Serial port ISP programmer

 Beginners in electronics , especially into microcontrollers normally lack a programmer for embedding the program into the controller. There is always an option go and buy one but considering the cost of making one and the purchase of  a new one, making one is easier and cheaper. This is an AVR programmer. The cost incurred to make one is about 50Rs in total cause it only involves a few resistors, a transistor ,7805 and a serial port connector.

I have made and tested this programmer circuit. The schematic is connected as shown below.

The layout is given below.

serial port ISP

In order to interface this to the microcontroller, The six pins in the layout to be connected to the six pins of the microcontroller. The pinout of the layout from the top to bottom is as MOSI, MISO , SCK, ~RESET, Vcc and Gnd. The software to be used is called ponyprog , you can download it from here for free http://www.lancos.com/prog.html.

We can also make USB programmer at home but it requires a controller in its design and for programming that controller we need a programmer.

Portable Cell Charger

This is a portable cell charger that I'm using when on short trips. Its a very simple circuit containing a USB female port, a 7805 and an LED. I use a 9V portable battery for charging my cell with the help of a USB charger.

The PCB , schema and layout are given as always.

Cell charger by

Light sensor

The light sensor senses the solar output and keeps the connected load turned off until a certain brightness of the light which can be controlled using a pot. When the brightness goes down the required value then the load is turned on automatically. The circuit uses a LDR [Light dependent resistor] and a transistor 2N3904 to detect the light and give output from the relay.

List of components:

1. Resistor: 470ohm / 1watt
2. Capacitors : 0.68uF and 47uF
3. Diodes: 1N4007
4. Zener diode: 15V, 1/2W
5. Transistor: 2N3904
6. Pot :10k , pcb mountable
7. Relay: any 5V single pole relay
8. Green connectors : 2nos [ 1for input and the other for output]
9. LDR [ light dependent resistor]

The pcb layout

Light Sensor by

The PCB operates on very simple basis, the transistor turns the relay on and off. The LDR when exposed to light actuates the relay which in turn opens the light circuit, when there is no light to LDR then the relay is deactivated which turns on the light.

The same PCB can be used for some other applications such as automatic door bell, unmanned railway crossings and many more. Make sure to connect the line and neutral in proper fashion as shown in the image above.

Note: Make an alternate wiring for the light such that in case of necessity we get to turn on the light even on day time and if possible to turn it off too.

Next to be updated

The next update would be of light sensor for most home applications.
The detector would be placed at the a proper place where the sun would be in the line of sight to detect sunlight. When in short of the sunlight , it would switch on a tubelight or else a bulb to which it is connected.

TO be UpDated in this week.

Emergency Light

The first post that I wanted to make was the Emergency light, it is an important creation for me cause this was my first ever board that I designed completely by myself.This might be of use to everyone due to the frequent power cuts these days.

The list of Components and their ratings:

1. Diodes : 1N4007 -  6 nos
2. Capacitors : 470uF, 16V -1 nos
3. Regulator : MC7805- 1nos
4. Battery : 4V, 4.5Ah - 1nos
5. Relay : 5V DC, single pole, I used Hongfa relay  1nos
6. Resistors: 1kohm,1/2W  2nos
7. LED's: Green , Red - 5mm
8. Transformer: 0-6V, 500mA secondary
9. 2 Pin male and female connectors: 4nos
10. White LED: half cut , 5V  - Quantity can be as per required..I used about 40 of them in mine.
11. Mechanical casing to fit in all the components firmly.

I have used acrylic box to fit the PCB, the red light when the power is not there can be seen in the above image.

The operation of the circuit is very simple. The diodes convert the input AC voltages to DC , the capacitors remove and regulate the ripple, the regulator takes care of the voltage step down in case of surges.The regulator is connected to the battery such that it only gives power to the battery.The relay inputs the ac power and keeps itself on whenever there is power.In case of power loss, the relay deactivates itself letting the battery power the led's. 

The PCB layout for my design has been attached to this post.

Emergency light by Dheeraj Sonnenahalli

Upgrades :

Changes in battery can be made , if in case higher voltage battery is used then connection of led's in series would help.Also dont forget to replace the voltage regulator [7805] with the battery rated one (remember to use the regulator about 2V higher voltage rated than in battery) and also the transformer with rated voltage and current.

The begin

I found some really interested people in electronics and embedded systems recently at my college, watching them I thought how many more would be there without proper availability of resources. I was such a couple of years back and still beginning to learn. This blog was inspired by many of my friends who continuously fussed me upon putting up a blog for myself and even are doing it now, I thank you all for the inspiration.

To describe the blog, it will be posted with some useful tips and tricks on designing , printing and fabrication of PCB's towards conventional electronics and also digital electronics.My contact details have been provided on my profile. I would love to help people out on their projects, hobbies and other stuff so feel free to contact me.

Thanking you all,
Dheeraj