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About johnsmith1212

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  1. Ill limit you with the boring details, but I have an electronic device that I can attach to my bike tire and it produces power and in return it can apply resistance to my wheel to simulate a steep hill or I must produce a certain number of watts. Its a great tool for training.... I heard a pop and then took apart the unit to find a burned spot on the PCB. I later found the fried SMD melted to the inside of the plastic housing. Looking at everything, I found a part number for the replacement resistor and I plan on ordering that first. Ive never had to solder or mess with SMD parts before so I need advice on what to do, and what not to do. Im sure this was caused by an over-voltage, but Im extremely green, so if anyone can tell me what I should be checking out in addition to the resistor it would be greatly appreciated. Finally, what should I do about the hug burn on the PCB? Replacing the PCB is more than I have to spend, so I have to repair it. Recap: I burned a resistor off the pcb, I want to repair it, what else should be checked, how do I clean the huge burn? Click this image to show the full-size ve
  2. Hi, I need to measure the strain in concrete beams. For this purpose I have purchased data acquisition system with a complementary 1/4 whetstone bridge circuit. The complementary circuit consists of 3 resistors of 120 ohm each. My strain gauge is 120 ohm and the gauge factor (k) is 2.11. The data acquisition system is modern and digital. Now, after connecting the strain gauge to the complementary circuit and exerts excitation (Ue) of 2.0 V (output) to the whetstone circuit and then loading the beam so that strain happens and the data acquisition system reads the voltage from the whetstone bridge (Ua)(input) that varies due to the strain in the strain gauge, my question is: Is it possible to use the formula: strain=4 Ua/(k . Ue) Why should I do calibration? and why the strain is not programmed to be calculated automatically to the above formula? The data acquisition system requests the k, Ue and the whetstone bridge type (1/4, 1/2, or full) so that it has all the necessary information for calculating the strain but will not work without calibration data!
  3. Hello all, I am sure many have seen the debates on the internet by the car audio guys of the cheaper CCA wires vs pure copper wires when used to deliver high amp DC current. I am here to ask your opinion based on my situation. I have a 300w solar array, 400ah of 12v batteries, and a 50ft round trip circuit to my 2000w AC inverter using 1/0 AWG copper clad aluminum wires which I put together 2 years ago and is functioning off-grid correctly. I went with cheaper CCA vs welding wire or marine wire at the time because of the cost. After reading and watching many CCA (copper clad aluminum) vs OSF (oxygen free copper) videos, I was concerned my cables and crimp connections were a fire hazard. I went ahead and inspected all my connections and found zero marks of heat or corrosion. I also tried to run my circuit at maximum load (12V-150A) for a prolonged period and there was no heating up at any of the connectors or in the cables. The cons about CCA wire that people were mainly bringing up are: 1. the corrosion of the aluminum at the crimp terminals, which in turn creates resistance and heat. 2. higher resistance of aluminum causes higher voltage drop over distance, and heating of the lines. All my connections are heat shrunk, I found no signs of corrosion or heat damage after inspection after 2 years of use. The next thing is voltage drop. Many on the 'internet' claim that CCA cables have high voltage drop when it comes to delivering DC over distance. I did a volt meter test and this is what I found: All chargers and loads off: At the battery terminals: 13.01V At the inverter terminals 25ft away: 12.98V (50ft total distance including positive and ground lines of 1.0 AWG copper clad aluminum wire) My question is: should I go through the trouble of rewiring my entire setup ? Is it unsafe ? Am I losing performance ? It's about 600$ worth of cable, connectors and supplies where I am. All my wiring is nicely secured using adel clamps and terminated with quality connectors and I really don't want to rip it all apart. Tags: xe tai van dongben, gia toyota fortuner 2017, gia mitsubishi new outlander 2017
  4. Hello! I recently got an Off-brand arduino kit as my first taste of electronics. It came with the board, components like LEDs resisters, breadboard, jumper wires etc... the problem is that when I try to plug some things into the breadboard, it rarely works. I struggle to plug anything in and when I do, I pretty much have to hope that I plugged it in right, have to check all the connections constantly and plug some of them half way to get it to work. the most I've been able to do is three flashing LEDs. It is so scetchy that if I bump the table a tiny bit, it stops working and I have to redo the entire thing. In a month, I will get a actual Genuino Starter Kit to replace this one. My question is, are good quality breadboards easier to work with. In every video I've seen, they pretty much just plug the electonics in and it instantly works. Is it really that simple, or more like the experience I already got? Tags: giá xe toyota fortuner 2017, xe tai 8 tan isuzu, giá xe toyota vios 2017
  5. Hi All My ViewSonic monitor quit working and I know it is many times a capacitor issue and in the ViewSonic case, in the power supply unit. I pulled the power supply and I can see various locations where capacitors/other components leaked. I posted a picture of what I found and have a few questions about the components. The arrow labeled "A" points to three components that appear to have leaked. What type of a component are they? The arrow labeled "B" (middle bottom up arrow) points to another light blue component. This is a capacitor, yes? The last arrow "C" points to the leakage in the area of the large capacitor and a light blue component. The capacitor looks fine with no "bulging" but the light blue component is not big enough to supplied that magnitude of spillage. Any comments on how to address the issue there? Finally, I am wondering if the magnitude of failure is worth trying to fix. A new monitor of this size is $100-$140. Thanks for helping me learn. Tags: hd700 đông lạnh, giá toyota vios 2017, hyundai hd72
  6. Hello everyone, It's been years since I've posted here, and I remember there was a "chit chat" forum, but couldn't find it; please move my post to an adequate forum if it doesn't really belong here. I am working on the translation—from English to Spanish—of the essay "Demystifying Single-Supply OpAmp design" for a course in my Alma Mater, and I would like to know if it would be okay to post it, after it's finished, in a freelancer website as a sample of my work. The essay is found free at the EDN Network website, but since I probably have to post somehow the original for reference and I'm still not sure if it's okay to provide a link for it, I'm still not sure if it would be okay, really; I don't know of the possible legal issues of it. I won't be using it to claim authorship or anything, just reference. Thanks in advance. Tags: xe toyota camry 2016, xe tai dong lanh, gia xe toyota yaris 2017
  7. I just bought a new house. On one wall in the kitchen is panel with 3 switches. I have know what 2 of the switches do (both are ceiling lights), but the third one does not seem to do anything at all. My first thought was that it controlled one of the outlets in the kitchen or family room right next to the kitchen, but after taking a small lamp around to every outlet that I could find I could not identify what the switch was for. During my testing, every outlet tested had power and lit up the lamp ( I did not test the voltage at the outlets, though). So the next thing I did was take the cover plate off the switch panel and tested the voltage going to the switch in question. I tested by touching the wires going into the switch without removing them from the switch. With the switch in the on position I got zero voltage (Actually it was 0.016V), but when I put the switch in the off position I got 60.2V. I am not an electrician so I have no idea what this means. I do know that there are different types of switches (2-way and 3-way) and the one in question is a standard single switch. Now while I was checking the Voltage I did notice that some of the plastic body of the switch was cracked and broken and some of the material was actually missing. So I guess I have a couple of questions: 1. What would cause the voltage to only be 60.2V? 2. Could the broken material on the switch be causing what I am seeing? 3. How can I possibly determine what this switch is supposed to control? This is of course a very hard question for folks to answer but I am hoping maybe there is some trick for figuring this out. I am just worried that there may be some 'hidden' problem in the walls. Don't want an electrical fire. Thank you for any help you can give me. Tags: gia xe yaris 2017, hyundai hd700 đồng vàng, giá toyota camry 2016
  8. Hello, Yesterday I was watching a movie, and my HK AVR 147 just stopped working, and I could heard the relay switching off. I turn off the amplifier, and turn it on after 2 minutes, and it started to work for about a couple of seconds, and stopped again (again with a relay noise). Now, it doesn't work at all. I power the amplifier, it stays on standby (amber color). When I hit the button to start the amplifier, it turns blue, but with no relay switching noise. After 10 seconds, it returns automaticaly to Standby mode, with the amber color. Could anyone help me on this matter? I already checked the fuse, and it's OK. Tags: giá xe hd700, toyota altis 2016, xe hyundai hd72