I'm using some Hitec 7950's in a robotics application with arduinos. The digital servos in general will not release their last position when the signal stops - they will either hold it or return to a "fail-safe" position. This is not necessarily desirable, and so I've added a logic level mosfet driven by one of the Arduino pins to switch off/on power to the servos completely .
This works but one of the servos died completely after about 5 minutes of testing. No warmth or anything like that, just went dead. I somewhat imagine that spikes from the switching may have killed something in the electronics of the servo. The mosfet circuit is still fine and will run other servos & motors.
I already had a kick-back diode across the servo power lines, so now I'm thinking a capacitor might be useful. But I'm not sure of the best place for it. This morning I added a 47uF cap to the Arduino pin to soften the rise to +5 on the mosfet. The alternative would be I guess to put the cap across the servo power leads, parallel to the diode. I'll find out when I get home tonight if this thing survived, it will be running on its own all day to test:)
Just wondered if there are any thoughts about this, whether the cap is a good idea, where a cap is best placed, what size makes sense, other ideas of how the 7950 servo might have died... Thanks!
-Mark M.
http://www.markmalmberg.com