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[Crossie]

Hello All,
                I'd like advice from folk who understand the workings of servos. I want to prevent one particular control moving when another/ different control is in a particular position. I can rig a micro switch so that at this position it breaks contact to the second servo, but which cable should go through the switch.......... the pos.+ the neg.- or the signal? Does it even matter?

                                                           Trevor

[wombat]

If you must do it, I would suggest breaking the signal line - break either the power or ground and you risk damaging the electronics. Breaking the signal should just stop the servo dead. I would suggest putting in a pull down resistor on the signal input 10K or so to ground so the servo does not glitch from noise.

Wom

[derekwarner]

This is essentially how real naval vessels attain non pointing or non firing zones [via their fire control computers systems] for gun mounts or missile launchers

Just think of FWD mounted naval gun mount which has an arc of fire between two points...say 210 degrees included angle, however the Jackstaff at the bow would be in this arc

So you could set the servo cam plate with a continuous cut out to ~5 degrees either side of midships, so when the micro switch roller is within the cam plate cut-out area, the firing circuit [of the second servo] is interrupted

The above is only an example as they tend not to shoot with the Jackstaff raised   ...& I bow to the knowledge of others with respect to adding Blackart thingies to the circuit..... Derek

[malcolmfrary]

What Wom said- just add that it is never a good idea to interrupt the neg wiring as all sorts of electrical silliness can happen.  If the pos to a servo is interrupted, there is always the probability that the servo will twitch when power is reconnected.  No doubt someone will come up with a PIC chip circuit and program, but a cam and microswitch should be just fine.

[Crossie]

 Thank you Wombat, and Malcolm, pretty much what I suspected/ had a vague memory of reading somewhere, though I was unaware of the need or  benefit of a resistor

 Similar requirement Derek, though in this case to prevent hydroplanes moving when they're folded and as I have already built and installed the mechanism I cannot modify it to incorporate an automatic mechanical dis-connect. Next model maybe.

   Thanks,
                    Trevor

[wombat]

If you break the positive and the signal is driven high you risk causing a latch-up condition which could screw up the radio and destroy or damage the servo electronics

Wom

[Calimero]

Get a flexible TX that allows you to solve this on the TX end ?


Electronics nowadays let us have much more control (and much finer granularity)

[Crossie]

 
 Thanks Calimero, but cannot it be done at Tx end because I'm just using olde worlde non programmable gear,

              Trevor