Wireless Remote

Wireless remote release by Dr. Leon J. Arp

RADIO CONTROL REMOTE

FOR

MINOLTA DIMAGE 7 CAMERA

 

GENERAL BACKGROUND INFORMATION

BY

Dr. Leon J. Arp

January 2002

 

 

Introduction

 

This radio controlled (RC) wireless remote for the Minolta Dimage 7 digital camera uses a radio control transmitter and receiver from an inexpensive radio controlled toy truck that was purchased from a BIG LOTS store for less than $20.00.  The additional circuitry required to lock the focus and/or exposure in the D7 camera is shown in the accompanying schematic drawing.  Since I do not have schematic drawing software, the schematic was hand-drawn with a lead-pencil. Therefore, it is not a great work of art, but it is readable and it works.

 

New Circuitry per Schematic Drawing

 

I recommend you construct the new camera controlling circuitry that will be connected to the RC receiver on perf board that has copper foil laminated to one side of the board. This material is available from Radio Shack. Make every effort to keep all of the components closely spaced so as to keep the controller's circuit board as small as practical. This will help keep the receiver and camera controller small and convenient to use.

 

The RC Transmitter

 

The RC transmitter and receiver, I chose, operates on a frequency of 49 MHz. The transmitter has an on-off switch, a power on indicating LED, a whip antenna, and two small Joy Sticks (for controlling the truck forward and reverse and left and right). I removed the whip style antenna and replaced it with a piece of stranded wire of a length equal to the whip antenna. I made no other modifications to the transmitter.

 

The RC Receiver

 

I carefully disassembled the truck and removed the RC receiver and its two drive motors. One drive motor was connected to a driver gearbox and used for actually driving the truck forward-and-backward and the other drive motor was connected through another small gearbox to steer the truck left-and-right. Just to be on the safe side, I used my D7 to photograph each of the disassembly steps so I would have a record of what was connected to what. I found that the wires, used to connect the receiver to the power on-off switch, the batteries, the whip antenna, and to the motors, are quite small and prone to break loose from their termination points.  When and if this should happen to you, it will be very comforting to have color photographs of both sides

 

GENERAL BACKGROUND INFORMATION

Continued

 

 

of the etched circuit board and the wires connecting the etched circuit board to the various components so you will know exactly what wire to reattach where!

 

Receiver Operation

 

The receiver outputs of interest to us are the two output lines that are connected to each of the two direct current motors in the truck. The two output lines connected to each of the two motors normally have NO POWER present on either wire while the truck is not being driven forward-or-backward or being steered left-or-right. As soon as the transmitter tells the receiver to start one of the two motors, one of the two wires connected to that motor will have + voltage polarity supplied to it by the receiver circuitry and the other wire will have - voltage polarity supplied to it.  When the transmitter tells the receiver to reverse the direction of rotation for the motor, the voltage polarity supplied by the receiver to the two wires connected to the motor will be reversed. Finally, if the transmitter tells the receiver to stop driving a motor, the two wires connecting the motor to the receiver will again have NOW POWER applied and obviously the motor will stop running.

 

See Circuit Schematic Drawing

 

The remaining text will refer to the accompanying circuit schematic drawing. Once you have successfully removed the RC receiver and drive motors from the truck body, disconnect all of the associated component parts, the power on-off switch, the battery box or connector, the two motors, and the receiver's whip antenna. Caution: keep track of, with photographs and/or notes, which wires are connected to what and where!

 

NOTES:

 

  • 1. All circuit and component termination points that are connected to the ground symbol are to be connected to the negative (-) terminal of the receiver's battery. All circuit and component termination points that are labeled +6V are to be connected through the power on-off switch to the positive (+) terminal of the receiver's battery.  The two wires you remove from one of the drive motors will be connected to the two input lines marked [INPUTS (A. and B)]. In addition, the two wires you remove from the second drive motor will be connected to the two input lines marked [INPUTS (C. and D)].
  • 2. This circuit allows you to lock the focus and/or the exposure in the D7 by keying the transmitter in one direction and then to release the shutter by keying the transmitter in the opposite direction. For instance, if you push the transmitter key away from you the focus and/or exposure can be locked. When you release the transmitter key, nothing new will happen.  When you pull the transmitter key toward you the shutter can be released.  After you release the shutter to take the image, you will want to unlock the focus and/or exposure.  This can be done by moving the second transmitter key to the left. If you move the second transmitter key to the right the relay labeled "FOR WHATEVER" will close and remain closed for as long as you keep the transmitter keyed. You can use the output of this relay FOR WHATEVER function pleases you. Finally, you will have to decide which transmitter key will do what for any direction you choose for moving the key.

Illustrations:

Pictures of the completed remote

 

Schematic diagram

RADIO CONTROL REMOTE

FOR

MINOLTA DIMAGE 7 CAMERA

 

PARTS LIST:

 

       Quant.     Description

 

          • 2 100 ohm - watt resistors
  • 4    220 ohm - watt resistors
          • 3 10 K-ohm - watt resistors
          • 1 10 microfarad - 10 volt electrolytic capacitor
          • 6 Germanium switching diodes
          • 4 1N-914 Silicon switching diodes (Radio Shack - 276-1620)
  • 3    Silicon NPN switching transistors (Radio Shack - 276-1617)
          • 2 Green light emitting diodes
  • 2    Red light emitting diodes
  • 4    SP-ST - 5 volt relay (Radio Shack - 275-240A)
  • 1    Power On-Off switch of your choice
  • 2    Input plugs and sockets of your choice
          • 2 Output plugs and sockets of your choice
          • 1 Project Box 6x3x2 inch (Radio Shack - 270-1805)
  • ?    Connecting cables of your choice