I have a Arduino MEGA2560 clone, 5pcs of standard size servo motor (model MG996R) and 2 pcs of micro sized servo motors (model 9G), which I have to supply with DC power. And because the micro Servo 9G can use only 6V and the Arduino and standard Servos can use 7.2V, I'm quite confused about power supply of the whole board.
Here's the table of operating voltages:
Arduino mega2560 (recommended): 7-12VDC
Arduino mega2560 (limited): 6-20VDC
Servo MG996R: 4.8-7.2VDC (current at 6V: 0.5-0.9mA, stall: 2.5A)
Micro Servo 9G: 4.8-6VDC (current at 6V: 0.25A, stall: 0.96A)
I already have 4 new toroid transformers, which I attempt to use in this project, but still don't know what schematic should I use. I have:
2pcs primary: 230V secondary: 12V [S=30VA]
and
2pcs primary: 230V secondary: 11.8V [S=50VA]
The whole thing got stuck for me, because I don't know what schematic should I use to transform 12VAC or 11.8VAC to 7.2VDC AND is there a possibility to make from 1 toroid transformer 7.2V and 6V? If so, what schematic would be proper for this?
And in case if anything helps, I do have exact this DC-DC modul, which I can use at this project.
Would be really gratefull to whoever would help.
Best Answer
If full-wave rectify your 12V transformer and filter it you'll get around 15VDC. You could use 3 pieces of your DC-DC converter to give you 5.5V at 5A (2 servo) + 5A (2 servo) + 4.5A (1 servo and 2 small servo) and use an LM7809 to preregulate for the Arduino.
The total consumption is more than 80W peak, so you could also split the supply using 2x 50VA transformers.
So- two 50VA transformers, two bridge rectifiers, two large filter capacitors, 3 DC-DC converters, and one LM7809 (with input and output capacitors). Using 4 DC-DC converters would allow you to split the load between the transformers more evenly, but probably okay as is. Capacitor value- maybe 22000uF/25V for about 1.5V ripple p-p.