i have connected to my controller several sensors(2 IR and one Ping) and a two servos. I notice that when the controller is powered by USB and the servo is moving, the ping can not get a reading. When powered by an external power source, it works much better, but occasionally does exhibit the issue where the ping can not get a reading.
Using a MM, i observed the following:
I notice that while the servo is moving, the current draw is anywhere between 30-145ma.
If no external power source is used, the voltage drop across the Ping is 4.53 on initialization. As soon as the servo is moved it drops to around ~4.38-4.45 and remains in that range.
When an external power source is used, the voltage is ~4.67 on initialization and fluctuates between 4.64-4.67 while servo is moving.
More power seems to be drawn when the servo reaches the far end of its movement range
My question is..what is the best way to ensure the sensors/components receive a constant voltage? Is powering by say a 7.2v source and putting a voltage regulator infront of the Ping the solution here?
For example, the arduino UNO has a voltage regulator that will drop about 2v. That means to get 5v out you will need to feed it at least 7v. You are seeing voltage drops when using USB because the power you are supplying is insufficient to manage 5v and deliver all the current that is required. From what I have read, the less expensive ultrasonic sensors don’t like much less than 5v.
Make use of the 7.2v battery and let the vreg on the microcontroller board supply the current.
Thank you. I have a system that is using both a Gadgeteer Cerbuino board as well as an Arduino Duemilanove. In this case the sensors and servo are connected to the Gadgeteer board. As you mentioned, when i use a 7.2v power supply, things work much better.
I also am seeing an issue with trying to power a Foscam FI9821Wv2 camera from the 5v output of a Sabertooth 2x12 controller. The power supply i’m using for the sabertooth 9.6v. Rather than use the 5v output of the sabertooth (since that is not working), i ran wires from where the battery is connected to the Sabertooth to a 5v regulator then to the Foscam. Still no go. The camera works fine when connected to 5v wall jack dc adapter…just can’t get it going from a battery source.
