## Tuesday, September 20, 2016

### Fleming's Both Hands Rule!

Good afternoon everyone, so I think today is a good day to write about something kind of confusing which is Fleming's Left hand rule and his right hand rule. These rules are just mnemonic or you can call them memory technique to remember the directions of current, magnetic field and motion in both motor and generator.

So first things first remember this;

1. Fleming's Left-hand rule is used for electric motors.
2. Fleming's right-hand rule is used for electric generators.

Now let's talk about how to apply these rules, starting with left-hand or the motor hand.

As we are talking about motor the current and the magnetic field will be given but the force direction will be unknown. If a current carrying wire is subjected to a magnetic field in a perpendicular fashion then the wire will feel a force which is perpendicular to both the direction of current and magnetic field. So we are talking about 3 axis here, if you set say the field and current to x and y axis respectively then the motion will be in z axis. Things are a bit complicated without any visual representation.

Here is a left hand diagram where

Thumb or F is the force vector or the thrust on the conductor or motion of it.
Fore finger or B represents the direction of magnetic field or flux density.
Second finger or I represents the direction of current.

Let's move on to the right hand rule now.

For generators however the motion and the field is given we need to know the direction of current. So thing is if we subject a moving conductor in a magnetic field we will get current which is both perpendicular to the two applied causes. Again let's look at a visual representation.

In here

The thumb is the motion of the conductors.
Fore finger is the magnetic field.
Second finger is the direction of current.

So that's a brief description of Fleming's left and right hand rules.

Left hand.
Right hand.

You can also read my other posts here.

Index to my blog.

## Monday, September 5, 2016

### Raspberry Pi Starter Kit

Good evening everyone. Hope you guys are doing great. So currently single board computers are very popular and getting more more and more popular day by day. Truth to be told there are huge amount of legitimate reasons behind their popularity. If you are however new to all these then this post might help you out. In this specific post I will be focusing on Raspberry Pi and I will go into the reason why in a few moments.

Like I was saying if you are new to this whole single board computer thing I would say start with Raspberry Pi as it has been here for quite a long time so you will get more support. Now let's take a look at what you are going to need to properly work with Raspberry Pi in many different scenarios. So couple things are common for all scenarios, let's start with them.

1. You will obviously need a Raspberry Pi, as for September 2016  I would suggest getting either a Pi 2 or Pi 3.

 Raspberry Pi 3

 Raspberry Pi 2
Let me give you a bit more info on this single board computers. Both of them are ARM based and have a lot of similarities but the newer one has couple more tricks up its sleeve.

System on Chip:

RPi2: BCM2836 Quad Core ARM Cortex-A7 900MHz with VideoCore IV 250MHz
RPi3: BCM2837 Quad Core ARM Cortex-A53 1200MHz with VideoCore IV 300MHz

Audio and Video Output:

HDMI supports 1080p video with audio.
3.5mm TRRS jack for Stereo Audio and Composite Video.

Connectivity:

RPi2:  10/100Mbps Ethernet Port via an USB to Ethernet Adapter on-board.
4 USB 2.0 Port.
1 HDMI, 1 3.5mm TRRS Jack.
40GPIO Pins,
Camera Interface(CSI)
Display Interface(DSI)
RPi3:  10/100Mbps Ethernet Port via an USB to Ethernet Adapter on-board
Bluetooth 4.1Classic, Bluetooth LE, Wi-Fi 2.4GHz 802.11n Standard.
4 USB 2.0 Port.
1 HDMI, 1 3.5mm TRRS Jack.
40GPIO Pins,
Camera Interface(CSI)
Display Interface(DSI)
Power:

5V 2A(Recommended) via Micro USB.

So the major difference here is the Improvement on the CPU side as frequency is bumped from 900MHz to 1200MHz and also the GPU sees a little improvement. The big advantage here is the fact that Raspberry Pi 3 comes with Wi-Fi and Bluetooth. Next thing we need is microSD card to load operating system.

2. MicroSD cards.

As they are inexpensive I would suggest you to buy about 4 of them, 16GB of capacity and Class 10 in speed specification. That way you can keep one or two stable operating system ready in hand to use and maybe one or two more for experimenting.

To power up the device properly a good quality power supply is needed with a good micro USB cable. Personally I use phone chargers and they work just fine. I would suggest getting at-least 2A one but if you plan on using portable Hard drive or something I would recommend getting a 3A one. (Although keep in mind that the combined current output of all four ports are 1.2A)

4. Ethernet cable or Wi-Fi dongle:

Depending on which method you use, you might need an Ethernet cable, a CAT5e would be enough or you can opt for a USB Wi-Fi dongle for RPi2 but for the RPi3 it has built in Wi-Fi. If you are plan on using network attached storage however I would recommend using the Ethernet port as it will provide more consistent speed and better latency.

5. HDMI Cable and 3.5mm splitter:

For connecting with TV or monitor I would recommend using HDMI as it is better and easier to configure as oppose to the composite output, however if you still want to use that you can use another 4 pole to two 3 pole converter. The one that will work with Android or apple devices will also work here to. What it will do is just take in the A/V signal and give out separate stereo audio and composite video. In case of using the same jack with laptop's combo port or phone you will get stereo audio out and microphone in. Don't fall for the HDMI cable money trap though, 5\$ one worked exactly like a 50\$ one.

6. USB flash drive.

If you are plan on using NAS or Media Center or maybe RetroPi gaming setup, you might need this. Don't bother with USB3.0 however because ports on Raspberry Pi2/3 are of USB2.0 standard.

7. An analog game controller.

If you plan on using RetroPi this is a must for you. You can get either the wired one or wireless one.

8. (under construction)