So, as I've mentioned before I've been working on a project to connect my Arduino Mega 2560, I believe I know how to do it WITH TRANSISTORS but I have no idea what type I need.
here's a dropbox link to a picture of the robot arm:
here's a dropbox link to a picture of the PCB I aim to connect to:
I aim to connect the 8 pins on the PCB to a breadboard, when current can travel between any of the motor pins and the positive terminal pin the corresponding motor will turn in one direction, they will turn in the opposite direction when current flows between their pin and the negative terminal pin. The LED lights up when the LED pin is connected to the negative terminal pin.
My plan is to use 11 transistors to control the arm. I will connect all of the transistor's bases to the Arduino's pins, 5 of the collectors to the positive terminal pin and the other 6 to the negative terminal pin. Each motor pin will be connected to 2 transistor's emitters (one with the collector connected to the - terminal pin and the other connected to the + terminal pin) the remaining emitter will be connected to the LED pin.
I want it so that when the Arduino outputs 5v at a certain pin, full power is allowed through the connected transistor.
Start over, where do you intend to cut in to the bot, in the control box, in the cable, in to the arm its self.
Does it use servos, motors or a combination?
What are the signals to the "motors" what type of motors?
How do you intend to get feed back to the arduino so that it knows the position of each part of the arm or are you just trying to replace the control box with one you have made? (with buttons for you to control the arm via the arduino).
I intend to connect to the robot by connecting female jump wires to the pins on the PCB I have shown. I think it just uses regular motors, I'm not sure what type but I will try to find out, I intend for the Arduino to somehow auto-align when I first run the program and get the position from that although I am not sure how.
I'm not sure if this is important but it uses 4 1.5v Duracell plus D batteries.
Could somebody please just tell me what type of transistors I want rather than telling me I should use so etching else, I've explained everything in the post, I know The motors need to turn in two different directions and I have explained how my plan accounts for this, so could somebody just give me the answer I have asked for?
colonelhomer815:
I aim to connect the 8 pins on the PCB to a breadboard, when current can travel between any of the motor pins and the positive terminal pin the corresponding motor will turn in one direction, they will turn in the opposite direction when current flows between their pin and the negative terminal pin. The LED lights up when the LED pin is connected to the negative terminal pin.
Are you saying there is a single terminal which makes a given motor turn one way when it is connected to positive and turn the other way when it is connected to ground? If so there must already be some form of driver circuit on the 'motor' side of that circuit. How much current flows through that terminal when you connect it to positive, and to ground?
Yes, yes, the motors turn one way when the corresponding pin is connected to the + terminal pin and the other way when connected to the - terminal, I don't know how it works. I'm not sure about the current, I don't have an ammeter but I'd be willing to get one if it could help me with Arduino in the future.
The next time I read the word H bridges, somebody dies
Could you please read my post fully, I've explained how I aim to do this with transistors, if there is anything wrong with that plan could yup please tell me (BUT ONLY IF YOU HAVE READ THE POST FULLY!)
It looks like the link to the controller is expecting 5 potentiometers, giving analog
signals on those connector pins.
Using low-pass-filtered PWM outputs from the Arduino may be good enough.
Try something like 4k7 resistor from Arduino PWM pin to a 1uF capacitor to ground,
then connect the R-C junction to one of the pins on the connector and Arduino
ground to -ve battery pin on connector.
What voltage is the battery for the robot arm though ? If its not 5V this
method won't give full range control, but analogWrite() ought to at least do something
if its analog voltage control.
Can you open up the controller and check that its a bunch of pots?
The controller doesn't use potentiometers, each motor pin is connected to the centre of a bent strip of metal on the controller, under one side of the strip there is a bit of metal connected to the + terminal pin and the other connected to the - terminal pin. when the lever above the strip of metal is pushed one way, the strip is pushed down connecting it to the bit of metal the leads to the + terminal. When it is pulled the other way, the strip connects to the bit of metal leading to the - terminal pin. I can add a picture of you want.
colonelhomer815:
I'm not sure about the current, I don't have an ammeter but I'd be willing to get one if it could help me with Arduino in the future.
It's an invaluable tool and well worth having if you expect to do any significant work with electrics or electronics, and essential for this particular problem since you need to know the electrical characteristics of the circuit you're connecting in to in order to connect in to it successfully.
If the current required is below about 40mA there's a chance you could drive it directly from an Arduino I/O pin. Otherwise you're going to need a driver circuit. What sort of circuit will depend on the voltage and current you're trying to switch. You absolutely need to know that before you go any further.
I would buy a motor driver and not do the thing with seperate transistors unless totally neccesary.
If you do use transistors, make absolutely certain to turn off one side of the H bidge before turning the other side on.
Also you may want to open up an RC servo, you can connect a DC motor directly in place of the existing motor in a servo and control its H bridge from the SERVO library in arduino.
I just bought a set of jumper wires, a 4 pin connector, an AD-01 breadboard, I've done a little experimenting and I am still not sure how to use them, I will post more information shortly but I can really do with advice on how to use these transistors.
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I would like to set up a transistor so that power is let through (with the collector connected to the green cable on the left, and the emitter connected to the green cable on the righ) when the button is pushed down.
OK look the kit you linked to is just that - a kit. So photo/scan what ever the instructions and let us have a look that way we can see just what you have!.
But from what you have given us so far -( I think - and no one here likes to guess!)
You are cutting in between the switch/control box and the arm - Answer yes or no.
there are just the rocker type switches in the control boxes? Again yes or no.
Each of the motors has 2 wires. (if so it is a motor) 3= servo, 4 = stepper.
If you think that answering these questions is below you, understand that with out good clear information people here will not reply. Note the time between my questions about what you are doing and any kind of clue as to what transistor. This is down to you not providing the required information and not to us.
If they are motors, then from the switches you have described you need a H-bridge per motor and there is no argument!
It's up to to decide if you H-bridge chips, 6 transistors per motor setup as a H-bridge, or motor controller shields/boards.
