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Topic: Help with the circuit (Read 416 times) previous topic - next topic


Feb 17, 2018, 11:03 am Last Edit: Feb 18, 2018, 12:41 pm by hardik311095
I have attached below the circuit to the project that I am developing.

Is their a problem with the connections I have made?

Do I need to connect something to ground? Any other problems that you would like to point out?

Specifications of components:

1. Vibration motor:

Type: 0834
Material: iron
Size: 8 x 3.4mm Approx, wire 15mm(L)
Rated voltage : 3.0V DC
Rated current: 70mA Max
Rated rotor speed: 12000±2500RPM Min
Operating environment: -20℃~+60℃
Save environment::-30℃~+70℃

2. Battery: 3.7v

3. Transistor: 2N2222

4. Capacitor: 0.01uF

5. Resistor: 330 ohms

6. Diode: 1N4001


void setup()
pinMode (3, OUTPUT);
pinMode (13, OUTPUT);

void loop()
digitalWrite(3, HIGH);
digitalWrite (13, HIGH);

// planning to use 4 more motors so simply will add a few more lines.

Link to the Arduino Pro Mini: Arduino Pro Mini

Please please  :( I would really appreciate your help, I am stuck so bad, please help me in my first project.


Feb 17, 2018, 11:19 am Last Edit: Feb 17, 2018, 11:40 am by 6v6gt
If you are just starting, you should draw out the circuit using conventional circuit symbols on paper and include a picture of it here. The Fritz diagrams have rightly a bad reputation because important detail is blurred and obscured. E.g. it is impossible to see the pin markings on the Uno board.

To me, it looks like there is a number of problems:
1. The diode is in an odd place. it should be reversed across the motor and the capacitor (if needed) in parallel with it.
2. The pinout for the 2N2222 appears reversed from what I can see.

You should also include the code you are going to use.
OP's picture:


Feb 17, 2018, 12:08 pm Last Edit: Feb 17, 2018, 12:47 pm by hardik311095
I have uploaded the conventional circuit diagram as well now. Thank you.

The code is simply to run them all at the same time. Maybe, varying their intensities if I want to. Otherwise just switching ON and OFF.


To me, that looks fine. I'd consider the capacitor across the diode as optional:

OP's additional picture:


Varying their intensities if I want to.
Pin 13 is not PWM.


I've just noticed this:

Include a link to the pro Mini you are going to use. Hopefully it is clear what regulator it uses. Your battery is 3.7 volt and there may be an issue there. It may be you have to put a diode in series with the battery to drop the voltage and then connect it to the 3.3V terminal of the Arduino instead.


So, can I go ahead and connect 4 more in a similar fashion (a total of 6 motors)?

The total current that can be sourced from Arduino I/O pins is 200mA will connecting 6 motors cause a problem of any kind or am I good to go?

Is the battery I have chosen good enough?

thank you so much.

PS: I have included the link to the pro mini I am using.


I don't know how much current the 3.3V regulator on a Pro Mini can supply but you should take that into consideration. 

It would have been nice to have the board on the drawing labeled as Pro Mini so that we know. 


Don't power the motors through the tiny (<150mA) regulator of the ProMini.
Connect motor(+) directly to batt(+).
Same for the emitters of the 2N2222 transistors.
Connect them directly to batt(-), not via ProMini ground pins.

For full saturation of the 2N2222 transistors (max motor power), base current should be 10% of collector current.
Lower the 1k resistors to 330ohm.
10n across the motors is more than enough.
Try to avoid pin13. That pin could change state during bootup.


The conventional diagram is not only better readable, it's clearly correct. The Fritzy is clearly incorrect, even though many components are ambiguous to what they even are (such as those blue things - I guess that are the capacitors?).

The Arduino's regulator is best not used to power motors (not even a single one). The stall current of a single motor is probably too much.

Better connect them directly to the battery - you will have about 0.6V drop over the transistor anyway! So a full battery (4.2-4.3V) provides a bit higher voltage but that doesn't matter for most motors and you anyway have the PWM control.

For the Pro Mini: would it be safe to power it at a bit higher voltage on the Vcc pin? The processor won't have a problem with it, it's rated to handle up to 5.5V. Don't know about other on-board components.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.


Feb 17, 2018, 12:56 pm Last Edit: Feb 17, 2018, 01:01 pm by hardik311095
10n across the motors is more than enough.
Can you please explain the quoted statement, LEO.

Also you suggest on directly powering the motors through the battery. Well, in that case can the battery that I have purchased handle 6 vibrational motors together? I can't use multiple batteries because I want to keep the project small.

thanks for the support


Well, in that case can the battery that I have purchased handle 6 vibrational motors together?
If the battery can't handle it on its own, you have no chance whatsoever to do it through the Arduino's regulator in the first place.

Check your battery's current supply ratings.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.


which is the smallest possible battery that will be able to power the arduino pro mini as well as the 6 vibration motors?


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