EfH17 - One down, nine to go!


#1

Greetings to all the participants of the Embedded for Her program.

We hope you had a good start to Embedded for Her. Here are some resources for you with regards to the topics covered in the first session.

Videos of the topics covered in the first session:

Experiments to do at home. Please keep in mind the pin configuration of the transistor that you have. Do post photos and videos of these experiments that you do at home.

The list of components handed over in the first session:

  • Breadboard
  • Multimeter
  • Solder Gun with stand, solder lead and sponge
  • Wire stripper
  • Bluey development board
  • Stlink Programmer with Black Magic Probe software
  • Female to Male Jumper
  • Female to Female Jumper
  • Single Strand Wire
  • Electrolyte Capacitor (100uF, 16V, 10uF,16V)
  • Ceramic Capacitor (100 nf)
  • Resistor box
  • LED (5 Red, 5 Green)
  • DIP Switch (4-pin)
  • Switches - push to on, push to on push to off
  • Potentiometer (1k)
  • Motor with propellor
  • Relay
  • Diode (1N5007)
  • 2N3904 BJT
  • IRF9520 MOSFET
  • IR Sensor
  • LDR
  • General Purpose Board
  • LM7805 5V Regulator
  • Buzzer
  • 4V Lead acid Battery
  • 5 V Adapter
  • Male Berg Stick
  • Female Berg Stick
  • DC jack

#2

Some pictures from this session


#3

Those are some really nice pictures. :smile:
It looks like everyone had a lot of fun. I really missed out by not showing up, huh?
I’m looking forward to seeing the participants’ blog posts on this session, and to meeting everyone the coming weekend. :smiley:


#4

Yes, really informative session. Looking forward to the rest.


#5

HI Everyone
Was going through the videos of the topics covered in Session 1
I didn’t quite understand how to calculate the voltage of the resistor and
also how to calculate the Voltage drop of the resistor from the below video;

Also how to make use of the data sheet in determining if the usage of a heat sink is required or not from the video below:


#6

Hi Bhargavi,

In the first video, let the battery voltage be denoted by V, voltage across the resistor be V1 and voltage across the LED be V2. According to Kirchoff’s Voltage Law,
V = V1 + V2.
Given that the battery voltage is 9 V and the forward voltage of the LED is 3.2 V. Substituting these values in the above equation will yield,
9 = V1 + 3.2
V1 = 9 - 3.2
V1 = 5.8 V.

Thus, the voltage drop across the resistor is 5.8 V.

The usage of heat sink needs a detailed explanation, which will be done in person.

Thanks,
Nardhini S


#7

Hi Nardhini,

If V1 is the voltage across the resistor initially. How does it transform to voltage drop at the end of the calculation?


#8

Hi Bhargavi,
For the first video, please keep in mind that a German guy is explaining with his own quirks in his writing. For example in Germany, to represent the decimal point people use , instead of . Also in many places he writes Vr which looks like Ur and I as J.

First he shows that from the datasheet of the LED, we can see that the nominal forward voltage of the LED is 3.2V and with a current of 20 mA. (at 0.51s)

Next since he is using a 9V battery, its supply is split across the resistor and the LED. Since we know the forward voltage of the LED is 3.2V, the voltage across the resistor (which he writes as Ur) is 9-3.2 which is 5.8V. (1.38s, 1.53s)

Then in this case since the current across the resistor is the same as the LED, which is 20 mA, we can calculate the resistance by Ohm’s law. R=V/I. So we get about 290 Ohm.

This is what Nardini also explained. Since the circuit is in only one steady state, I don’t understand what you meant by [quote=“bsayee, post:7, topic:919”]
If V1 is the voltage across the resistor initially. How does it transform to voltage drop at the end of the calculation?
[/quote]

I’ll reply to the question regarding the heat sink soon.


#9

Hi Bhargavi,
About choosing the heatsink, it depends on the power that any component can withstand and you can find a temperature details of a component in datasheet. You can have a look into a characterstic curve of Power with the temperature change. There are many other factors which changes with temperature. Will discuss this in person.
To know more about heatsinks and choosing one for specific component and circuit you can go through the below link. The have explained pretty well.


And happy to see your quires here… You will be understanding hardware well with experiments.