budget about $300 right now, so I'll do some research and see if I can find a good deal on something solid. It can also wait, because as I said, it's definitely more of a want than a need right now. Thanks for the tips!
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Jul 31, 2013 17:09
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I picked up a Tek scope (250MHz? forget the model at the moment) off eBay a few years ago. The key thing is you really have to watch the market. Good stuff at good prices does show up, but you have to act fast.
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Jul 31, 2013 19:43
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I have an old Tek TDS420A that I found in the junk bin. It fails the Attenuation/Acquisition POST and one channel was completely fubar when I pulled it out. I'm reading everywhere that this is just a matter of replacing a poo poo ton of caps on the board, but I think it's a losing battle at this point. I started replacing stuff and instead of one channel gone wonky now it's just completely off the board on every channel. I might part it out on eBay or something since people love fixing poo poo like this up, and it has a bunch of useful boards like an external VGA hookup, etc. But it sounds like I just need to pick up a new DSO. Owning a DSO really spoiled me. I have an older Tek something-or-other analog scope that does pretty much everything I need other than .. well, signal storage .. but I can't help but feel like I'm banging two rocks together after having access to all the neat stuff my 420 did 
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Jul 31, 2013 21:15
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MRC48B posted:Did you test the nonfunctional one with the engine on? The functional one is always on and always tests at 12 volts, the noncharging one doesn't work regardless of the where the key is turned in the ignition or if the engine is running, but it also always tests at 12 volts.
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Jul 31, 2013 22:19
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kid sinister posted:The functional one is always on and always tests at 12 volts, the noncharging one doesn't work regardless of the where the key is turned in the ignition or if the engine is running, but it also always tests at 12 volts. Huh. The other thing I would try would be to make sure the plug is actually making good electrical contact. I've had 12v devices not work in some cars, because the socket was a different design. That's all the advice I've got. Sorry it's not more helpful. Weird problem, especially if it reads 12v on the multimeter.
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Jul 31, 2013 22:32
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kid sinister posted:The functional one is always on and always tests at 12 volts, the noncharging one doesn't work regardless of the where the key is turned in the ignition or if the engine is running, but it also always tests at 12 volts. Could it be that the little tab (assuming it has that style) for the socket's tip connection is bent back (or forward in this case) too far, preventing contact with the plug's tip? I've run into that in the past, but it's really not too common to find a plug you can't mash in far enough to overcome it. Another thing to look for is corrosion, however slight, at the socket's tip connection. It doesn't take a whole lot to interrupt current flow at 12V, but you can frequently still read the voltage. On that note...gently caress car electrical systems, right in their little drat lighter sockets. I'm an aircraft electrician/avionics box-swapper, and I'd rather gut and rewire an entire airframe than ever put my hands in another car's system. Ugh.
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Jul 31, 2013 22:37
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I know this comes up from time to time, but who what everyone's recommendation for low volume online PCB manufacturers?
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Aug 1, 2013 15:33
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Cyril Sneer posted:I know this comes up from time to time, but who what everyone's recommendation for low volume online PCB manufacturers? What's low volume / board complexity? For personal stuff, OSH Park owns because it's pretty high quality, 3 copies of your design for $5 per sq inch. For more than that...Gold Phoenix, Silver circuits, Advanced Circuits...depending on your needs, and time pressures.
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Aug 1, 2013 15:56
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movax posted:What's low volume / board complexity? For personal stuff, OSH Park owns because it's pretty high quality, 3 copies of your design for $5 per sq inch. volume-wise, maybe 10 units on the order of 3" x 3". In terms of complexity, primarily single layer stuff. edit: I should mention I'm in Canada so internationl shipping is a must.
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Aug 1, 2013 16:37
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So I'm trying to get better with hardware and soldering, I've always been a software guy. Soldered up a practice simple circuit, everything went pretty well, except its supposed to flash an LED on and off while making a siren noise, and instead it just gives me a solid light and a constant tone. None of the solder joints look too bad, everything seems like it makes good contact, so I'm guessing that I accidentally fried the 555 timer IC chip with too much heat? I'm happy that the volume pot works and the LED lights up and the speaker gives me a good tone, but the circuit definitely isn't working remotely how it should be. What temperature should I be working with for general electronics soldering? What for ICs? How would I go about troubleshooting a situation like this? I've got a multimeter and I poked around but didn't come to any magical revelations. I have some other things I wanted to work on next but I feel like until I figure out what I did wrong for sure here I'd just screw em up. Is there an easy way to test the IC with the multimeter to see if its still good? Seems you're pretty limited with just 2 contacts, I don't have a chip tester or an oscilloscope or anything. I guess I could plop the chip in a breadboard and make a chip tester out of an Arduino, (or buy a chip tester) but that'd take me a minute. Alternatively I guess 555 timers are pretty cheap, I could just grab another and swap it and see if that does anything. Hmm. Protips?
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Aug 1, 2013 16:47
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Double check your wiring first, as it sounds like it could be as simple as a short somewhere.
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Aug 1, 2013 16:59
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This used to be my Dad's stereo. The volume control has gone on it. Does anyone know where to look to find a replacement part? I'm not sure what it's called or what values it should have. I plan on cleaning it up and using it. I can solder well enough and know better than to play with charged capacitors.    
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Aug 1, 2013 17:35
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TomR posted:This used to be my Dad's stereo. The volume control has gone on it. Does anyone know where to look to find a replacement part? I'm not sure what it's called or what values it should have. It's just a rotary dual 60k pot. What's wrong with it? If it's just filthy you may get away with a few blasts of Deoxit. Otherwise, just look for one with the right packaging to fit where it needs to go (shaft diameter, length, etc) at Digikey or Mauser. Shouldn't be terribly expensive.
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Aug 1, 2013 17:41
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Zaphod42 posted:Soldered up a practice simple circuit, everything went pretty well, except its supposed to flash an LED on and off while making a siren noise, and instead it just gives me a solid light and a constant tone. How fast are you 'flashing' the LED? Something with a 5% duty cycle pulsed a few times a second is more than enough to trick your lovely eyes into thinking it's constantly on.
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Aug 1, 2013 17:52
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Motronic posted:It's just a rotary dual 60k pot. What's wrong with it? If it's just filthy you may get away with a few blasts of Deoxit. Precisely, just spray it in those holes and turn the pot back and forth for a while, and then do the same with all the other pots switches and linear pots while you're at it. E: isopropanol or any kind of deethylated spirits can also work, it just needs to wet the carbon track inside to get the dirt out and then ideally evaporate. I'm looking for a cheap supplier of custom quartz resonators, very low volume (10 crystals at the most). Standard plug-in package type for use in a set of old crystal controlled radios. longview fucked around with this message at 18:05 on Aug 1, 2013 |
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Aug 1, 2013 17:57
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Motronic posted:It's just a rotary dual 60k pot. What's wrong with it? If it's just filthy you may get away with a few blasts of Deoxit. It cuts in and out and makes a lot of static when you turn it. Sometimes it jumps around the volume when no one has touched it. My dad tried to spray break cleaner on it once and that seemed to help for a while. I'll look and see how much a new one is. It could be less than deoxit, which I don't have. Thanks a bunch.
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Aug 1, 2013 17:57
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TomR posted:It cuts in and out and makes a lot of static when you turn it. Sometimes it jumps around the volume when no one has touched it. My dad tried to spray break cleaner on it once and that seemed to help for a while. Brake cleaner is a super terrible idea, as it likes to eat plastics. After hearing that I'd suggest just replacing it.
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Aug 1, 2013 18:41
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MRC48B posted:Huh. The other thing I would try would be to make sure the plug is actually making good electrical contact. I've had 12v devices not work in some cars, because the socket was a different design. Acid Reflux posted:Could it be that the little tab (assuming it has that style) for the socket's tip connection is bent back (or forward in this case) too far, preventing contact with the plug's tip? I've run into that in the past, but it's really not too common to find a plug you can't mash in far enough to overcome it. Another thing to look for is corrosion, however slight, at the socket's tip connection. It doesn't take a whole lot to interrupt current flow at 12V, but you can frequently still read the voltage. So basically I need to find some way to to connect some jumpers to the socket's internal connectors and the charger so I can absolutely verify that they are making contact? Sounds fun. Any good ideas on how I can do that given the confines of a cig lighter socket? Backprobing is a no-go. I tried to get it out of the dash. There's maybe a half inch of clearance behind it and I would end up destroying the socket to work out the clips holding it in place on the dash. kid sinister fucked around with this message at 18:57 on Aug 1, 2013 |
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Aug 1, 2013 18:49
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Motronic posted:Brake cleaner is a super terrible idea, as it likes to eat plastics. After hearing that I'd suggest just replacing it. Yeah, I know. He was going to throw it out. I just cleaned it now with isopropanol so when it dries I'll try it again. I had a look and I could only find 50k pots. Edit: well I'll be damned, it works perfectly now and sounds great. Thanks for the isopropanol suggestion longview. TomR fucked around with this message at 19:15 on Aug 1, 2013 |
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Aug 1, 2013 18:58
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Zaphod42 posted:So I'm trying to get better with hardware and soldering, I've always been a software guy. You would need an oscope to check the behavior of the circuit. My guess is you've swapped a resistor or something. if you get a tone, it is oscillating. Your lovely eyes can only see blinks <60Hz or so. If you are hearing a tone, it's probably 100+ Hz. The light appears on but is blinking correctly. Do you have a schematic? It would be easier to take a stab at a more specific guess if I could see the layout.
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Aug 1, 2013 20:18
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What's the simplest RF switch? I need some handheld control to operate a very, very small device, likely running on a CR2302 or similar button cell. Either "on while press" or a 3-second burst for each press of the button. Is there some off the shelf solution I can have shipped to me tomorrow or is this a lot more complicated than I'm imagining?
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Aug 2, 2013 00:07
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Delta-Wye posted:You would need an oscope to check the behavior of the circuit. My guess is you've swapped a resistor or something. if you get a tone, it is oscillating. Your lovely eyes can only see blinks <60Hz or so. If you are hearing a tone, it's probably 100+ Hz. The light appears on but is blinking correctly. Do you have a schematic? It would be easier to take a stab at a more specific guess if I could see the layout. I was gussing that's it's just an on/off buzzer with a fixed tone and that the 555 was turning the tone and the LED on/off simultaneously at a human detectable speed? Anyway, welcome to hardware. I don't think I've ever burned a chip with heat and I'm not good at soldering. So I don't think that's too likely, especially held up against the probability that you botched something else (no offense). I think you've just got to double check the circuit. Look it over, check the solder joints, then check for power in places where you expect power etc.
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Aug 2, 2013 00:09
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JawnV6 posted:What's the simplest RF switch? You might be able to do it with a simple pin diode arrangement. You apply some +V to turn on the pin diode and then, depending on the desired behaviour, it either inserts or bypasses a tuned LC circuit on your RF line.
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Aug 2, 2013 03:17
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JawnV6 posted:What's the simplest RF switch? Are you looking for a solution to turn a RF signal on or off or a remote controlled switch solution?
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Aug 2, 2013 10:15
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Does anyone know where I can buy about 400 ft. worth of 20 - 24 awg insulated (not enameled) hook-up wire for a good price? All I can find are little 15 ft spools, or multiple-thousands off Alibaba.
Cyril Sneer fucked around with this message at 15:09 on Aug 2, 2013 |
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Aug 2, 2013 15:06
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That sounds an awful lot like thermostat or doorbell wire, both of which will be available in any big-box retail hardware store.
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Aug 2, 2013 15:38
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insta posted:That sounds an awful lot like thermostat or doorbell wire, both of which will be available in any big-box retail hardware store. Those aren't really "types" of wire, just uses. Anyway, 18-20awg is what is typically used in doorbell/thermostat wire. And you're not going to get 400' for cheap at a retail outlet. Hmm. Found this: http://www.amazon.ca/Coleman-Cable-94601-66-18-500-Feet-2-Conductor/dp/B0002YXMJA that its paired will be helpful routing-wire, but its effectively twice the length I need. With free shipping though, its the best price I've seen. Cyril Sneer fucked around with this message at 15:49 on Aug 2, 2013 |
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Aug 2, 2013 15:45
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Beware that the low voltage wiring for thermostats has the _worst_ poo poo trash insulation you've ever seen. You even look at the outer jacket wrong, boom you just nicked three inner conductors. I mean, I'm an old beard at this poo poo, and I had to re-strip the first end four times. Jesus.
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Aug 2, 2013 16:02
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Cyril Sneer posted:Does anyone know where I can buy about 400 ft. worth of 20 - 24 awg insulated (not enameled) hook-up wire for a good price? All I can find are little 15 ft spools, or multiple-thousands off Alibaba. http://www.bulkwire.com/ has about the best prices I've been able to find.
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Aug 2, 2013 17:20
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asdf32 posted:Anyway, welcome to hardware. I don't think I've ever burned a chip with heat and I'm not good at soldering. So I don't think that's too likely, especially held up against the probability that you botched something else (no offense). I have a schematic, but its on paper. Here ya go.  Maybe I should have mentioned its a PCB, not just a breadboard/wires ? So.. how can I test that things are working properly? That's my question, how do I troubleshoot next. I can't detect current without putting a meter in series, right, so I'd have to like cut a trace (nope) or de-solder something and then hook up between it and the mount point. Doing that for every component would be the same as just re-soldering everything and hoping that fixes it. The speaker is just a simple speaker, I used the same speaker connected to the GPIO pins of my arduino to play a simple song using PWM. So I guess the 555 chip is working to generate the sound. So its just some of the inputs to modulate the signal aren't getting sent... Zaphod42 fucked around with this message at 19:33 on Aug 2, 2013 |
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Aug 2, 2013 19:31
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longview posted:Are you looking for a solution to turn a RF signal on or off or a remote controlled switch solution? Zaphod42 posted:So I guess the 555 chip is working to generate the sound. So its just some of the inputs to modulate the signal aren't getting sent...
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Aug 2, 2013 19:36
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JawnV6 posted:I'm not convinced you actually have a problem besides expectations. A LED can appear "on" to human eyes when in reality it's pulsing. Even without an oscope, you can detect it with a camera or record the sound and pull it up on a computer. I'm pretty sure it should be flashing one LED when the other is off, and flashing the other when the first is off. And again, there should be pauses in the tone, and the tone should change to different frequencies. None of that is happening. Both LEDs are full on all the time, and the tone is constant. Looking at the schematic, (oh god I'm terrible at this  ) I'm not sure if the LEDs would switch or not, but the tone should definitely be switching somehow. Its supposed to emulate a European police siren sound.Appreciate the assistance. Zaphod42 fucked around with this message at 19:48 on Aug 2, 2013 |
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Aug 2, 2013 19:44
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