How to use DC Motor without extra batteries/Voltage

How do I use the DC Motor without batteries, When I push a button I the motor to turn on, I think I need a transistor. Also, I would like to add some leds.

Kevparang:
How do I use the DC Motor without batteries, When I push a button I the motor to turn on, I think I need a transistor. Also, I would like to add some leds.

magic is a good source of power.

If you are thinking you can have the Arduino power a motor, you are deluding yourself. The standard Arduino can only source 200mA of 5v and 50mA of 3.3v. Usually a motor needs more power than the Arduino can provide.

The Arduino can control a motor that is powered from an external source.

Do a search on lowside drivers

chuck.

Read this
http://www.thebox.myzen.co.uk/Workshop/Motors_1.html

With an n-Channel MOSFET (Metal Oxide, Field Effect Transsistor)

Yes, correct, that's what you need.

The Arduino can't handle the amount of current a DC Motor requires.

You'll also need a diode, which my drawing doesn't show.

An IRLB3034PBF from Mouser Electronics will work perfectly with what you want to do.

Here's the wiring diagram.


The Lightbulb, in reality is a AC load. But it's used in my drawing as the load. Replace the Lightbulb with a motor, and use a 15kΩ Resistor as a pulldown resistor.

Using a 15kΩ Resistor between the Gate & Source, will only draw 0.001+ mA of current.

I also use this exact MOSFET in Box Mods, to protect a momentary switch. The Coils in my box mods draw roughly anywhere from 20A to 30A.

n-Channel Mosfets are excellent electronic components for doing stuff like this.

However, you will need an external power source, roughly 3.5 - 5v should be safe to saturate the gate, and turn on the mosfet.

The Lightbulb, in reality is a AC load.

No it is a DC load.

Using a 15kΩ Resistor between the Gate & Source, will only draw 0.001+ mA of current.

Very very bad advice. The current draw on the gate of a FET is negligible when it is on, it is only when you switch it you get a current surge due to charging up the capacitor which is what the output pin sees as load. If using PWM ( which we aren't here ) you need something like a 150R resistor to keep the surge down to the 40mA absolute maximum from a pin. If you use 15K the the turn on will take a lot longer and the FET will get hotter as a result.

Kevparang:
How do I use the DC Motor without batteries,

Your title says "without extra batteries" - which do you mean?

You can power an Arduino and a motor from the same battery if they are connected to it in parallel. But you should NOT power the motor THROUGH the Arduino.

...R

I did a video for the OP. To show the current draw on the MOSFET I've mentioned. I'll also do another video latter to show that 15kΩ Resistor is fine for turning on and off the load. That will be latter. I'll use a Solid State relay, with the MOSFET I've listed, and switch on and off my CFL lights with the MOSFET connected on the DC side of the SSR. Normally, this SSR I own draws roughly 4.48mA. But with the MOSFET, it should only draw 0.33mA, like I've demonstrated in the video. The 2nd video will also prove further that it doesn't matter if there's a 14 Watt load, or a smaller load, the current draw at the gate on the n-Channel MOSFET, is constant as far as I can see, which so far, is 14 Watts, 1.160 Amps.

The Mosfet is capable of much more than a measly 1.160 Amps, as I've mentioned, I use this exact Mosfet for coils that heat up, and draws like 20 to 30 amps. I've also have never felt the mosfet heat up wile doing stuff like this. But the coils that heat up usually only last a second or two so..

A MOSFET does indeed heat up, because that's why a MOSFET has a metallic backing on it, to be hooked up to a heatsink.

So here's the video I did. Hope the OP likes it, and finds it useful.

Kevparang:
How do I use the DC Motor without batteries, When I push a button I the motor to turn on, I think I need a transistor. Also, I would like to add some leds.

How do I use the DC motor without batteries, when I push a button, the motor turns on.

If your not going to use batteries, I'm going to guess and say you're either going to be using an Arduino, a microcontroller, or a dedicated power supply like a wall-wart power supply.

Yes, you need something like an n-Channel MOSFET, which is called a Metal Oxide Field Effect Transistor.

You can also add as many LED's as you like. Depending on what type of LEDs your using, you'll either need to calculate the resistor value for the LEDs, or you'll need a special driver for the LED's.

If they're regular through hole LEDs, I'd recommend hooking them up in parallel, and using a resistor for each LED. To do that, and if they are regular through hole LEDs, you'll need to know the Voltage of your power supply, each Forward voltage, and each forward current of each LED, to calculate the resistor values for each LED you want to hook up in your circuit.

To find the resistor value for the the LED, according to the Datasheet.

First we need to find how much voltage to drop across the resistor.

(Vs) Supply Voltage - (Vf) LED Forward Voltage = (Vd) Voltage to drop across the Resistor.

Knowing that, then we take the (Vd) Known voltage to drop across the resistor, and divide that by the (If) Forward current of the LED.

But people don't usually, to extend the lifespan of the LEDs, they usually use a current a little smaller than the LEDs fully on Forward Current (If).

So.. 12v power supply minus LED forward Voltage 3.3v = 8.7 (Vd) Voltage to drop across the resistor.

Then we take that, and divide that by the LED's known Forward Current (If) to get the resistor value.

So if the LED is rated for 0.020A, or 20mA. Then we use something like 90% of that value.

0.9 x 20mA = 18mA

8.7v / 0.018A = 483.3333 Resistor.

The Resistor can be 483Ω.

483Ω

Alright, so now you also need to know what kind of power the resistor needs to be able to handle. How many watts is it going to dissipate at let's be safe, and say 20mA (0.020A), with a voltage dropped across it of 8.7v

Once again, we turn to Ohm's law.

8.2v * 8.7v = 75.69 / 483Ω = 0.1567 Watts. Or.. 156.7mW, so it looks like a 1/4 Watt LED should be fine, if that was the supply voltage, forward current and forward voltage of your LED, like the blue ones I just got two days ago from Mouser Electronics. But I used a 5v power supply for my circuit, so my resistor value was different. I used a 100Ω resistor. Gave me something like 0.018A.

Anyways, I hope this was helpful.

A MOSFET does indeed heat up, because that's why a MOSFET has a metallic backing on it, to be hooked up to a heatsink.

Yes but with a 15K it heats up more than it should, especially when you PWM it.

I never said it would not work, I said it was bad advice.