davebmw wrote:Still, you could just call them and ask, it would probably cost similarly and be more of a pain anyway, so they may not mind.
It will certainly cost more as its a one off and will be a pain but its going to be worth it I will pop them an e-mail just to see what they think.
I think it's a good call to leave it up to TA to make this call. I agree we should honor them. Personally if I'm given the choice of soldering it myself vs. purchasing it already done, I'll pay for thier's.
Here's a picture of the thru hole / SMD module. I'm not certain if this should work or if I'm dreaming. I'm still learning KICAD.
I've got the real files in the freeEMS thread. Perhaps someone can check and see if this might work, or if I'm missing some basic theory on it. My biggest concern is that I made it with a series of pads, then I labeled three of these pads as 1 and three of them as 2. I don't know if that will cause problems or not.
Any recomendations about what foot prints we should have for what parts? I took a stab by calling all resistors the R4-SM0805 and I'm sure a similar footprint will work for diodes that will be called D4-SM0805.
I think the only resistor that won't be in this footprint is the R1 from the regulator circuit. Any others that might not fit the bill?
What about caps? Should I go with the same thing and make a
I'm currently looking at the fuse, I don't know what current it should be hard set for, I also don't know what temp copper burns up at. Anyone know what those parameters might be.
Right now I'm looking at 2oz/ft^2 10 amps and a temp increase of 200c. For a trace width of about 60 mils, or 1.5mm. Anyone got a recommendations for how real that might be, should I think of using 5 amps instead of 10 amps? ect.
Don't forget there are 3 power inputs. The two regulated ones only need <1Amp each except when you first hook it up to fill any caps. The other one will have forward and backward current flow due to catching spikes with it. How much current for the third pin, I really don't know.
I think the majority of the power will be from the TA board, can you put a meter yours and see what it claims? I'm not so worried about spikes when it comes to the fuse. I think we'll discover this will be a slow blow fuse, so spikes won't bother it much.
The inductive driving circuits should be quite high impedance, I know I drew it up with the 12V for the injectors going through the board, but I only left it that way because of the Dsnub. I've been thinking of removing the 12V from the injector circuit. That's about the only other chance of having high power requirements.
So I think a good starting point is about 200% what ever current your TA board is currently using.
I'd budget on 500mA for each reg circuit and fuse for 2 Amps. As far as the other one goes, I would like to see a third 12v feed in the case fused to 5 or 10 or 15 Amps even if you aren't using it at the moment. We should put it there so that someone that needs one leaves the important feeds alone.
We also need to be very careful about which components are fed from which clean supply. eg does anyone know what the quiescent current of the MAX chip is? Actually, we have no choice for those parts, I hope they don't draw much or that is a serious thorn in our side indeed.
