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Possible Shield Requirements Analysis
05-31-2014, 02:52 AM
Post: #31
RE: Possible Shield Requirements Analysis
(05-31-2014 02:22 AM)steamboat Wrote:  Can't find the MAX4372T in this shop.

But found a LTC6101BCS5 for 2,59
and a LTC6101AIMS8 for 3,22

In the other German "all people shop" Reichelt I also can't find any of this...

Unless you think otherwise I am not going to worry about non-USA available SMD components as I am going to do the SMD assembly myself. If you want to give your self a go at SMD reflow I'll just send you a bunch of parts with a few extra PCBs.

In this particular example I think it might just be an older part, i took look into all these we have found and then order it and do a quick test as a proof of concept.

Once I have a stencil its just a matter of a lot of tweezer work and making sure your placing the components in the right spot, drop on the hot plate, and then make sure nothing shifts. Sometimes I have to run a hot iron over fine pitched legs that may have fused together. But its pretty easy, just time consuming with the tweezer Wink
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05-31-2014, 03:07 AM
Post: #32
RE: Possible Shield Requirements Analysis
(05-31-2014 02:52 AM)jmccartney Wrote:  Unless you think otherwise I am not going to worry about non-USA available SMD components
For me this was only a test what kind of chips you can find in a popular shop. Everything else of course is also sourcable here in Germany...

Rainer
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06-01-2014, 04:56 AM
Post: #33
RE: Possible Shield Requirements Analysis
Here something similar

http://www.ebay.com/itm/251500805418

But for 30A so the resolution is not good.

If it is to complicated to place it on the board, we could place it into the servo itsef. There is enough space. Than we have to wire the output to any free A/D-pin...

Rainer
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06-01-2014, 06:47 AM
Post: #34
RE: Possible Shield Requirements Analysis
You also can get the ACS712 in a 5A version:
http://www.ebay.de/itm/New-design-5A-ran...2a2605f2b6

Maybe still a to bad resolution with 185 mv/A

Rainer
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06-01-2014, 10:01 PM
Post: #35
RE: Possible Shield Requirements Analysis
(06-01-2014 06:47 AM)steamboat Wrote:  You also can get the ACS712 in a 5A version:
http://www.ebay.de/itm/New-design-5A-ran...2a2605f2b6

Maybe still a to bad resolution with 185 mv/A
Funny you mention it, I was looking at this before I went to bed, but the part might not be that great besides being widely used. Resolution is not awesome as well as its not cheap $4us for me to source.

I did manage to shift things on the board enough to make room for this I think. Because of the nature of how things are already layed out though the current sense ic will monitor an entire 3 channel servo port. So in other words 2 of the 4 3 channel servo ports will have current sense. It just seems to hard to isolate a single servo channel at this point.

I'll post a picture of what I am saying, its hard to put in words that are not confusing.


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06-02-2014, 01:04 AM (This post was last modified: 06-02-2014 02:54 AM by steamboat.)
Post: #36
RE: Possible Shield Requirements Analysis
Great - that's a lot of work to shift all this tiny wires around what nobody ever see afterwards...
I like it!

Rainer
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06-08-2014, 07:23 AM
Post: #37
Emoro
Do you know Emoro?
http://www.inovatic-ict.com/didactic-equ...assic.html

[Image: EMoRo%20USB%20Classic%2018cm.png]


Looks a little like Sho's Shellmo Board:
[Image: shellmoboard1.jpg]

Rainer
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06-14-2014, 12:46 AM (This post was last modified: 06-14-2014 12:50 AM by jmccartney.)
Post: #38
RE: Possible Shield Requirements Analysis
I split off all my "power supply" features into a 5cm x 5cm PCB. I did this for two reasons, I want to test these circuits out on a smaller board, and I am on the fence with integrating power into my shield or not. I might just put a header for this board if it works correctly.

Features:
5v 400mA Switching Boost Regulator
3.3v 150mA LDO Regulator
Dual N-Channel 3.0A 20V MOSFETs
N-Channel Logic Level 6.5A 30V MOSFET
Optional Li-ion/Li-Poly Charger
Optional Li Fuel Gauge

Telemetry:
High side current sense and voltage @ pwr rail, 5v, and 3v3 via analog
Li fuel gauge measures battery voltage, charge via I2c

Control:
switch power leds and voltage reading
3 mosfet switches for pwr rail

Misc:
I added a bunch of different jumpers that will allow for different power setups such as:
power regulators via lipo and pwr rail via separate battery
power only by dc barrel or usb
charge lipo by dc barrel, usb, or separate battery.

Other notes:
The diodes off of the dc barrel and usb ports are used to burn off some power to bring voltage below 5v. This is inefficiency by design because I want to keep the high efficiency boost regulator happy while maintaing the ease of non-battery power for development purposes.


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