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 From:  Chris (CHRISSS)   2 Dec 2015 22:53 
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40898.471 
Before I properly design my PCB I'm going to try and make a unit that works with a 18650 rechargeable lithium ion battery instead of AAs. I should be able to rip some out of an old laptop battery if they still work.

I haven't got many 3.3V boost thingies (needed for the temp sensor) for my current setup and they're not that cheap. Should be cheaper to use a zener diode/something else to drop the 4.2V for the RF24 radio.
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 From:  Chris (CHRISSS)   2 Dec 2015 22:57 
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40898.472 
12 of them in this battery :O I hope they work still.
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 From:  Chris (CHRISSS)   2 Dec 2015 23:00 
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40898.473 
And assuming they're genuine they're all Panasonic ones so should be decent quality.
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 From:  Chris (CHRISSS)   8 Dec 2015 00:49 
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40898.474 
Surprisingly that worked. With a normal diode, not a zener. Used the forward voltage of the diode to drop the Li-Ion voltage down to the voltage the radio works at. No voltage regulators needed now, and the DS18B20 temp sensor will work at all the voltages. I'll just have to be careful not to short circuit anything and blow up any batteries.
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 From:  ANT_THOMAS    8 Dec 2015 11:02 
 To:  Chris (CHRISSS)      475 of 542 
40898.475 In reply to 40898.474 
Do you need to be careful with Li-Ion batteries not discharging fully?
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 From:  Chris (CHRISSS)   8 Dec 2015 11:36 
 To:  ANT_THOMAS       476 of 542 
40898.476 In reply to 40898.475 
Yes, looks like it. Just looking it up and they shouldn't be discharged to under 2.4V. All the cells in the laptop battery are 2.2-2.3V so maybe I shouldn't be using them. The one I charged didn't explode though.
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 From:  ANT_THOMAS    8 Dec 2015 11:39 
 To:  Chris (CHRISSS)      477 of 542 
40898.477 In reply to 40898.476 
Do you have a 18650 battery charger?
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 From:  Chris (CHRISSS)   8 Dec 2015 12:17 
 To:  ANT_THOMAS       478 of 542 
40898.478 In reply to 40898.477 
Yes, just got one for my bike lights.
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 From:  Chris (CHRISSS)   9 Dec 2015 22:06 
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40898.479 
My !!/really exciting/!! Atmega 328p programming board.

It's got the 16MHz crystal and caps so I can program my chips to run at 8MHz off the internal clock before sticking them in my temp sensors (only have 1 so far though).
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 From:  Chris (CHRISSS)   9 Dec 2015 22:53 
 To:  Chris (CHRISSS)      480 of 542 
40898.480 In reply to 40898.479 
Forgot to upload the picture.
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 From:  ANT_THOMAS    9 Dec 2015 23:39 
 To:  Chris (CHRISSS)      481 of 542 
40898.481 In reply to 40898.479 
I've got a couple of 328ps but couldn't get them to work. Need to try again.
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 From:  Chris (CHRISSS)   9 Dec 2015 23:45 
 To:  ANT_THOMAS       482 of 542 
40898.482 In reply to 40898.481 
They're pretty easy to get working. Everything on that board will get it detected by AVRdude. You do need a USBasp to program it or upload a bootloader if it doesn't come with one.
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 From:  Chris (CHRISSS)   9 Dec 2015 23:51 
 To:  Chris (CHRISSS)      483 of 542 
40898.483 In reply to 40898.482 
But it should have have some caps and resistors and other bits to properly connect it all up.
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 From:  ANT_THOMAS    10 Dec 2015 10:36 
 To:  Chris (CHRISSS)      484 of 542 
40898.484 In reply to 40898.482 
I think I've got some of the correct caps and a ceramic resonator but couldn't get it working last time.

Still cheaper to buy an Arduino nano though!

Maybe it's cheaper to remove a load of the voltage regulator bits off a pro mini.
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 From:  Chris (CHRISSS)   10 Dec 2015 11:15 
 To:  ANT_THOMAS       485 of 542 
40898.485 In reply to 40898.484 
Really? Cheaper to buy a fully assembled board than a single chip? How much do you buy nanos for? My 10 Atmegas cost £20 so £2 each.

I did try disconnecting the voltage regulator and power LED from a mini but couldn't get the power consumption down far enough. Much easier with the DIP chips if you want to go low power.
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 From:  ANT_THOMAS    10 Dec 2015 11:32 
 To:  Chris (CHRISSS)      486 of 542 
40898.486 In reply to 40898.485 
I bought 5 Nanos for £9.57 early this year. £1.91 each.

I think if low power really is essential then the chip is the way to go.
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 From:  ANT_THOMAS    10 Dec 2015 11:34 
 To:  Chris (CHRISSS)      487 of 542 
40898.487 In reply to 40898.485 
Looks like you can get 10x nanos for ~£16 now.

Possibly even cheaper if you searched a bit harder - http://www.ebay.co.uk/itm/181880011056
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 From:  ANT_THOMAS    10 Dec 2015 11:35 
 To:  Chris (CHRISSS)      488 of 542 
40898.488 In reply to 40898.485 
Just found 10 pro minis for under a tenner.

http://www.ebay.co.uk/itm/201419551076
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 From:  Chris (CHRISSS)   10 Dec 2015 11:56 
 To:  ANT_THOMAS       489 of 542 
40898.489 In reply to 40898.487 
Wow, that's crazy cheap. How much do the official ones cost compared to that?

Cheapest I can find the chips on their own is about £1 each. No caps or crystals with that though. My other ones came with all that sfuff but I don't use them, and a DIP socket and reset button.
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 From:  ANT_THOMAS    10 Dec 2015 11:59 
 To:  Chris (CHRISSS)      490 of 542 
40898.490 In reply to 40898.489 
They're so cheap I pretty much see them as disposable now.

I might see what sort of power a pro mini uses with regulator and all LEDs removed. No USB chip to consume energy either.
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