Which boards can i use for this project?

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Leonacn
 
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Which boards can i use for this project?

Post by Leonacn »

Hi Adafruit,

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 don’t run in the same stupid and confusing capable input-voltages again 😊

Thanks a lot in advance out there!!
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adafruit_support_bill
 
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Re: Which boards can i use for this project?

Post by adafruit_support_bill »

The voltage regulators on the Pro Micro (and just about all similar microcontroller boards) are linear regulators. Linear regulators work sort of like a smart resistor to burn off any excess power as heat. Since power is volts times amps, higher voltage and/or higher current draw mean more heat to be dissipated.

So, the maximum voltage rating of the part needs to be taken with a grain of salt. While it might be able to handle 16v at negligible current draw, when you start to load it down with something like an LED display, it will start to get a lot warmer. And excessive heat will eventually kill any IC.

"Buck" type regulators are far more efficient than linear regulators. They work by rapidly switching the input power on and off, then filtering that output to achieve the desired voltage. This wastes much less power as heat. Adding one of these between your 12v supply and the speedometer circuitry would be a good way to go. https://www.adafruit.com/product/4739

We have several options for a 4-digit 7-segment display. The FeatherWing version is designed to plug directly into any of our Feather processors. Of you could connect it to the similarly sized Pro Micro with jumpers.
https://www.adafruit.com/product/3088

We also have a breakout board version that is just slightly larger: https://www.adafruit.com/product/813

Both of these options are available in several different display colors.

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Leonacn
 
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Re: Which boards can i use for this project?

Post by Leonacn »

Okay I think I will go for the buck-type then. Thanks a lot for your explanations and guiding 🙂👍

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