Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: sim on June 15, 2007, 06:28:34 PM

Title: $50 robot - power problem
Post by: sim on June 15, 2007, 06:28:34 PM
Hi there. First of all, I'm a newbie - sorry if my question seems stupid or something... ;)

I've soldered together the PCB and programmed it with a short servo & LED test. The diode worked ok, but the servo wouldn't move. After figuring out it wasn't a software problem (2 hours of trying different pulse durations, damn... ;) ), I tried checking the voltage, and on the servo pins it was around 1,7 V... On the sensor pins it was ok, slightly above 6 V (I power the robot with 4 AA batteries). I decided to solve the problem the hard way and plugged another 4 AA pack into one of the remaining servo pin sets. It worked, but that's a solution I'd hardly call elegant...

So - any other suggestions how I could get the servo to move? Will replacing the original 4 AA pack with 6 AA work? What would happen if I altered the voltage regulator connection (the tutorial says that servos are powered by unregulated input, while regulated output goes to the microcontroller) - could I simply remove the connection between the regulator input and the servos, and power both the servos and the microcontroller from the regulator output?

Again, sorry if this seems dumb - I suppose I could find the answer myself if I remembered my physics lessons, but junior high was a long time ago... ;)
Title: Re: $50 robot - power problem
Post by: ed1380 on June 16, 2007, 06:21:53 AM
Quote
and on the servo pins it was around 1,7 V
which pin? the signal one or the power.

servos will fry if you give them over 6 volts so no 6 AA batteries
Title: Re: $50 robot - power problem
Post by: Admin on June 16, 2007, 05:15:17 PM
Quote
and on the servo pins it was around 1,7 V... On the sensor pins it was ok, slightly above 6 V
Check your wiring.

The servo power pins should be directly connected to your 6V battery (giving 6V), and the sensor power pins should be directly connected to the output of the voltage regulator (giving 5V).