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General Misc => Misc => Topic started by: Pianigro on December 27, 2011, 04:01:47 AM

Title: Lab Power Supply for Axon II
Post by: Pianigro on December 27, 2011, 04:01:47 AM

Hi,

Currently I am using a 6V 1.3AH batter to power my Axon robot, however while programming the axon I could do with a lab power supply, so I purchased a AC adaptor power supply (input 100-240V ~ 50/60Hz, Output 6V 1.5A). When I connect to my Axon II, it turns on the off, on then off. The output voltage of the power supply is constant, however the amps oscillate from 1.2 to 0 - not sure why. Has anyone had this problem and can I rig a capacitor or something to stabilise my power supply?

Thanks Paolo

Title: Re: Lab Power Supply for Axon II
Post by: Cristi_Neagu on December 27, 2011, 04:23:07 AM

Sounds like there's a short somewhere. And did you measure the voltage yourself, or does it have an indicator of some sort?

Title: Re: Lab Power Supply for Axon II
Post by: Pianigro on December 27, 2011, 04:30:35 AM

I measured the voltage myself, I have had similar issued with smaller power supplies (ones used to charge mobile phones), just thought I needed one with more amps. The thing I can not understand is the oscillations. It is unregulated, would the output volts remain constant and the amps vary? 

Title: Re: Lab Power Supply for Axon II
Post by: Gertlex on December 27, 2011, 10:01:09 AM

What happens if you wire it to a breadboard and an LED+resistor?

Title: Re: Lab Power Supply for Axon II
Post by: Admin on December 27, 2011, 08:23:27 PM

What you have is current over draw.

While your battery can likely supply 8A to 16A, your power supply can only do 1.5A. If you draw more than that, the voltage will drop, causing your microcontroller to shut down. When your mcu is down, current drops so voltage is restored, causing your mcu to turn back on again. This causes the oscillation you see.

A single HS-311 servo can draw 1.5A under high torque. Are you powering a servo?

Title: Re: Lab Power Supply for Axon II
Post by: Soeren on December 28, 2011, 01:40:35 AM

Hi,

Quote from: Pianigro on December 27, 2011, 04:01:47 AM

[...] AC adaptor power supply (input 100-240V ~ 50/60Hz, Output 6V 1.5A).

That's a switch mode supply.

Quote from: Pianigro on December 27, 2011, 04:01:47 AM

[---] can I rig a capacitor or something to stabilise my power supply?

You could try a small value resistor (5..10 Ohm max) and a cap of 1000µF to 4700µF. This would buffer the peak currents that probably cause supply brown-outs as is.

Title: Re: Lab Power Supply for Axon II
Post by: Pianigro on December 29, 2011, 05:24:25 PM

Thanks for all the comments, sounds like I am drawing too much power, I am powering 14 servos.

I have looked at other posts on power supplies and may look at converting a PC power supply I have lying around in my garage.

Paolo