Scorpion Controller Board

Project to send a balloon into lower space with payload
Rris
Posts: 66
Joined: Mon 12 Oct 12 2009 9:17 pm

Re: Scorpion Controller Board

Post by Rris » Thu 09 Dec 09 2010 12:11 am

Still need to add:
* inductor from the micropsu to the GPS input supply. Perhaps a couple of the bigger MLCC caps i have reels of as well.
* Inductor for the aerocomm (ultra low resistance) and another bigass cap (another 470uf/6.3v tantal?)
* Aerocomm connector on bottom
* Aerocomm txd/rxd leds
* inductor for the video tx power supply, and BFO cap (need to source both).
* More 0.1uf caps around the place as planned.
* Temp sensor in MCU RF enclosure (LM60?)
* Temp sensor on the PCB to measure surface temp
* Current sensor
* Silk screen
* Mounting holes


Whole sensor board...
* Sensor board needs an inductor from the micropsu, and a number of caps.
* Gas
* Geiger
* Accelerometer
* External temp
* Humidity
* UV
* Light level
* Dust/particulate
* Pressure? - do i bother?

Rris
Posts: 66
Joined: Mon 12 Oct 12 2009 9:17 pm

Re: Scorpion Controller Board

Post by Rris » Thu 09 Dec 09 2010 6:15 pm

The only RF shield high enough to take an inductor is BMI-S-207-F. This is 1.747" (44.37mm) x 1.747" (44.37mm) x 0.384" (9.75mm) which is pretty big.

Fotofab also make some, but you need to bend them yourself it appears - they look like just flat stamped out or laser cut then embossed tin. Very expensive really. They also do not allow any visualisation of the parts inside once placed. The smallest of these is 1" (25.4mm) x 1.5" (38.1mm) x 0.5" (12.7mm) Which is about the size of the less high Laird ones.

It might be possible to fit both under the mid sized fotofab shield which is 1.5" (38.1mm) x 2.25" (57.15mm) x 0.5" (12.7mm).

Rris
Posts: 66
Joined: Mon 12 Oct 12 2009 9:17 pm

Re: Scorpion Controller Board

Post by Rris » Thu 09 Dec 09 2010 8:59 pm

Made footprints for the 4020 Inductor footprint, and LM60 temp sensor.

So the GPS and MCU now have isolated supplies with an inductor and large capacitance. The MCU gets C11 which was before an extra cap for the right hand side of the board (since 3.3v was on the left before). The GPS gets an extra 10uF 1206 cap (making it two, plus multiple 100nf's).

Added MCU temp sensor to AD1, board temp sensor to AD2. Both are LM60's (or any SOT-23-3 Analogue).

Removed reset/loader buttons, replaced with 0.1" PTH holes which can be activated with tweezers or any metal object. I'm reluctant to put pins on there after seeing the DragonOSD V1 reading random temperatures from static electricity floating around on the pins.
ScorpionPCBDay4.jpg
ScorpionPCBDay4.jpg (69.62 KiB) Viewed 4513 times

Rris
Posts: 66
Joined: Mon 12 Oct 12 2009 9:17 pm

Re: Scorpion Controller Board

Post by Rris » Mon 13 Dec 13 2010 10:56 am

As a reminder, i need to change the USB host to a vertical port rather than horizontal, this will save some space.

Rris
Posts: 66
Joined: Mon 12 Oct 12 2009 9:17 pm

Re: Scorpion Controller Board

Post by Rris » Mon 07 Feb 07 2011 10:02 am

I'm going to switch the power supplies over to smaller IC's and smaller diodes so as to greatly reduce the footprint on the board.

Rris
Posts: 66
Joined: Mon 12 Oct 12 2009 9:17 pm

Re: Scorpion Controller Board

Post by Rris » Fri 18 Feb 18 2011 7:25 am

I'm now using two LM22676MR vreg's on the board, using a schematic designed in webbench with all the values correct for 5v and 3.3v @ 2.5A. These are quite a bit smaller overall than the old supply circuits.

PCB is now ~76 x 60mm with mounting holes and some space left for the other parts i need to add. This will be smaller than the inside of the balloon's payload bay (since base size is determined by the patch antenna and batteries).

On main board i still need to:
* Large cap for 3.3V in general
* Inductor for the aerocomm (ultra low resistance) and another large cap (another 470uf/6.3v tantal?)
* Aerocomm connector on bottom
* Aerocomm txd/rxd leds
* inductor for the video tx power supply, and large cap
* connector for the video TX
* Current sensor

Whole sensor board...
* Inductor and large capacitance
* Gas
* Geiger
* Accelerometer
* External temp
* Humidity
* UV
* Light level
* Dust/particulate

Daniel Wee
Site Admin
Posts: 2073
Joined: Wed 25 Feb 25 2009 8:00 pm

Re: Scorpion Controller Board

Post by Daniel Wee » Fri 18 Feb 18 2011 9:31 pm

Gotta watch the 300V+ power supply for the Geiger counter. That one is sure to create RFI havoc.

Daniel

Rris
Posts: 66
Joined: Mon 12 Oct 12 2009 9:17 pm

Re: Scorpion Controller Board

Post by Rris » Sat 19 Feb 19 2011 10:11 am

hmm, i'll have to work out some sort of shield for it :)

Daniel Wee
Site Admin
Posts: 2073
Joined: Wed 25 Feb 25 2009 8:00 pm

Re: Scorpion Controller Board

Post by Daniel Wee » Sat 19 Feb 19 2011 11:05 am

Yes - could be tricky though. The ionic discharge triggered by a particle would essentially be a 300V spark. This creates a massive EMI in close proximity. Secondly, the inverter required to produce the 300V also generates a ton of EMI. It's hard to say how much but it would be similar to what you get off the back of a tube TV.

Daniel

Rris
Posts: 66
Joined: Mon 12 Oct 12 2009 9:17 pm

Re: Scorpion Controller Board

Post by Rris » Sat 19 Feb 19 2011 4:05 pm

Hmm, This would only possibly affect the GPS, as the video and aerocomm are both TX.

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