How to turn on small 3.5v motor using a Pyro electric sensor

I need to use a PIR sensor to activate a 3.v motor, how would i go about doing that?

The motor needs to turn off when the sensor is not activated.

I am very bad at electrical circuits and have no idea what goes where, if some can explain the components i would need and what i would connected where on the arduino and on the breadboard as well as what the code would be.

Really sorry but i am useless at this and really need some assistance


Hi there

Have you chosen your PIR sensor and motor? If so, please post links to them.

These may be useful resources ...

The motor needs to turn off when the sensor is not activated.

If this is all you need, there could be a way to do it without an Arduino. Is there other stuff going on that you need the Arduino for?

All the best


i have not chosen the sensor at the moment as i am confused on which one to get though i am thinking to get this one:

and this is the motor i am going to use: (THE SMALL ONE) it is 3.5v

the arduino was initially supposed to turn on speakers to play something from a mp3 as well but thats really complicated and i will not be able to do that!

That PIR looks very similar to the one in the tutorial I linked to, so should be OK.

If you already have an Arduino, you could build up the PIR side and the motor side of your project using the Arduino (based on those tutorials) to prove that things are working ok.

You could then try removing the Arduino. Your PIR should output a "high" level on its output pin when motion is detected. If you dropped the Arduino and connected the PIR output directly to the resistor in the motor circuit, the "high" will turn the transistor on and start the motor. I think that is the logic you wanted? Motion = motor on, no motion = motor off. You will still need to supply power from the Arduino (as per the tutorials) or substitute another 5V supply, and keep the arrangement of motor, transistor, diode and resistor the same.

One point to note, though. The motor tutorial uses an analog PWM output from the Arduino to give variable speed motor control. The output from the PIR will only be a steady high or low. When it is high, the transistor will be switched on (not alternating on and off quickly as with PWM). So the motor will only run at one speed when on, which may or may not be what you need.

All the best


okay that does make sense

could you draw me a diagram of how i would connect it all together if you can please as the two links you sent are confusing me, if you could that would be really helpful!

(not a scientific circuit) i would not understand

and yes the motor spinning at the same speed is fine

Are you OK reading and understanding the breadboard layouts they show in those tutorials?

If so, I can show how they would connect together. Won't be able to do it until the weekend, though.



Hi, sorry its been a long time, but the ciruit did not work

I have a block diagram of a possible circuit, could you draw me a diagram like last time how i would be able to connect it please

the images show a older version of the circuit, the only changes i have made is that that the sensor has been replaced by a passive pyroelectric one, and the relay is connected to two outputs, a mp3 connected by a PCB mounted stereo jack, which is connected to another one PCB mounted stereo jack, that is connected to speakers.


Monish, the images are too big to view easily. Can you repost them at smaller size.

the images show a older version of the circuit

So, can you draw a diagram of the current version.

And what help do you need? Are you trying to build a circuit that does not need the Arduino?



Before you complain about nobody answering your post let me tell you why that might be. 1) You are shouting in the thread's title - that is considered rude.

2) You did not read the how to use the forum stick post that told you about sizing pictures correctly. Click on one of those pictures you posted and see how stupidly large they are so you can't see anything. Not taking note of that sticky is considered rude.

3) The chances of you successfully learning something from a text reply seem slim. The project is way too complex for your current skill level. Try and do some more low level tutorials first and gain some basic skills.

So the idea is that when the sensor is activated through motion, a motor will start to spin and speakers will play music.

The Diagram is a older version and i have now replaced the photodiode/led emitter with a pir pyroelectric sensor.

I have a basic block diagram of all the components needed to make the circuit work, i just don’t know how to put it all together (wiring all the connections on a breadboard)

There are two PCB mounted stereo jacks. One connects to the mp3 through a double male 3.5mm jack, the other connects to a speaker. The two PCBs are connected by soldering on the top I presume?

Can someone show me how to connect everything? PS. I am new to arduinos and not very good electrical circuits (Cant understand them) can someone show me a diagram to show how i connect what where?


B3 - How it Works Circuit - Copy.jpg

The current version is the same, the only change is the sensor used, so the led emitther/photodiode replaced by the PIR sensor

Yes sorry, iv sent them again

B3 - How it Works Circuit - Copy.jpg

I was hoping to have the arduino as the power source and to adjust the delay times of the music and motor.

I just need help with wiring the components together, (what goes where)

Im pretty sure i need a resistor in there somewhere as well, maybe 100k