keyur's way: September 2011

September 28, 2011

Power Inverter design(Proteus Simulation)

Hello friends

Rright now I am working with induction furnace as a final year project.

As a part of that I am working on an inverter made up of H-bridge connection of Power MOSFETs.

you can read more about MOSFET triggering circuit from here.

You are reading this ,means you should also be interested in PWM control of Inverter.

Basic connection of an inverter would be as shown in figure below….

If s1 and s4 are on current through load is positive.

If s2 and s3 are on current through load is negative.

Be careful about simultaneous conduction of s1 and s2 or s3 and s4 if either are conducting simultaneously you will end up with something blown either it is fuse of lab or your own design..:(

we can come up the short circuit by "crow bar circuit"but that is not discussed here..

Now comes the most challenging work generation of gate pulses for MOSFETs.

As I know that my load(in future)is inductive in nature so I have to design it including “zero voltage freewheeling”.

The pulses that I have to generate are shown below this fig is taken from Power electronics by Joseph Vithayathi.

The method of generating these pulses is shown below.

I have used microcontroller (My favorite AVR Atmega 8535 )to generate Ramp wave.

Code to generate ramp wave of 10 KHz is given below(crystal freq is 16MHz)

include<avr/io.>

#include<delay.h>

void main()

{

DDRB=0xFF;       

unsigned char i=0;

while(1)

{

PORTB=i++;

asm("nop");

asm("nop");

}

}

Then the wave is fed to a comparator, the reference voltage is given with the help of a potentiometer user can adjust it.

you can see the pwm changing with reference to the DC level changed by user..

after connecting this stage to the Flip Flop stage we can observe these waveforms

after applying these gate pulses to MOSFET (IRF640)we can see the changing direction of current through the load branch...

the codes for generating ramp wave and ISIS Proteus design can be found from here.

that's all for this post friends next I'll post what difficulties i faced in implementing this ISIS design to reality.

feel free to comment

September 26, 2011

How to build your first robot (wired)?

When you want to build a wired your first robot with least circuitry you can go for this option.

this can be your first mini project on school level or for first year college student.

all you need to have is two motors,two DPDT switch with hold in center (that is some times referred as "rocker switch") ,and a battery.

here is the switch which is preferred.
you can get it from here

you are now ready to make your own robot that can go in all four directions...

connect the motors as directed here in figure and you are ready to "GO"

hope it is easy to implement it you can easily participate to locally held Robowars and Roborace events in which robots with wired connections are allowed...

if any question then feel free to leave a comment...

: )

Counter strike tips for spamming,peeking and money

Spamming:-

Spamming is the art of shooting your opponents penetrating through walls,doors or any other thin textures without exposing yourself.

Here are some of the general tips that one should keep in mind :

1. Concept of Double-Textures : The art of avoiding being spammed IE. whenever you take cover behind a double or more texture you wont get spammed by small weapons.

2. Concept of Silencer of Colt : Not only hides your direction and position from your enemy, it also serves the purpose of letting you hear whether or not you are spamming correctly as it itself doesn't cause much sound.

3. Concept of Spamming with sounds : Try to follow the sounds and go for intelligent guesses of your enemy positions, before you start spamming. Also go for short bursts instead of spraying enabling you to follow the "aah" sound or the bullet hitting the head sound.

4. Spam mostly when you are waiting for backup or at the beginning of the round after taking necessary cover.

5. Try not to do spamming when there are lots of enemies in front of you and you are alone, because you would never have enough emmo to kill them all.

6. Powerful weapons like awp can kill enemy through 4 textures also,so just go through overviews of every map and enjoy spamming...........

Peeking:-

Peeking is the art of cautiously popping out to check out for enemies generally from edges and corners of maps.It can broadly be classified into the following types :

1. Normal Peeking : You just strafe out the edge for a second and strafe back to cover.

2. Jiggle Peeking : You jump and strafe out the edge and strafe back mid-air to cover.

3. Crouch Peeking : 1. You crouch and move forward to peek slowly (generally to peek a higher ground).

4. You duck repeatedly to peek over a cover.

5. Jump Peeking : You jump repeatedly to peek over a cover (generally to peek higher than the crouch peek).

Money Distribution:-

1. Winning a round as CT always fetches you 3250 $ each irrespective of how you win the round--whether its a target save, whole opponent team elimination or defusing the bomb. However, as T if you win the round with the c4 blasting the team gets 3500 $ each.

2. Losing the first round fetches you 1400 $ and 500 $ (losing bonus) extra for every subsequent loss. But if your first lost round is after a win the counter starts from 1500 $. The maximum amount that you reach is 3500 $. Every bomb plant fetches each team member 800 $ (if at all they proceed to lose the round).

3. The losing bonus gets reset in either of the two ways. Firstly, if you win a round in-between. Secondly, if you save out ie. if you are not dead after losing the round. The one who saves out doesnt get the round money. However if the save out losing round is after a win, then the losing bonus doesnt get reset but the upper limit reduces to 3000 $.

4. There are two conditions where the save out doesnt count. Firstly, if you, as CT, die in the c4 blast. Secondly, if you, as T, manage to escape but the c4 gets defused.

5. Always type your balance in the freezetime before buying so that the team-leader can call whether or not to go for an eco. Also you can avoid going for a full buy when your rest of the team is broke and are probably going for an eco.

6. Always try to make your opponents save-out although aiming at reducing the no to as low as possible. When you yourself are going for a save-out keep in mind the financial condition of your team and also the gun that you are saving is really worth saving in the given situation.

7. If you have a balance of 10000 $ or above offer to buy guns fo your team-mates. Because of the fact that you can possess a max amount of 16000 $ consecutive wins wont be of much benefit. Rather buying guns for your team-mates would provide the scope of increasing the avg balance of the team.

8. If you are dropping guns for your team-mates, dont buy until you make sure that the person has no guns to drop, that you might prefer to play with. And always remember that ammo is non-tranferable.

September 21, 2011

My line follower (Programming)

Hello friends I hope you all have read my post about the sensors used in line follower..

So now it is the time to go for the logical side…..

Let us start with how actually a line is followed

According to the position of sensors we have to make a look-up table for all the possibilities….

Let us start…..

If i am using 3 sensors I can do…

LEFT SENSOR	CENTER SENSOR	RIGHT SENSOR	LEFT MOTOR	RIGHT MOTOR	comment
0	0	0	FORWARD	FORWARD	To avoid the cross…
0	0	1	STOP	FORWARD
0	1	0	FORWARD	FORWARD	Worst case!!!
0	1	1	STOP	FORWARD
1	0	0	FORWARD	STOP
1	0	1	FORWARD	FORWARD
1	1	0	FORWARD	STOP
1	1	1	REVERSE	REVERSE	Line is lost Return to line