BASICS / CAMERA CRADLE / 360° SERVO CONVERSIONS

Method 5 - Pan/Shutter Release on One Channel

Figure 13 This method is taken from Scott Kroger's web pages. I've rewritten some of the instructions and added illustrations to help those that may not be well schooled in electronics.

The Pan Servo Modification
Open the servo and perform the modifications as described in method 4. Next choose one of the two following modifications that make the servo turn in only one direction (the second method is easier):

1. Unsolder one of the two servo motor connections and solder a diode between the motor and the board. Do not worry about the polarity of the diode yet.

                       -OR-

2. Scratch a "break" in ONE of the two traces on the servo circuit board labeled in RED. "Break" the left trace for clockwise rotation or "break" the right trace for counterclockwise rotation. Of course the rotation can be switched by the reversing switches on the transmitter.

Then quoting directly from Scott's page, "Adjust the transmitter trim control for the Pan/Shutter stick to dead center and set the stick to the position desired to initiate panning (I use 1/2 of full left travel). Turn on the transmitter and receiver. Adjust the servo "pot" until the motor just stops. Center the Pan/Shutter stick. If the motor starts spinning again flip the transmitter channel reversing switch or reverse the diode [Ed- if you used method #1 above]. Mark the position of the pot shaft. The servo adjustment is now complete."

Advantages-
Eliminates the need for one channel. Three axis movement and shutter can be accomplished using a 3 channel R/C system.
The rig can be hung directly from the servo output.
External gears are not required.
(some KAPers go ahead and gear the final output down 4:1 to make the panning action slower.)
With no external gears the panning action will be at the servo's normal operating speed.
With no external gears the servo requires minimal space on the KAP rig.


Disadvantages-
Servo must be open and modified.
Can not use most mini-servos because of partial gears.
If you turn past you aiming direction you have to go all the way back around.

 

THE SHUTTER SERVO/SWITCH MODIFICATION

Figure 14 Figure 15 Figure 16 Figure 17 If you are not familiar with how an electronic shutter release works go to Cris Benton's "KAP Rig No. 2" page.

Mechanical shutter release
Use a unmodified servo and attach it parallel to the same channel as the pan servo you modified above. Position the unmodified servo above the camera shutter button in a manner that will cause this servo to engage the shutter button when the transmitter lever is moved in the direction opposite the pan servo activation.

You can purchase "Y" connectors that allow you to plug two servos to the same channel, or you can splice black, red, and yellow wires to each other and to a connector (Fig. 14).

For electronic shutter release
(This technique creates an R/C operated switched, and could be used with systems that have a dedicated shutter channel)

1. Remove the motor from the circuit board.

2. Cut two 2 inch lengths of insulated connecting wire. 24 gauge is a good size.

3. Solder one wire to each of the coil posts on the relay (Radio Shack 275-232).

4. Drill holes in the side of the servo case using the drill plan (Fig. 15). The group of three posts should be toward the bottom of the servo case. Make sure the holes will be above the circuit board when it is placed back into the case. The holes should be big enough to allow your connecting wire to pass through. The top single hole will have to be drilled in the top servo case. remove all the gears and gear pins.

5. Push the two loose ends of the wires soldered to the coil posts through their respective holes from the outside.

6. Solder each end to the circuit board where the servo motor was originally attached.

7. Drill one hole through the narrow end of the middle servo case on the end where the servo motor was located. Make the hole big enough for the 3 wire cable and sub mini plug that connects to your camera.

8. Solder the 3 wires of your electronic shutter release cable according to Fig. 16

9.

-If you preferred method 1 above for your pan servo, then solder a diode to the same terminal as in the pan servo conversion, but with the diode reversed, and solder the coil legs of the DC relay between the other motor terminal and the free end of the diode.

-If you preferred method 2 with the pan servo, "break" the other trace and solder the coil legs of the DC relay directly to the two terminals where the servo motor was connected.

10. To adjust the servo modified for electronic shutter release Scott says, "Set the Pan/Shutter stick to the position desired to actuate the shutter (I use 1/2 of full right travel). Turn on the transmitter and receiver. Adjust the position pot until the relay contacts click. Center the Pan/Shutter stick. If the relay contacts remain closed, reverse the diode [Ed- if you used method 1]. The shutter servo adjustment is now complete."

11. Push the relay posts with their soldered wires back into the servo case and reassemble the servo, leaving out the motor and gears that you removed earlier.(FIG 17)



You may be able to find a relay small enough to fit inside the servo case from another source, make sure that you understand relay terminology if you decide to look for a different relay. Radio Shack had a small relay that would have fit nicely except it was a normally closed style which would not work. Another option is to mount the modified circuitry into another case

 

RELAY TERMINOLOGY GUIDE

SPST - Single Pole Single Throw.
This is the type you need along with N.O. The one input line is either connected or disconnected to the one output line.
SPDT - Single Pole Double Throw.
The one input line is connected to one or the other of two output lines.
DPDT - Double Pole Double Throw.
Two input lines are connected to one or the other of two output lines.
N.O. - Normally Open.
This is the type you need along with SPST. This means that there is no connection between the input and the output until a current is applied to the relay coil.
N.C. - Normally Closed.
You do not want this type. This means that the input and output are connected until a current is applied to the relay coil, then the connection is broken.