cosplaying_bunny
Hi all!
i've been a bit busy with practicing my pcb design skills, and designed a 7,5A servo PSU.
specs:
7,5A max out
8-18VDC in power in (ideal for a car batery
9-15V recommended)
power supply out: 5,05V (@8V in)
power supply out: 5,21V (@12Vin)
power supply out: 5,24V (@15Vin)
pcb dimensions: 2 inch x 1 inch
needed parts list:
1x 5k6 resistor
1x 33k resistor
1x 22k resistor
1x 1k resistor
1x 100nf cap
2x tip47 transistors (or other NPN transistors)
1x 2sc5200 transistor (or any other NPN one with a high current capability~)
1x 6,2V zener diode
a way to make your pcb (be it etched, on a expirimental pcb or another way)
a heatsink (standard 60w cpu heatsink should work if it has a solid aluminium base large enough to fit all 3 transistors)
and of course your servos!
optional parts:
screw terminals for on your pcb.
approx costs of the parts (excl pcb and servos): around $10
i hope this is usefull for the community to make powerfull power supplies
here is the schematic:
and how to wire it up:
the pcb with it's components:
and finally, the pcb itself (non-mirrored!) on a non-scale:
important!: i am not responsible for design errors or anything, i just want others to know how they need to make this sort of stuff!
maybe for other users: a soldering practice, something to be proud of because they made it themselfs?
and i honestly don't know what a LDO is.. :o
____
edit, i searched it up, and found out that the 78xx and 79xx are LDO's
which i have a 10A schematic laying around of it.
LDO is a low drop out regulator, basically it has less losses and produces less heat etc. One of them, a couple of capacitors and some resistors and you're done. Google it and you'll see schematics I'm sure.
and made a pcb for it.
7,5A max, 6V out based on a 7806 LDO regulator and a 2sc5200 transistor
same pcb dimensions, 1 inch x 2 inch~
this time it's a 20A one (maybe even more)
it is based on a lm7805 (or lm7806 for 6V output) and 2 TIP36C transistors.
the input voltage is: 9-14V, and the output is 5V (if you use a lm7805) with 20A
note: if you want to use this psu in your robot, be sure your battery or power supply can handle at least ~30A of continous load (when fully used)
there are a few reasons why i choose this design:
you can easily upgrade it from 5V to 6V out, simply by switching the volt regulator,
you can easile add more transistors for greater power
also: it is cheaper to upgrade it, because 1084 ic's aren't that cheap, and one TIP36C can handle more than 10A out continous (equals 2 1084ic's)
there are also a few things why you shouldn't use this:
when you need a compact power supply (it is a bit large)
or when you have a low input volt of lower than 9V with less than 30A out continous.
note: this is really only usefull for advanced robots with ALOT of servos (say more than 30) and too high input voltage or for robots which have current-consuming servos (like digital servos)
use at your own risk and USE FUSES in case of short circuit or what ever, oh and also use >10mm2 for the wiring because of the current draw.
pcb design in the zip