Glitch busted!

Waggly tails
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jmendoza
Posts: 70
Joined: 18 Feb 2018, 23:07

Glitch busted!

Post by jmendoza » 17 Sep 2018, 21:51

I want to thank Martin and others here as well for their assistance.
I accidentally found that an old Rand LR-3 I was using to test my recoders had a 100 ohm resistor across the motor terminals. It did not glitch at all so I tried the same with my Tobes and viola! The glitch that had been plaguing me went away :D.

Tobe
Posts: 70
Joined: 16 Feb 2018, 06:19

Re: Glitch busted!

Post by Tobe » 18 Sep 2018, 05:55

This reflects in some way what was discussed in my work to ge a "Dual Pack"working properly at high rates. In that occasion the heat of the motors was a major issue an if I remembered right I blamed it to Eddy" currents when quickly inverting polarity and the issue was at the time partially solved with resistor across the poles of the motor.
Low rpm motors are less affected by critical Eddy currents and allows higher Hz but that would require a complete redesign of the GG-Tobe that relies as concept on high rpm and high reduction gearbox to reduce/optimize weight and current draw.
In that occasion I run some numbers in accordance with Lenz and Faradays law to get a time factor and see if they can be suppressed. The tendency of Eddy currents to oppose changes in the direction of the magnetic cause energy to be lost. More accurately, Eddy currents transform more useful forms of energy, such as kinetic energy, into heat/spark, which is generally much less useful! Somewhere around 12 Hz was what I came up with for this motor before a critical point where reached concerning the Eddy currents before they become dominant and we get losses/disturbances. Here it has to be said that the recoder runs slightly lower, roughly 10 Hz but could in some occasion top at a higher Hz number not least due of a positive spring force that accelerate the movement. I never thought about to relate this to the glitches but would make sense.

Twitcher
Posts: 19
Joined: 16 Feb 2018, 12:17

Re: Glitch busted!

Post by Twitcher » 13 Nov 2018, 20:45

SpikeS alerted me to this "fix" when it first appeared but I've only just got round to trying it.
Despite my various attempts at suppression, my home-brewed actuators (and all the others!) have always suffered from an occasional twitch. The R100 resistor appears to have done the trick. Thanks Jay - good job!
I've just completed a new John Ralph "Wagtail" equipped with another homemade GG actuator. It's a fast model and it'll be all the better for this mod.

David

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