Servo questions

[Madman]

A servo that I was experimenting with has three wires leading to it. A simple DC connection to any two of the wires does nothing. However, if I open up the servo case and by-pass the tiny circuit board, connecting the DC power directly to the motor leads, the servo works like I would want it to work. Anyone have any problems with this set-up :impatient:

 

[MRail]

There's a possibility of driving the servo against or past its stop position, and causing damage.
Apart from that, can't see any other problem, but I'm no RC expert.

 

[Madman]

So if I manage to figure out which two wires are the power wires, how would the servo operate without the signal wire, or would it? What type of signal is the servo looking for?

 

[Doug]

http://en.wikipedia.org/wiki/Servo_control

 

[nicebutdim]

To be honest you won't really get a servo to operate without some kind of driver. The red and black wires are a permanent 5v supply to the servo while the orange (or white) is the signal. The servo operates by a constant set of pulses on the signal wire. Depending on the frequency of the pulses determines the position of the servo. I've tried making a 555 circuit to operate a servo before and failed miserably. Without really good electronic knowledge or a Picaxe circuit, they're operation is quite difficult to control. There are servo tester boards which are available quite cheaply that enable you to control servos manually.

 

[gregh]

Here's a simple and cheap servo tester. Turn the knob and the servo rotates. Needs a 6V supply (5V is erratic) on the red/black wires and plug servo into either of the pair of 3 connectors.
http://www.hobbyking.com/hobbyking/store/__17143__Simple_Servo_Tester.html < Link To http://www.hobbyking.com/...mple_Servo_Tester.html


plug an esc motor controller instead of servo and control motor speed!

 

[ge_rik]

Here's a simple and cheap servo tester. Turn the knob and the servo rotates. Needs a 6V supply (5V is erratic) on the red/black wires and plug servo into either of the pair of 3 connectors.
http://www.hobbyking.com/hobbyking/store/__17143__Simple_Servo_Tester.html < Link To http://www.hobbyking.com/...mple_Servo_Tester.html
plug an esc motor controller instead of servo and control motor speed!

I bought something similar from HK (2.20UKP inc postage - how do they do it?)

http://www.ebay.co.uk/itm/4-8V-6V-C...sGames_RadioControlled_JN&hash=item43b3bc0bb8 < Link To http://www.ebay.co.uk/itm...mp;hash=item43b3bc0bb8

I've been considering using servos to control my semaphore signals but am concerned about weatherproofing them. Any ideas anyone?

Rik

 

[nicebutdim]

Here's a simple and cheap servo tester. Turn the knob and the servo rotates. Needs a 6V supply (5V is erratic) on the red/black wires and plug servo into either of the pair of 3 connectors.
http://www.hobbyking.com/hobbyking/store/__17143__Simple_Servo_Tester.html < Link To http://www.hobbyking.com/...mple_Servo_Tester.html
plug an esc motor controller instead of servo and control motor speed!

I bought something similar from HK (2.20UKP inc postage - how do they do it?)

http://www.ebay.co.uk/itm/4-8V-6V-C...sGames_RadioControlled_JN&hash=item43b3bc0bb8 < Link To http://www.ebay.co.uk/itm...mp;hash=item43b3bc0bb8

I've been considering using servos to control my semaphore signals but am concerned about weatherproofing them. Any ideas anyone?

Rik

I used ideas from here http://www.google.co.uk/url?sa=t&rc...-4CYBQ&usg=AFQjCNFaxRyLZetDs2yIjM7K25o_uhWpnA < Link To http://www.google.co.uk/u...ZetDs2yIjM7K25o_uhWpnA

 

[Madman]

Thanks everyone. Slowly, painfully I might add, I am gaining some minimal knowledge of these things.

 

[MRail]

[style="color: #3366ff;"]I've been considering using servos to control my semaphore signals but am concerned about weatherproofing them. Any ideas anyone?
[style="color: #339966;"]I used ideas from here http://www.google.co.uk/url?sa=t&rc...-4CYBQ&usg=AFQjCNFaxRyLZetDs2yIjM7K25o_uhWpnA < Link To http://www.google.co.uk/u...ZetDs2yIjM7K25o_uhWpnA

Interesting ideas on waterproofing.
A year or so ago I had a bad experience.
At a 16mm garden meeting, we had a fairly heavy shower, and kept bravely going.
Some guys' open wagons were full of water, and my Billy suddenly took off uncontrollably.
Back home, investigatons found water in a Futaba servo.
It did recover after an overnight drying session.
A lesson was learnt!

 

[ge_rik]

I've been considering using servos to control my semaphore signals but am concerned about weatherproofing them. Any ideas anyone?

I used ideas from here http://www.google.co.uk/url?sa=t&rc...-4CYBQ&usg=AFQjCNFaxRyLZetDs2yIjM7K25o_uhWpnA < Link To http://www.google.co.uk/u...ZetDs2yIjM7K25o_uhWpnA

Very useful - the video at the end of the page makes it look relatively easy. Not entirely convinced by the o-ring seal but the rest looks really useful.

Anyone know anything about the 'mineral oil' be recommends?

Rik

 

[nicebutdim]

I would have thought this http://www.ebay.co.uk/itm/Clear-Whi...5?pt=UK_Health_Massage_RL&hash=item2306e2db31 < Link To http://www.ebay.co.uk/itm...mp;hash=item2306e2db31 as it must be safe on all plastics, nylon etc.

 

[ge_rik]

It is possible to use a plastic electronic components box (about £1.50) sealed with the screws and silicon (easy to get off if required). A hole in either end can be fitted with a rubber conical concertina type boot of suitable model size (model car web pages) so that the actuating rod and supply wire entry/exit can be kept sealed as well with a safe type grease, The box can be filled with the grease of a safe type (or silicon adhesive (bath type or similar)).

Just a suggestion

Thanks Ross - that sounds do-able and less messy than the mineral oil approach

Rik

 

[ge_rik]

I would have thought this http://www.ebay.co.uk/itm/Clear-Whi...5?pt=UK_Health_Massage_RL&hash=item2306e2db31 < Link To http://www.ebay.co.uk/itm...mp;hash=item2306e2db31 as it must be safe on all plastics, nylon etc.

Is that the same as baby oil? Now, I've heard that has a multitude of uses ..........

Rik

 

[nicebutdim]

I would have thought this http://www.ebay.co.uk/itm/Clear-Whi...5?pt=UK_Health_Massage_RL&hash=item2306e2db31 < Link To http://www.ebay.co.uk/itm...mp;hash=item2306e2db31 as it must be safe on all plastics, nylon etc.

Is that the same as baby oil? Now, I've heard that has a multitude of uses ..........

Rik

How about KY....