I'm looking for a means to slow down mechanical retract servos. I understand certain TX's have this functionality (e.g., JR X9303, FU 12FGA, 10CAP?) but I'm flying with a DX7 which I don't think has this ability (haven't really looked yet).

What's the recommended gadget to accomplish this?

Thanks, David.

i think servo city has a gadget that would fit your need. i've seen one somewhere, i just have to think a moment.

Thanks David.

A web search gave me the following hit:

http://www.dionysusdesign.com/produc...bd7eb202a943b1

I guess the price of a micro servo is reasonable.

Nice thing about it is it allows two servos (nose and mains) to be slowed down and has a fail safe should the Rx not feed the signal properly. Of course, I assume this means power to the servos must still be intact.

David.

the 9303 does it straight off the bat.

Not that it's much help, unless you're looking to upgrade

EMS/Jomar has an item that does this as well. I think theirs has some kind of provision for sequencing gear doors, too. Their website:
http://www.emsjomar.com/
Sonic Tronics also has two units that do this:
http://www.sonictronics.com/xcart/home.php?cat=357
Happy shopping!
Kevin

Only proportional servos, the type normally used for flight control functions can be slowed down with any of these devices. Retract only non-proportional servos, those that only have two positions (gear up or down!) can not be slowed down in any manner.
You will probably hear that applying less voltage will result in some slowing down, which is true, but it will also result in reduced power.

So would you say that these devices are essentially a potentiometer - variable rate resistor - that allows one to reduce the voltage to the servo? I would think that what would be desireable is a capacitive device that discharges at a specified rate - i.e., reduced rate current @ constant voltage.

My gear is very light so torque is not so much an issue but it is important the servo receive full voltage so that the end points allow the servo to lock the gear up/down.

David.

David.

There is a simple way to slow the servo( if the servo is of the older large retract type). Open the servo, push/unscrew, the motor out and "if the space will allow", install a lesser tooth gear on the motor shaft, then re-set the gear mesh. This will simply change the gear speed of the servo. The nice by product is a more powerful servo.
Your servo may be to small for this mod. I've been using a large retract servo with this mod in my Platt FW190 A4. This will give a retract time of 3~4 seconds. Hope this will help.

REGARDS. DAVE.

Nice one Dave!

I'll keep that one in mind for larger models unless you think it's doable with a micro servo (Hitec HS-65MG)?

David.

No, not at all. What they do is modify the incoming pulse. The pot is there to change the rate of change that is allowed for the pulse.

The incoming pulse will be near one of the two extremes (1-2ms), and when you flip the switch it goes to the other extreme. The circuitry in the middle (easily accomplished with a micro) reads the incoming signal, reads the pot position, and then adds or subtracts an amount based on the pot value to the incoming pulse, and then sends that to the retract servo.

You still have full torque.

My MC35's are in. I hope to get some comparisons between the HS-55 and them tonight, hopefully as a video.

Andy

Andy,

thanks. That's exactly what I was hoping for. So, evidently there is other circuitry (e.g., a capacitor) beside the potentiometer which affects the rate of change to the signal being fed to the servo. I guess there is some analogy with the way dual rate proportional channels function - instead of the rate of change being applied to displacement, it is applied to transit time.

I was finding it difficult to understand why slowing the servo down would reduce its torque.

Good stuff about the MC35's. I'm sure they'll blow the HS-55's away.

David.

The circuitry is most likely a micro, since it can accomplish all that is necessary far cheaper, but it is possible to do it with analog circuitry (a 555 plus some caps and resistors).

If you are driving analog servos, the frame rate can be boosted and actually increase the torque.

Andy