Radio Remote Control for the

Minolta DiMAGE A2


Last Updated 21 Mar 07
Copyright 2004 by Stephen Vermeulen


More general information on the Minolta A2.

This thread shows a home made remote shutter and focus switch unit. Another person has made an IR remote. After reading about these I have made a similar device based on the receiver I extracted from a small radio controller car.

A rather nice commercial radio remote (the ZS-2) is made by Zap-Shot (reviewed here), but it does not appear to be compatibile with the A2 (though it might be with a cable adapter plug...). Still, its about $100 more than my ugly hack.

The key thing to look for is a remote controlled toy that can execute two control channels at the same time, which is probably pretty common since most of these will allow you to steer at the same time as you are accelerating or breaking. The reason for the two control chanels is then you can send a command on one to initiate the focus lock; and while locking the focus, you can send a command on the other to activate the shutter.


Here is a picture of the car I sacrificed (it cost me CDN$9.99, on sale for 1/2 price at our local LondonDrugs). As is typical of many such "made in China" items there is no clear identification of the manufacturer, but the UPC is 36386-47298 and its "ITEM# GM7298", other text on the package includes "Stunt Vehicle", "Turbo Twister", "Super Speed", "Micro Scale R/C".

Stunt Vehicle

Here is the top of the box it came in:

Box top

Here is the side:

Box side

Bottom of the box:

Box bottom

And the side with the UPC bar code:

UPC bar code

The first thing one does is to unscrew the top, revealing a small radio receiver circuit board and a pair of small NiCad (or maybe NiMH) batteries (the big green object) below:

Insides

and another view:

More guts

Then one unscrews more things and prys the board off the chasis (here it is still attached to the two motors, one of which is still inside the rear axle assembly), the large black wire is the antenna:

The disassembled car

A closeup of the controller board (the underside):

The controller board

Now one cuts off the motors (the red and blue wires) and solders this all up to an opto-isolator chip (an ISOCOM ILQ2 which I found at my local Active Components, I was really wanting the dual version, but they only had the quad version in stock).

The circuit is pretty simple, just connect the red and blue wires in pairs to pins 1 and 2 (for the first motor) and pins 3 and 4 (for the second motor), it does not matter which way around you do this as the voltage reverses depending on which controler button you press.  You then connect the output pins (13, 14, 15, 16) the following way (pins 14 and 15 are connected together):

ILQ2 Chip Pin
Connected Item
1
Red wire that went to motor 1
2
Blue wire that went to motor 1
3
Blue wire that went to motor 2
4
Red wire that went to motor 2
13
Pin 1 of the camera connector
14
Pin 2 of the camera connector
15
Pin 2 of the camera connector
16
Pin 3 of the camera connector

Here is the underside of the project circuit board:

solder side

and the top side of the circuit board (the white dot on the ILQ2 chip is pin 1, its by the letter F on the circuit board). You don't need to provide any power for the chip as it gets this from the red and blue cables that would have driven the motors:

Top side

I put this in a case from a DDS3 tape cartridge:

Finished unit

The black wire is the antenna, the small plug with the red and white wires is the recharging cord that you attach to the transmitter unit to recharge this before use, and the long grey cable is the camera connection - this was made from a PC sound card cable.

PC sound cards come in two flavours, one has a large connector and one has a small connector. The large connector is too large for the camera (the spacing between the pin holes is too large) though it looks like it might fit. The small connector will fit once you remove one of the outer connectors to make it a 3 pin cable. The following picture shows the two types of connectors you will find, you want the small type (this is after I shaved off the 4th hole by using a razor knife):

small and large connectors

And yes, it really works! Note: if you put the connector into the camera upside down nothing bad is going to happen, all that happens is that the two buttons you use to control the shutter and focus will be swapped.

To use this you must press and hold down the focus lock before and while pressing the shutter button - the camera will not take a picture if you just press the shutter button on its own.

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