circuit wiring

Project code:-E65 Project Cost:- INR:- Rs.12000/- USD:- 300$

With
the advancement in technologies in wireless communication many
products are available in the market to make the human life more
comfortable. One of my friend asked me to design a project for him .His
only requirement was to switch ON/OFF his irrigation pump ,which is
two km away from his house. I could not find the radio module which
could cover this distance So I decided to design sms controlled
project. I used sim300 gsm module which is readily available in the
electronic market. His only requirement was to switch ON/OFF single
pump, and feedback via sms whether the pump has actually switched ON
or not.

Sms Controlled Multipurpose Isolated I/O board 8 output / 4 input Block Diagram
I
designed a relay circuit using 89c51 microcontroller Which could be
switched on by single mis call to the device and can also be switched
off by another miscall. It saves my talktime and money. I used to get
the sms from the moter starter contactor panel when it actullay
becomes on, that gives me confirmation that the motor is on.
Then
it gave me a thought to design the present project which could be used
in various application areas depends upon the individual requirement
in the field of agriculture
,lighting,security,telecommunication,access and safety both
industrial,commercial and in residential area.
Designed for control
and sensing applications, this project provides 8 relay outputs and 4
optically isolated inputs. It can be used in various applications
including load contact closure and external voltage sensing.
Connection to the isolated inputs and relay outputs is via “pluggable
type” screw terminal blocks The project presented here is based on
world’s most powerful intel’s mcs-51 family of microcontroller atmel
at89c51.In this project we are using AT 89C2051
microcontroller,since this controller has two ports are more than
enough for our project
Application area: the project can be used for various application wherever you require control using pc.
1 hotel power management
2.street light management
3.home automation
4.load shedding
5. High voltage grid control
6. Industrial automation
7.electro,hydrolic and pneumatic valve control
8. Robotic control and many more All the above operation are possile from the any mobile phone by sms
The
circuit is connected to gsm modem through rs232 cable to Dshall 9 pin
connectror connected on both sides. ic max 232 is a level conver
ter ic to convert ttl level data to +12v and –12v level for complete
details on this ic, refer to manufacturer’s data sheet
Port 3.0 is rxd pin to receive data serially and port3.1 is to transmit data serially
Circuit is driven by 9v 1 AMP transformer connected to pcon1
Diode d1-d4 forms bridge circuit c1 ,c2,c3 and c4 are filter capacitors
Ic1
7805 is 5v regulator ic to give stablised supply to
microcontrollerLD1 LED is a power indication led. Crystal gives the
necessary clock to micro-controller.
diodes d1 to d4 are power
recifire diodes connected in bridge circuit c1 is a filter capacitor
.input to the bridge rectifire is 9v 1 ampere transformer. Out put of
the bridge rectifire and capacitor is 12v dc. All our relays are
operated by 12v dc. Relay output can be connected to any 250v 7 ampere
load.please donot cross this limit other wise you will damage the
relay circuit.
Ic2 is atmel at 89c2051 microcontroller. It has two
ports port1 pin number 12 to 19 and port 3 pin number 2,3,6,7,8,9 and
11. This controller has inbuilt uart(universal
synchronous,asynchronous receiver transmitter, and pin no 2 is rx pin
and pin number 3 is tx pin of the uart. Through these two pins
micro-controller is able to communicate with the ibm pc comport.
Communication boud rate is 9600 bits per second.
Port 1 controlls all our relays.out put of this port is pulled high through pullup resistors
sil
arrays(single in line resistor array) hense the outout of pin no 12
to 19 are by default high( at 5v logic) ALL relays stays off on power
up. All the relay driver circuits are similar I will explain one
of then here .
Q1 to q16 all are npn general purpose transisters.
Npn transister will become on when base is high. If you refer circuit
diagram q1 base is driven by r3 connected to pin no 12 of the ic2 as
this pin is at logic high , q1 is on(conducting) and it’s collector
remains at low logic(transister acts as switch,very low resistance
between emitter and collector),resulting base of the transister is low
and transister q2 is in off state(non-conducting). To switch on Q2,
we have to switch off q1. To switch off the q1 the program inside the
micro-controller must bring the logic at pin number 12 to low logic.
q1 will become off and q2 base will get high logic through r4 and
will become ON. relay coil of rl1 will get energised as the current
will pass through coil , q2 transister collector and emitter to
ground. Normally open contact will close the connection. Load should
be connected to the out put of the contacts on CON1.diode d5 connected
across the relay coil is to proctect the circuit from the induced emf
generated by the relay coil during on/off operation.ld2 ic relay ON
indication led r5 is a voltage dropping resistor.
All the relay circuit works in the same manner.
Ic3
max 232 ic is a level converter ic. IBM pc com port is designed for
telephone network which works on 12v dc where as our controller logic
is at 5v we need to convert this data to +12 &-12 logic before it
is sent to pc this ic has transreceiver level converter. Transmitter
part
convert the TTL logic to com port logic and receiver part convert the
signals coming from pc to TTL level before it is given to
micro-controller.
All the components connected around this ic is as per the application notes given in the datasheet by the manufacturer..
Capacitor
c5 and r1 gives the required reset pulse to microcontroller.Crystal
x1 along with capacitor c6 and c7 gives the required clock pulse to
microcontroller.
Resistances connected to indication leds are current limiting resistors.
Four
isolated inputs are connected through opto couplers ic4 to ic7.
output of the opto-coupter are connected to p3.2,p3.3,p3.4 and p3.7
respectively. In1 to in4 are connected to the normally open contact of
the device(sensor controller) you want to monitor . when ever contact
is made led inside the opto coupler will glow and collector inside
will pull the microcontroller pin to logic low, this is the active
state of the device. You can test this by shorting in1 to in4 pins by a
piece of wire and give command from your computer you will get the
proper response as mentioned in the command section.
OPERATION
To
switch on devices, You can send sms to the device as ON1,ON2,ON3
and so on .T0 switch off devices send sms as OFF1,OFF2,OFF3 and so on .
to get the response from the actuating device if connected to the
input terminals you will receive sms on your mobile phone like
‘device1 is on’ or ‘device2 is off ’ etc.
Commnication between
SIM300 modem and microcontroller takes place via serial port Using
Sim300 AT command set. Which can be downloaded from the official
SIMCOM site.
Some are given here ,can be tried on pc using hyperterminal.
SIM300 AT Command Set
SMS commands
Demonstration Syntax Expect Result
Set SMS system into text mode, as
opposed to PDU mode.
AT+CMGF=1 OK
Send an SMS to myself.
AT+CMGS=”+861391
818xxxx”
>This is a test
+CMGS:34
OK
Unsolicited notification of the SMS
arriving
+CMTI:”SM”,1
Read SMS message that has just arrived.
Note: the number should be the same as
that given in the +CMTI notification.
AT+CMGR=1 +CMGR: “REC UNREAD”,
“+8613918186089”, ,”02
/01/30,20:40:31+00”
This is a test
OK
Reading the message again changes the
status to “READ” from ”UNREAD”
AT+CMGR=1 +CMGR: “REC READ”,
“+8613918186089”, ,
“02/01/30,20:40:31+00”
This is a test
OK
Send another SMS to myself. AT+CMGS=”+861391
818xxxx”
>Test again
+CMGS:35
OK
Unsolicited notification of the SMS
arriving
+CMTI:”SM”,2
Listing all SMS messages.
Note:”ALL” must be in uppercase.
AT+CMGL=”ALL” +CMGL: 1,”REC
READ”,”+8613918186089”,
, “02/01/30,20:40:31+00”
This is a test
+CMGL: 2,”REC
UNREAD”,” ”,”+861391818
6089”,
, “02/01/30,20:45:12+00”
Test again
OK
Delete an SMS message. AT+CMGD=1 OK
List all SMS messages to show message
has been deleted.
AT+CMGL=”ALL” +CMGL: 2,”REC READ”,
“+8613918186
089”,”02/01/30,20:45:12+00
”
Test again
OK

The common problem with many low cost inverters is their incapability of adjusting the output voltage with respect to the load conditions. With such inverters the output voltage tends to increase with lower loads and falls with increasing loads. The circuit explained here can be added to any ordinary inverter for compensating its varying output voltage conditions in response to varying loads.


The circuit was requested to me by one of my friends Mr.Sam, whose constant reminders prompted me to design this very useful concept for inverter applications.

The load independent/output corrected or output compensated inverter circuit explained here is quite on a concept level only and has not been practically tested by me, however the idea looks feasible because of its simple design.

If we look at the figure we see that the entire design is basically a simple PWM generator circuit built around the IC 555.

We know that in this standard 555 PWM design, the PWM pulses can be optimized by changing the ratio of R1/R2.

This fact has been appropriately exploited here for the load voltage correction application of an inverter.
An opto-coupler made by sealing an LED/LDR arrangement has been used, where the LDR of the opto- becomes one of the resistors in the PWM "arm" of the circuit.
The LED of the opto coupler is illuminated through the voltage from the inverter output or the load connections.
The mains voltage is suitably dropped using C3 and the associated components for feeding the opto LED.
After integrating the circuit to an inverter, when the system is powered (with suitable load connected), the RMS value may be measured at the output and the preset P1 may be adjusted to make the output voltage just suitable enough for the load.
This setting is probably all that would be needed.
Now suppose if the load is increased, the voltage will tend to fall at the output which in turn will make the opto LED intensity decrease.
The decrease in the intensity of the LED will prompt the IC to optimize its PWM pulses such that the RMS of the output voltage rises, making the voltage level also rise up to the required mark, this initiation will also affect the intensity of the LED which will now go bright and thus finally reach an automatically optimized level which will correctly balance the system load voltage conditions at the output.

Here the mark ratio is primarily intended for controlling the required parameter, therefore the opto should be placed appropriately either to the left or the right arm of the shown PWM control section of the IC.

The circuit can be tried with the inverter design shown in this article.

Parts List

R1 = 330K

R2 = 100K

R3, R4 = 100 Ohms

D1, D2 = 1N4148,

D3, D4 = 1N4007,

P1 = 22K

C1, C2 = 0.01uF

C3 = 0.33uF/400V

OptoCoupler = Homemade, by sealing an LED/LDR face to face inside a light proof container.