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JR-Spektrum . Gyro Hobbies . E-flite

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Aerial Photography and Video > How can you make a servo turn slower....
 
 
jonasl
Senior Heliman
Location: From Denmark, but live in Hong Kong

Is it possible to make a standard servo turn slower, I am not thinking about a gear?

Jonas
11-16-2003 Over year old.
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Ace Dude
Elite Veteran
Location: USA

Search the web, there may be some schematics out there.

On some of the high-end radios this can be done from the transmitter. You may want to check to see ifyour TX supports this feature.

Some servos (Multiplex) can be programmed with a speed setting....
11-16-2003 Over year old.
 
 
Dave Barbera
Heliman
Location: Hubbardston, MA U.S.A.

Hi Jonas,

If you don't mind building a little circuit board check this out:

RC-CAM Pan Project

There is a good description of what it will do on that web page. There is also a short video you can download to see what effect the circuit has on a standard servo.

Best Regards,
-Dave
11-16-2003 Over year old.
 
 
Obsessive
Key Veteran
Location: 41.73N 71.41W

Other things to try...

Retract servo
11-16-2003 Over year old.
HOMEPAGE  
 
 
rover
Senior Heliman
Location: Brandon,FL

AFR adustable function rate. It changes how fast or slow the function increases that is your hand moving the stick. If you dont have a radio that has AFR, hitec, has a servo programmer for their digital servos which can adjust this inside the servo only. If you dont want to go that route, you can build, depending on the applications, reduction systems via gears or timing belts to reduce the angular velocity of the output of the servo.

Rover
Mechanical Engineer
11-16-2003 Over year old.
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Ace Dude
Elite Veteran
Location: USA

Too bad the Hitech programmer is about $160. The Multiplex programmer is only about $45.
11-16-2003 Over year old.
 
 
vince
Senior Heliman
Location: Victoria BC Canada

could you not just lower the voltage
11-16-2003 Over year old.
 
 
rover
Senior Heliman
Location: Brandon,FL

you could lower the voltage but, there is a big but, the servo would loose strength, and the electronics wouldbe more prone to take a dump since they are most efficient at running on 5v nominal voltage, lower it to say 3.6? you would loose efficency in the IC and the moment created by the servo would be reduced sigificantly, that is the couple moment AKA torque. In servos the motor speed is controlled by the actual IC within the servo, it recieves info from the RX and tells the servo how fast to go, it is not so much the motor that needs the voltage but the Integrated Circuit. The IC regulates the voltage to control motor RPM

Rover
Mechanical Engineer
11-16-2003 Over year old.
HOMEPAGE  
 
 
mlmcquiggjr
Heliman
Location: Tulsa, OK

Turn servo slower

The quickest solution is to move to the inner hole on the servo arm. Hey, you get more torque too!
11-17-2003 Over year old.
 
 
Harbinger
Veteran
Location: alberta

if your using a stylus

There is a delay you can add to a channel if you have the latest heli card. The radio really has some great features on it and is not as expensive as the other high end radios.
11-17-2003 Over year old.
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Augusto
rrAdvertiser
Location: San Diego, CA

the easiest way to drop the speed of a servo without lowering the voltage that goes into the servo electronics is to put two zener diodes back to back in series in one of the servo motor wires. Just select the zener voltage drop according to how much slower you need the servo to go. Also select the max disipation accordingly. Be aware that the power will also decrease proportionaly. The total applied voltage to the motor will be the battery voltage minus around 0.7 volts pn junction drop for the forward biased diode minus the Zener voltage of the zener biased diode.

Augusto.

Avant Aurora Ultimate
11-17-2003 Over year old.
 
 
WMac
Veteran
Location: Skotlande

I saw a thing called a "servo slow" once, you just plugged it in between the servo and Rx and you could set the speed. You might find it on http://www.ripmax.com

Will


Beep Beep! One Road Travel, with Dominic Byrne!
11-17-2003 Over year old.
 
 
Angelos
Key Veteran
Location: nr Oxford, OX11, UK

jonasl,
can you give us more details about the specific application. Is it for a pan/tilt mount?
11-18-2003 Over year old.
 
 
Augusto
rrAdvertiser
Location: San Diego, CA

You could also have a little cheap microprocessor store the last pulse length and capture the new pulse length and then generate an output pulse that by means of a counter with a delay that slowly matches the captured pulse by adding into a counter in the direction to decrease the difference between the stored and the requested pulse. The speed of the counter can be adjusted to match any speed you want by adjusting the delay used to update the output pulse counter.

There are tons of cheap micros with pulse width capture and pulse width modulation generators that can be used for that.

Augusto.

Avant Aurora Ultimate
11-18-2003 Over year old.
 
 
mr.rc-cam
Heliman
Location: USA

The RC-CAM PanCam can be used for "Servo Slow" applications. It was designed for camera pan and tilt control, but another possible app for this is to slow down retracts.

Another ready to use servo slow: http://www.emsjomar.com/
11-18-2003 Over year old.
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FlightPower
Veteran
Location: Herts UK

Mr RC-Cam

Is this the EMS Jomar item you mean please?

MULTI-MODE ELECTRONIC MIXER
The Digital Aircraft Doohickey (D.A.D.) is a versatile, multi-mode 2 channel mixer. The unit simply plugs between the receiver and servo(s) and offers the following modes of operation:
MODE 1 - Master/Slave (Uni-Directional) Mixing.
Mix any two channels (rudder and aileron, throttle and elevator, etc.) at a selectable rate and optional exponential.
MODE 2 - Full (Bi-Directional) Mixing for V-tails, flapperon, airbrakes etc. with adjustable rates and optional exponential for one or both channels.
MODE 3 - Exponential/Rate Reduction “Soft-center” exponential with selectable servo travel limiting.
MODE 4 - Servo Pacing or Delay Slow down gear retraction, flap deployment, gear door cycling, etc. Programmable from 2 to 30 seconds.
Includes comprehensive instruction manual and receiver connectors. Size 1 x 1.5 x .27, weight .4 ounces. $44.95
11-18-2003 Over year old.
 
 
mr.rc-cam
Heliman
Location: USA

That would work as a servo slow too. But, I was referring to the Gear and Door sequencer. The best link to it is:
http://www.emsjomar.com/main-3.htm

Here is the product description:
GEAR AND DOOR SEQUENCER
A microprocessor driver device which controls and sequences the landing gear mechanism and landing gear doors. Works with air and/or servo controlled systems. Gear servo and door servo travel time individually adjustable from full speed to 10 seconds. Gear doors may remain open ala P-47 or close after lowering gear ala P-51. Gear doesn’t move until doors travel is fully completed. System can control two gear servos with time overlap feature. Individual servo reversing capability on door and gear servos. A “Mayday” feature drops gear at full servo speed for aborted takeoffs, etc. This unit is a must for any retract system. Size 1.5 x 1.5 x .75. Less than 1 ounce. Includes servo connector to receiver. $44.95

11-18-2003 Over year old.
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FlightPower
Veteran
Location: Herts UK

OK thanks - but I'm wondering, doesn't the gear retract device just travel between two fixed points slowly instead of "looking where you tell it to look" slowly?

If that's true, I'm guessing this is a better match:

D.A.D. in MODE 4 - Servo Pacing or Delay Slow down gear retraction, flap deployment, gear door cycling, etc. Programmable from 2 to 30 seconds.

(but I wonder if this is not also a point-to-point travel thing?).

I have all the parts for several PAN-CAM assembles, I even gave in an bought a PIC burner despite the fact that all that kind of thing runs contrary to my brain's internal wiring. Could you have pity on an idiot and tell me exactly how to configure a PAN-CAM so it just slows down servos without losing proportionality please?

J
11-19-2003 Over year old.
 
 
mr.rc-cam
Heliman
Location: USA

It would be best to email EMS for the answer. I have not used the product, so I do not know if it slowly travels to two fixed points or just slows down the travel of the directed servo position. I would expect it to be the latter.

PanCam does not offer proportional positioning. It instead is used as a pan motion control that translates stick postition into pan speed. The operator must decide when to stop the motion. This is the method that was asked for by several folks when it was designed. The demo video on the web page shows examples of its operation.

So, if you need to slow a servo down, but retain proportional positioning, then a "Servo Slow" device is needed. If EMS cannot help, then search for other suppliers of Servo Slows. Or you can use one of the high end Tx's that has that sort of trickery in the mix features.
11-19-2003 Over year old.
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FlightPower
Veteran
Location: Herts UK

That explains a few things (that I probably ought to have known if I'd read the manual). As always - many thanks.

Julian
11-19-2003 Over year old.
 
 
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