Octopod servo controller

Discussions regarding building a walking robot at home. Most of the robots participating at Robo-One competitions are custom fabricated.
17 postsPage 2 of 21, 2
17 postsPage 2 of 21, 2

Post by robots42 » Tue Aug 12, 2008 6:20 pm

Post by robots42
Tue Aug 12, 2008 6:20 pm

Hi
First of all, originally a BEC was a Battery Eliminator Circuit and eliminated the need for separate radio and servo batteries, I think the terminology is now a little muddled, but BECs supplied regulated voltage for the electronics while motors ran from raw battery voltage.

The amainhobbies product is a high power regulator not a BEC.

According to one Hitec rep, Hitec servos don't smoke until run on over 12v and many servos now are spec'ed for more than 6v.
Switching regulators are a pain, and sometimes don't like supplying motors.

The problem with running servos on higher voltages is not that the control electronics will blow up but that the motor will take more current which may be too much for the H-bridge transistors even on light loads. Basically if your servos are not able to carry your robot you need bigger servos or less weight or a different leg design.

The easiest way of dropping the voltage is a high current Si diode, or two, each diode will drop ~0.7v on no load. Two diodes in series will drop a 2 cell LiPo battery down to 6v.

David
Hi
First of all, originally a BEC was a Battery Eliminator Circuit and eliminated the need for separate radio and servo batteries, I think the terminology is now a little muddled, but BECs supplied regulated voltage for the electronics while motors ran from raw battery voltage.

The amainhobbies product is a high power regulator not a BEC.

According to one Hitec rep, Hitec servos don't smoke until run on over 12v and many servos now are spec'ed for more than 6v.
Switching regulators are a pain, and sometimes don't like supplying motors.

The problem with running servos on higher voltages is not that the control electronics will blow up but that the motor will take more current which may be too much for the H-bridge transistors even on light loads. Basically if your servos are not able to carry your robot you need bigger servos or less weight or a different leg design.

The easiest way of dropping the voltage is a high current Si diode, or two, each diode will drop ~0.7v on no load. Two diodes in series will drop a 2 cell LiPo battery down to 6v.

David
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Post by cyberdead » Mon Sep 22, 2008 1:07 pm

Post by cyberdead
Mon Sep 22, 2008 1:07 pm

Thanks for reply, i havent read the for a while so there happened many things. Now about the power supply. I use a simple 5cell NimH hobby battery, which has 6v of voltage. It's not to good but enough for testing. But, i heard many things about the so called fuel cells. Is there anyone who knows more about it? I would like to know, is there any fuel cell with the size of 5cmx5cmx5cm approximately. and with the weight under 120g, with voltage of 6v?
Thanks for reply, i havent read the for a while so there happened many things. Now about the power supply. I use a simple 5cell NimH hobby battery, which has 6v of voltage. It's not to good but enough for testing. But, i heard many things about the so called fuel cells. Is there anyone who knows more about it? I would like to know, is there any fuel cell with the size of 5cmx5cmx5cm approximately. and with the weight under 120g, with voltage of 6v?
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