15Jun/106
New board build
I had a chance to etch and test my first board with the new design. The board itself seems to be working fine, though I haven't got a radio module or GPS on it at this stage - they're still in the mail on their way to me.
I tired dyeing the board using some permanent markers, which did not work so well. Next I'll be trying red fabric dye, which from what I can tell should have better results.
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- Design printed
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- Board scoured and cleaned
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- Toner transfer using an iron
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- Board submerged in hot water
The cost per board works out to around the $100 (AUD) mark:
- PCB substrate: ~$1
- ATMega328P: $5
- LM3940: $1.50
- Temp sensor: $5
- Passives: ~$1
- FSA03 GPS module: $60
- NTX2 25mW Module: $30
Total: ~$103.50
Edit: The fabric dye worked a treat!
June 16th, 2010 - 03:27
hi, i think i have read every inch of your website the last weeks. But i dont get it, why go through such an effort, if you can just use batchPCB like you did before? I ordered my own flightcomputerversion last week. To be fair, i have to add that its more than cool that you can etch stuff at home! Though i think you could almost have this comercially produced, if you would add a GRPS module too.. that would be a very nice complete kit.
Another Q: how the ** can i get my hands on a NTX2?! i rГ©ally cannot find one in supply anywhere.
And, how do you think your icom 706 differs from the old 409a? which would you recommend?
June 16th, 2010 - 11:00
Hi Tim,
Having my boards produced with BatchPCB is good, though theres a substantial lead time, which is annoyingly long given that my boards are sent from Colorado to China, back to Colorado, then to Australia lead time can easily be over a month!
If I etch the boards at home, I can do them in batches of 4 or more the lead time is only an hour or so if I make a mistake, I can easily do it over.
I dont use GPRS/GSM on my boards because mobile coverage is very patchy where my balloons go its unlikely that the payload would have coverage when it came back down though if you live in an area with good coverage like the UK, GSM is a good option as a backup recovery device (questionable legalities etc aside).
I get my NTX2 modules from RFMA (www.rfma.com.au). If youre not in Australia, youll probably need to find a local stockist, or purchase the modules from Radiometrix directly let me know if youre still having troubles.
The 706 is obviously much newer than the 409a it supports nice things like Computer Assisted Tuning (useful for when the radio is connected to the carputer), and is overall more sensitive than the 409a. That said, its also more expensive if you want something cheap to get started, the 409a is a good starting point.
Let me know if you have a website for your own project!
June 16th, 2010 - 22:51
Thanks for the info. I am actually planning on setting up my own website from something like WordPress too. Since i have 0 (zero) RF knowledge, i have no idea how that works. Though i managed to get the SSB software working, and i loved it. I have actually just this morning been in contact with a retailer that sells ntx2 for €17 a piece (!) ánd has then in stock, so i bought two. I think i will buy the 706, itll probably keep its value anyway. I bought two sperachutes too (sorry, ideas are better stolen than made up yourself).
I will fly in about two months from EU mainland. GSM modules are easier with legality than RF. In UK the 25mW NTX2 isnt allowed.
Q: why didnt you choose for a >>>>434MHz transmitter? They can travel further, right?
Q: how did you design the Yagi antenna? how did you came up with the size, or did you just go for maximum largeness.
June 16th, 2010 - 22:54
oh yeah: why does every HABer use such crappy cameras! Why dont we just a lightweight DSLR with a pancakesize(light) wideangle? I know that could run into $400, but its not like the rest of our equipment is cheap, so why save on cameras?
June 16th, 2010 - 22:56
Q4: what transmitting antennas are you using?
June 20th, 2010 - 17:51
Hi Terry & Tim
@Tim: If 433.920 Mhz isnt legal in the UK, look for the Radiometrix TX2H ( http://www.farnell.com) a 25 mW module. Its a wideband fm transmitter so you have to change the resistor bridge.