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| Circuit for MosFets in parallel for extra current capacity.(Solved) |
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| David Hess:
--- Quote from: spec on January 01, 2019, 04:00:25 pm ---Before, I got the hang of decoupling, stopping, etc, I went though a phase where everything I touched oscillated, unless I tried to make an oscillator that is. --- End quote --- The first time I ran into this problem was when I was like 13 and had hooked up a 7805 regulator to my 723/2N3055 based bench supply. How does a 5 volt regulator running on 8 volts put out 12 volts? One 0.1 microfarad ceramic disc capacitor at the regulator's input solved it. --- Quote from: spec on January 01, 2019, 04:14:54 pm --- --- Quote from: David Hess on January 01, 2019, 02:22:50 pm ---The safe rule of thumb is to include a lossy element on at least one lead of any transistor. Strong decoupling and a capacitive load are especially problematical. --- End quote --- Good idea, presumably a lossy feritte bead would be one way. --- End quote --- There are a bunch of different ways to handle it as shown in the article attached below. A ferrite bead is usually more expensive than a resistor and a resistor also serves as a fuse but I have used either way depending on the application. |
| Jim-0000:
--- Quote from: Niklas on January 01, 2019, 01:42:26 pm --- A small switch, inserted on the control signal between the receiver and the speed controller, and a pulldown resistor (10k, signal-GND on the ESC side of the switch) could be an alternative. The control signal wire is either yellow, orange or white and the GND wire is usually black or brown........ --- End quote --- Excellent suggestion Niklas! I know that if the good quality ESC's that I use do not receive a control signal, the motor will not operate. I think this might be the solution...........and a very elegant one at that! --- Quote --- If you use an extension cable, then you don't need to modify the speed controller itself. --- End quote --- I will probably cut the servo lead signal wire and hard wire the switch in series with it including one end of the resistor and the other end to earth. I try to avoid servo lead plugs and sockets wherever possible. We know there are too many poorly crimped servo extension leads around on the market. I have drawn a little sketch to confirm if I have interpreted your suggestion correctly or not. Please check it for me. I will be trying this out on the bench before the day is finished. I will cut up an extension lead for test purposes first, before hard wiring the switch and resistor in the ESC receiver lead as described above. Many thanks, Jim. |
| bitbanger:
Three phase BLDC ESCs can be quite complex (much more-so beyond just this parallel issue) even for the hobby realm. I'm never one to knock anyone's ambition but have you considered that you can buy these readily? However perhaps this is being integrated into an existing PCB? Either way, this doesn't address the parallel question directly but you may find the below reference designs helpful: https://www.st.com/content/ccc/resource/technical/document/user_manual/group0/06/a3/c1/ae/7d/27/4c/e0/DM00384353/files/DM00384353.pdf/jcr:content/translations/en.DM00384353.pdf https://www.infineon.com/dgdl/Infineon-Application-Motor_Control-Drone_Electronic_Speed_Controller_ESC-TR-v01_00-EN.pdf?fileId=5546d462580663ef015843a229fe54ea |
| Jim-0000:
--- Quote from: bitbanger on January 02, 2019, 04:17:18 am ---Three phase BLDC ESCs can be quite complex (much more-so beyond just this parallel issue) even for the hobby realm. I'm never one to knock anyone's ambition but have you considered that you can buy these readily? However perhaps this is being integrated into an existing PCB? Either way, this doesn't address the parallel question directly but you may find the below reference designs helpful: https://www.st.com/content/ccc/resource/technical/document/user_manual/group0/06/a3/c1/ae/7d/27/4c/e0/DM00384353/files/DM00384353.pdf/jcr:content/translations/en.DM00384353.pdf https://www.infineon.com/dgdl/Infineon-Application-Motor_Control-Drone_Electronic_Speed_Controller_ESC-TR-v01_00-EN.pdf?fileId=5546d462580663ef015843a229fe54ea --- End quote --- Thanks for the post Bitbanger. However, we appear to be at crossed purposes. Either that, or you have replied to the wrong thread. Your post has me mystified; I apologise if I may have communicated the wrong message along the line. Please explain, what is this "parallel issue"? I already have ESC's (Electronic Speed Controllers plural!). I have no intention of building one any day soon, and most likely, never will. They are readily available, cheap and of good quality: as you suggest. The aim of this project is to design and build a device that will safely switch the power supply (in this case, a Lithium Polymer 14.4 volt battery), to an already existing ESC. Not to make one. Jim. |
| Jim-0000:
--- Quote from: Niklas on January 01, 2019, 01:42:26 pm ---I................................... A small switch, inserted on the control signal between the receiver and the speed controller, and a pulldown resistor (10k, signal-GND on the ESC side of the switch) could be an alternative. ........................ --- End quote --- Niklas, Success! I just did a test on the bench with a cut and modified servo extension lead as per my little circuit diagram above. It works perfectly..........the motor will run with the switch on and not run with it off regardless of the throttle stick positon. Very good, thank you for the creative suggestion. :) Thanks to all contributors. Jim. |
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