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I am playing / built a mini robot of sorts - made from a 12v dc NUC slimline PC, 2x 7.5v 500ma servos, 2x 7.5vdc IP cameras , a 3vdc laser pointer and an arduino. I've got 4 different power supplies powering it (one for the NUC, one for the servos and one each for the IP cameras). The arduino takes it power from the USB port on the NUC.

I am a software developer and not an electrical engineer, hence the question:

Would it be possible (or a good idea) to buy some dc-dc stepdown converters (1x 12v to 7.5 for the servos and cameras, and 1x12v to 3v for the laser) , wire these on parallel to the 12 supply and power lot from the one supply?

I'd need to make sure the 12v supply has enough capacity to power them all/get a bigger one. Although these are cheap (as are the converters) so would be willing to get the kit if it means one power supply for the lot.

Possible? Or oversimplified or plain dangerous?

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    \$\begingroup\$ Draw a schematic or block diagram. \$\endgroup\$ – winny Dec 17 '17 at 8:54
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It is feasible , but even cheaper if you can use any PC ATX supply. (Free surplus)

5V cams are avail here http://www.endoacustica.com/ip-micro-camera-wifi-streaming-kit.htm

3V LDO or perhaps 3.3V from PC PS will work on laser etc.

Molex to USB breakout cable is easy to make for 5V and 12V. One just needs a jumper to gnd for Pwr On signal. (Easy to find)

If you supply servo specs/datasheet, there may be simple sol’n for this.

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  • \$\begingroup\$ Great idea. I've considered an atx PSU although ruled it out for a few reasons, mainly the solution was be noisy (the nuc is silent - fanless and ssd drive) and I'd not want to introduce a fan . The other issue is the servos are 6v min and 7.5v gives the best (fastest) rotation, so I'd still need a conversion there. If I was buying item, I'd get low voltage cameras , however, everything has been free so far (surplus from work / already owned by me) . The IP cameras also have a motion detection feature I'm going to utilise \$\endgroup\$ – Jack Dec 17 '17 at 13:37
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That sound reasonable.

You would need to make a power budget for the supply, by adding all the powers consumed by each individual components at worst case. Multiply each by the efficiency of the DC-DC converters (70% is a good start if you don't know it yet), and add a margin (25% to 50% for example).

If the NUC share the same power supply, it could have issue with the noise generated by the step down converters. Depending of the quality of those, you may have to add bypass capacitors. You could use 2 separated DC-DC converters for the servos and the IP camera for the same reason.

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  • \$\begingroup\$ This sounds good. The NUC would share the 12v (so the NUC and the DC-DC converters would all be wired in parallel to the supply). I'd imagine the converters are low quality (cheap Chinese things). I've just had a quick read up on bypass capacitors (decoupling capacitor) although have no idea what would be an appropriate choice in this situation. Could you please make a suggestion, or, point me to a resource so I can work it out myself? \$\endgroup\$ – Jack Dec 17 '17 at 13:50

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