Kim and Luke, thanks for the soldering tips and workflow. I am doing a lot of research about SMD soldering on Youtube. I am working on making a toaster oven I have into a reflow oven, which I think will give me the best chance for success with Kim's TCB Hat board. I see some folks do double-sided boards in reflow ovens by using a temperature sensitive expoxy under the chips when reflowing the first side. That may be the way to go, or am I overthinking it?
I've begun assembling the road wheels on the T-35a that I'm building from Dean Rauch's files. I've been trying to get an answer from him on what metal he is using as a leaf-style return spring on his bogeys, but so far no answer. I've tried contacting another fellow on Thingiverse who also built from Dean's files, but so far no response. I've attached a photo of what I'm talking about. I tried some galvanized steel sheet I had, but it was too soft. Perhaps stainless steel around 0.35mm?
Quote from: JPS99 link=topic=240.msg2488#msg2488 date=1599512813 The other thought that comes to mind is women's hair barrettes, but what are the odds they would be the right size?![/quoteWow, that's thinking outside the box! They would have to be fairly large, as what I've tried so far has been about 110mm X 12mm.I'll check the local Dollar Stores to see if they have anything like that. Thanks for the tip! (as well as the soldering guidance!)Joe
Wow, that's thinking outside the box! They would have to be fairly large, as what I've tried so far has been about 110mm X 12mm.I'll check the local Dollar Stores to see if they have anything like that. Thanks for the tip! (as well as the soldering guidance!)Joe
since the VNH chips are now on the bottom, do you leave that section of the board hanging off your hot-plate?
I suppose the surface tension keeps the VNH chips attached even as their paste melts again during the second reflow, but I can imagine it would be important not to knock it suddenly while hot! Have you had problems with that?
You are completely correct! I needed to look more closely at your schematic. I knew the VNH5050 chips provide a current measurement output and I just assumed you were using that, but I see you have a dedicated current measuring IC so you are right, your code can work with any motor drive type. I have changed the code back to the way you had it and posted it as firmware v0.93.71.It is a very interesting idea to regulate the model's behavior based on current draw and I would be curious to experience the difference in driving style that might give. Perhaps when I return to America I can try to build one of your boards so I can experience the difference first hand.
The whole idea of the wattage regulation was to make the model behave as their prototype meaning when the model goes through rough terrain it should slow down to a pace that reflects the prototype. A feature I would love to be implemented in the OP Config is the ability to set this max motor power. As it is now it has to be set in the OP_Driver.cpp
When you say the max power is set manually in OP_Driver, are you referring to this array: log_speed_curve_out[] ?If so, it looks like there are 5 numbers actually needed, corresponding to the desired max wattage for 5 segments on a logarithmic scale. Even if we make it possible to set these numbers in OP Config, I wonder how many people are going to have any clue what to enter? The final effect will seem to depend on the motors used, the gearbox ratio, the battery voltage, and the model's specific handling characteristics as influenced by its weight. Even if they have the ability to measure their own current draw (which most do not as I have discovered on this forum), it still seems like it will take a lot of trial and error over different terrain at different speeds to derive suitable wattage values. To me this just seems like something very, very few people are going to want to do or even be able to do. I am not saying it is a bad feature, in fact it is very cool, but it is not widely applicable.
float engine_max_watt = 50.0; float log_speed_curve_in[] = {0, speedLimit >> 3, speedLimit >> 2, speedLimit >> 1, speedLimit}; float log_speed_curve_out[] = {0.0, 0.02 * engine_max_watt,0.08 * engine_max_watt,0.25 * engine_max_watt, engine_max_watt}; setpoint = FmultiMap(desiredEngineOutput, log_speed_curve_in, log_speed_curve_out, 5); feedback = engine_watts;
From what I can see now, as much as I think your approach is very impressive and clever, I'm not sure I want to add a section to OP Config for these adjustments. The number of people who would use it is surely so small that it would be easier for the rest of the community if those few people compile their own custom hex files.To be honest, since your fixed values may not work for everyone, what might even be the better approach is to have the code function by default the way the standard TCB does. For those users who do want to use your custom wattage scaling, they would need to edit the code to enable it (set some variable to "true") and enter their 5 custom values. It would be best to put these options in a dedicated .h file rather than in OP_Driver, that would make it easier for the user and less likely they accidentally change something else. Then those users can recompile the code with their changes. But otherwise for people who want to use your shield but don't know anything about compiling code, the driving would already work like a normal TCB and they wouldn't have to think about any of this.
The soldering process I use is as follows:1. Reflow solder the VNH5050's. Check for bridging/gaps (using multimeter)2. Reflow most of the underside components, starting so close at you can get to the VNH5050's which are now upside down and hindering a complete reflow of the buttom. 3. Hand soldering the rest of the top SMD components4. Hand soldering the rest of the buttom SMD components5. Hand soldering the top through-hole components6. Hand soldering all of the pins going into the arduino mega. (mounting the pins in the mega using it as the holder is the easiest way to do it)Saying this is an easy soldering task would be a lie. It takes some practice to solder smd components of this size, youtube is your friend.I use a simple hotplate for the reflowing such as thisCheers Kim