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Old Dec 01, 2012, 09:09 PM
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Originally Posted by Dennis Frie View Post
That's a bad idea, MAX7456 is rated at max 5.25 volt
Just add a little extra capacitor or similar.
Dennis,
You talking something like this ?
Rick
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Old Dec 02, 2012, 01:35 AM
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Oh man, give the guy a break, I think he said he needed to just stay where he was project wise or even cut back? He is a University student, has a job and does all these projects for us and has his own hobbies - he needs some time to actually use his stuff and not get burnt out. Hell he is going to get a break after he gets his job out of school and a family the way he is doing stuff currently.

If stuff is acting wacky, just use a copper condom and that should fix it , it did for you - good for all to know

Bob

Quote:
Originally Posted by RickEis View Post
Dennis,

You were asking for project ideas......

How hard would it be to build something that can check our antennas and something to check how noisy all these other electronics are? Maybe you have built something like that already?

The GoPro was sending the NAZA gps all over the place. I wrapped the GoPro in a copper foil which apparently fixed the problem. But what about all the other electronics? Are they making noise that will cause problems one day?

It would be cool to have something that would detect and or analyze all these things.
It would be a blast to build one if possible?

Rick
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Old Dec 02, 2012, 01:15 PM
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Quote:
Originally Posted by RickEis View Post
Dennis,

You were asking for project ideas......

How hard would it be to build something that can check our antennas and something to check how noisy all these other electronics are? Maybe you have built something like that already?

The GoPro was sending the NAZA gps all over the place. I wrapped the GoPro in a copper foil which apparently fixed the problem. But what about all the other electronics? Are they making noise that will cause problems one day?

It would be cool to have something that would detect and or analyze all these things.
It would be a blast to build one if possible?

Rick
Yup, pretty much what Bob said, as I have been pretty busy lately

But with that being said, HF is not very good as a DIY-projects, unless you are quite experienced. The traces, components etc. is really important.

And then again, have you checked my previous projects? I have already written the software, so you can just get a RFM22B/OpenLRS receiver (will most likely be available from HK dead cheap soon) if you wan't to check for noise in the 433mhz area. It can scan the same band as RF-explorer WSUB1G if you change the input-filters.
http://www.rcgroups.com/forums/showthread.php?t=1617297

It have been used by a few to find noise-sources etc. and was also used to find a bug in the UK UHF firmware (they used another frequency than expected)
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Old Dec 02, 2012, 01:20 PM
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Originally Posted by RickEis View Post
Dennis,
You talking something like this ?
Rick
Just add a normal LC-filter on the output from the UBEC. Should be fine. You can also add a little capacitor on the output from the voltage-divider, that will act as a lowpass-filter and remove the noisy measurements.
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Old Dec 02, 2012, 09:33 PM
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Originally Posted by Dennis Frie View Post

And then again, have you checked my previous projects? I have already written the software, so you can just get a RFM22B/OpenLRS receiver (will most likely be available from HK dead cheap soon) if you wan't to check for noise in the 433mhz area. It can scan the same band as RF-explorer WSUB1G if you change the input-filters.
http://www.rcgroups.com/forums/showthread.php?t=1617297

It have been used by a few to find noise-sources etc. and was also used to find a bug in the UK UHF firmware (they used another frequency than expected)
Wow, very interesting - just a quick look and it appears to be what I was looking for -
Thanks Dennis
Rick
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Old Dec 02, 2012, 09:36 PM
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Quote:
Originally Posted by Dennis Frie View Post
Just add a normal LC-filter on the output from the UBEC. Should be fine. You can also add a little capacitor on the output from the voltage-divider, that will act as a lowpass-filter and remove the noisy measurements.
Thanks
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Old Dec 03, 2012, 04:59 PM
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Just updated PCB with 3.3V LDO regulator for I2C, 2 pads for RAW if needed for other equipment, PPM-input is now connected directly to GND and Vcc (which means that the OSD can be powered directly from the receiver if needed), and minor changes in the layout.

It's an untested design, but I don't mind to make it available if anyone is interested

The gerber-files etc. will be available when I have a "final design" that have been tested
https://www.batchpcb.com/
https://www.batchpcb.com/pcbs/100746

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Old Dec 03, 2012, 06:03 PM
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Hmm...very interesting :0 What else would I need to make it run... chips. etc ..special soldering equipment?
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Old Dec 03, 2012, 06:21 PM
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Hmm...very interesting :0 What else would I need to make it run... chips. etc ..special soldering equipment?
I would recommend some experience with SMD-soldering. The pin-spacing on MAX7456 is quite small.
Take a look at your MAX7456 breakout-board. If you are able to solder all those components - you should be good to go.

If you have never soldered SMD before, this is not the best place to start. It's not exactly a DIY-friendly board, as MAX7456 is not available in larger packages.

I just use a descent soldering-iron and some solder-wick. It works pretty well.
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Old Dec 03, 2012, 06:30 PM
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Could you put together a list and suppliers for the other parts...or what are your thoughts ?
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Old Dec 03, 2012, 06:34 PM
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Could you put together a list and suppliers for the other parts...or what are your thoughts ?
Sure, I'll make a list with needed components later
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Old Dec 03, 2012, 09:53 PM
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Could you put together a list and suppliers for the other parts...or what are your thoughts ?
if you want to practice, i think i have the parts necessary to make a pro mini, so you can see what you are getting into?
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Old Dec 04, 2012, 07:09 AM
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I think this should be the basic BOM...

Necessary components
1 x Atmega328p (farnell 1715486)
1 x MAX7456
1 x 16MHz crystal (farnell 1841946)
1 x 27MHz crystal (farnell 1841955)

0603-size:
2 x 18pF (load caps for 16MHz crystal, should be NP0/C0G)

0805-size:
1 x 100nF (used to AC-couple video-signal input)
2 x 75ohm (input and output impedance of video line)

1206-size
2 x 47uF cap (to AC-couple video-output. Tantalum is fine)

Recommended components

0603-size:
5 x 100nF (decoupling on Atmega328p and MAX7456)

0805-size (0603 is also fine):
3 x 1k (used to pull-up sync-signals to 5-volt)
1 x 10k (used as pull-up on atmega reset-pin)

Voltage-divider
1 x 3k3
1 x 10k

Analog input:
2 x series resistors

Optional components:

For I2C:
SOT-23 3.3V LDO regulator
1 x 1uF capacitor (0603)

For extra decoupling you can use:
2 x 1206 capacitors
4 x 0805 capacitors
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Old Dec 04, 2012, 12:39 PM
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Quote:
Originally Posted by Dennis Frie View Post
I think this should be the basic BOM...

Necessary components
1 x Atmega328p (farnell 1715486)
1 x MAX7456
1 x 16MHz crystal (farnell 1841946)
1 x 27MHz crystal (farnell 1841955)

0603-size:
2 x 18pF (load caps for 16MHz crystal)

0805-size:
1 x 100nF (used to AC-couple video-signal input)
2 x 75ohm (input and output impedance of video line)

1206-size
2 x 47uF cap (to AC-couple video-output)

Recommended components

0603-size:
5 x 100nF (decoupling on Atmega328p and MAX7456)

0805-size (0603 is also fine):
3 x 1k (used to pull-up sync-signals to 5-volt)
1 x 10k (used as pull-up on atmega reset-pin)

Voltage-divider
1 x 3k3
1 x 10k

Analog input:
2 x series resistors

Optional components:

For I2C:
SOT-23 3.3V LDO regulator

2 x 1206 capacitors
4 x 0805 capacitors
dont you need 4 of the 18pf npo caps (2 per crystal)? also that is sot23-3 for the ldo - i think microchip makes them in w/ good specs in 23-3 instead of 23-5 (and the ds wants 1uF+ caps for say the microchip MCP1702T-3302E/CB). this info is just for the newcomers to building smt stuff.

i personally use 1% resistors, 10% caps on my stuff (unless ds states otherwise) and other than the 18pf npo i am assuming x7r for other 0603/0805 caps and the 1206 47uF in tantalum? also might want to list min V requirements for the caps - i haven't looked at the ds for the max chip so I don't know if anything needs a relatively high V tolerance (like the invensense itg3200/mpu3050/mpu6000 and many other in that line, the ds states the charge pump cap 2.2nF needs to be rated @ 50V)

i would also recommend people buying quite a few of the components, especially the 0603 stuff - they are cheap and can easily be blown off the pcb or just plain lost. 0805 and 1206 not so much, but again, the prices are not too bad, w/ the exception of the 47uF tantalum caps @ ~.50 or so each, the other caps/resistors will be much cheaper. last time i bought 1000 1K resistors, 1% i think i paid $3, and that is through mouser

just a couple things you may assume but people new may not know

bob4432/brian
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Old Dec 04, 2012, 12:57 PM
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Originally Posted by bob4432 View Post
dont you need 4 of the 18pf npo caps (2 per crystal)? also that is sot23-3 for the ldo - i think microchip makes them in w/ good specs in 23-3 instead of 23-5 (and the ds wants 1uF+ caps for say the microchip MCP1702T-3302E/CB). this info is just for the newcomers to building smt stuff.

i personally use 1% resistors, 10% caps on my stuff and other than the 18pf npo i am assuming x7r for other 0603/0805 caps and the 1206 47uF in tantalum? also might want to list min V requirements for the caps - i haven't looked at the ds for the max chip so I don't know if anything needs a relatively high V tolerance (like the invensense itg3200/mpu3050/mpu6000 and many other in that line, the ds states the charge pump cap 2.2nF needs to be rated @ 50V)

just a couple things you may assume but people new may not know

bob
Hi Bob
Thanks for your comments, always nice with some feedback. I see some information slipped, I will edit the post

You only need 2 x 18pF capacitors, as MAX7456 have internal load-capacitors. I had the footprints on the first PCB-design and checked that it worked without mounting extra capacitors

The 3,3V ldo regulator is a SOT23-3. I could have picked a SOT23-5, but it shouldn't make any major difference. I will probably use a 1 uF cap on the output, I believe 100 nF is acceptable as well, but you are right, 1 uF is the recommended value.

The resistor and capacitor ratings are not very important for this purpose, pretty much all components can be low rating (sure, C0G/NP0 at 18pF caps is a good idea) , but the rest of the components doesn't really matter. It's all running at 5-volt which shouldn't be any problem at all.
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