robot arm project queries

I've been working on a project to connect my Arduino Mega 2560 to A robot arm I made a few years ago, This is my first real project so I'm a little unsure about a few things. I've asked a question about this before but now I have some images and more information and I still have a few questions about the subject.

Here's a labelled image of the robot arm:

here's an image of the PCB with the pins I aim to connect to labelled:

It's powered by 4 Duracell+ 1.5v D batteries

When connected to the positive terminal pin: The gripper closes M2, M3 and M4 move upwards M5 turns anti-clockwise (from above)

When connected to the negative terminal pin: The gripper opens M2, M3 and M4 move downwards M5 turns clockwise (from above) The LED turns on

My plan is to control it using 11 transistors (2 per motor + 1 for the LED) and connect the gates/bases to the Arduino but there's a few things I'm not sure about: Should this work Would this be the right type of Transistor: ? Would all of the collectors/drains be connected to the battery terminals or would it be different for positive and negative?

I may also have other questions in the future, thank you in advance.


There is when I see the page, do you have the page loaded properly.

I can't see them either....



How odd.

try these links:


I've tried, it didn't work.


Also, from the looks of the USB control interface on the following page, you'll want much heavier MOSFETs that the 2N7000, more like IRL540, etc.

This isn't USB based...

Also I have no idea what a "heavier transistor" is.

It seems to me, you need about 5 signals to control that robot usefully.

Does it use servos or something else ?

That arm contains four motors plus a "searchlight". The nine, TO-style packages on that board you have pictured would be insufficient to form four full bridges.

If you subtract one chip for the searchlight, that would leave eight chips which would more likely be half bridges like the BTS7930.

But to the real question, I doubt these motors consume more than 1A.

It contains 5 motors and an LED, the dropbox links and non-working images show the 8 pins I plan to connect to and a labelled diagram of the arm itself.

hang on, are Mosfets normally on? if so that’s not what I want.

Mosfets are on or off based on the level of the gate. But that's not important now.

If you are thinking of using one mosfet/transistor per motor you will only be able to drive the motor in one direction. That is of course not what you want. You need a full bridge for bidirectional control. An L293 is a common answer for this -- it can drive two motors up to 1A each -- but it's not a particularly durable chip.

my plan accounts for the fact the motors need to turn both ways, if you would follow the dropbox links you would see that.