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By Leonacn
#235972
Hi Sparkfun, I am new in this electronic game, but I have designed a new digital speedometer for my gokart (a really tiny one) from the ground up. For this I needed a small microcontroller, and a colleague happened to have 2 Arduino pro micros (comes from eBay so may be clones), which I bought. Now I have a 12V motorcycle battery on my gokart, which gives 13,85v at MAX charged, so I need a board which can handle that supply voltage, and yet be at the max form factor of a Pro micro/mini WITH usb. When supplying the Pro Micros I got, from this battery on the bread-board, they simply died individually, in matter of seconds. When looking up the LDO on the board, the datasheet said 10V max for one of them, and 12v for the other, but confusingly, a datasheet from sparkfun.com said 16V max ?!? So my question to you is, which boards can I buy from you, which match these criteria ?? -the only thing the board should supply, is a 4-digit, 7-segment, red colored display (TM1637) which draws 80mA at max operating mode. Can you or someone please help me list the possible boards, and will happily buy these, as long as I do not run in the same stupid and confusing capable input-voltages again! Thanks a lot in advance out there!!Image
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By paulvha
#235982
it does not seem to be a matter of "what board", but more the power supply. Often the power from a motorcycle (and even some cars) is NOT a stable voltage but has a lot of noise (read high-frequency spikes) associated with it. The best to do is to reduce the power down to 5V with a 7805 regulator. Look on Internet as there are many examples.
By jremington
#235987
so I need a board which can handle that supply voltage
No, you just need a decent voltage regulator that can handle the input voltage, and supply the current required by the entire project.

I recommend a 5V switching (buck) regulator module as they waste far less power and handle much higher input voltages (typically 35-40V), than a linear regulator like the 7805 .

Power everything from that 5V regulated output. You can apply 5V from an external regulator to the Arduino 5V pin.
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By Leonacn
#236005
Thank you very much for the good suggestions and explanations! I do not have room for a buck converter within my electrical circuit. I think I will go with the regulator (LDO) suggested - however, not the 7805, but 7815 (same family and package size (To-220 3-pin)). I just need to calculate or/and test the temperature of the case/heat-zink for the LDO, since it is close to other cables, but else I could work that out 🙂
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