0
\$\begingroup\$

I have 4 Tower Pro MicroServo 9g SG90 I want to power with a battery. This is the datasheet I found online.

I have a small breadboard and some resistors laying around (220, 1k, 10k), and a 9V battery.

I hooked up the battery leads on the power rail of the breadboard, and added my 4 servos in there, and they turned on and rotated properly when I issued commands from my Arduino board. The thing is that AFAIK it operates on 4.8V-6V from what I have read.

I did a voltage divider using some of the resistors I had and I could output 5V when tested with my multimeter, but the servos didn't work (probably because low current).

So my question is, can I power my 4 servos with a 9V battery? Should I add some resistors before? Bear in mind I am new to electronics.

\$\endgroup\$
2
  • 1
    \$\begingroup\$ You would be far better using 4 AAs to get 6v. \$\endgroup\$
    – HandyHowie
    Commented Feb 15, 2019 at 10:56
  • \$\begingroup\$ You cannot use a voltage divider with fixed resistors for a varying load. Voltage dividers which shelf-adjust to achieve the same output voltage as the load varies are called linear voltage regulators. Like other voltage dividers they are horribly wasteful for this use and thus a terrible idea, but they do exist. \$\endgroup\$
    – Chris Stratton
    Commented Feb 15, 2019 at 16:31

1 Answer 1

Reset to default
1
\$\begingroup\$

9V batteries can't supply high currents. If you connected 4 servos in parallel to one battery, the voltage probably dropped far enough to be safe for the control circuits in the servos.

You need around 6V to operate your servos, and you need more current (and capacity.)

The solution is to use 4 batteries in series that provide about 1.5V. Servos aren't terribly picky, so it's not a problem if the voltage varies a bit.

You could use AA batteries, or C, or D. All will give you enough current and capacity to be useful.

You can use alkaline batteries, or rechargeable NiMH. Or a lithium ion battery pack with appropriate charger.

Your voltage divider didn't work because it also reduces the current available to the servos. Your divider lowered the voltage to the servo, but because of the resistance of the divider there wasn't enough current to the servos for them to operate.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.