Help with temp. control fan hardware

According to the datasheet posted earlier,it's like this.
Why don't you take a multimeter,connect one probe to the common anode pin and the other to the cathodes,one by one, and check for yourself.

Your approach is good ... better to clear things up beforehand,rather than learn it the hard way. :-)

hi arun...i have finally got all the components and started building ...
i have more or less completed the hardware part but 1 thing remains doubtful...
u said to connect p22 of 8051 to led cathode using 330ohm...but in the diagram it says u should connect p24 of microcontroller instead of p22... would this make any difference or is it same??
i have connected the gate of bt136 tirac to the emitter of 4n25 using 1k and connected +5dc to anode and collector of 4n25. what i m not sure about is what to connect to the remaining pins of triac.. pin 1 and 2, terminal1 and 2. i'm using a power supply with built in +12 +5 0 -5 -12 VDc. which connection goes where???? on the triac and i'm also going to use +12vDc motor.
will really appreciate ure response

but in the diagram it says u should connect p24 of microcontroller instead of p22... would this make any difference or is it same??

digital-guy

Which diagram?
In the schematic in your 1st post,Pin22 is connected to the opto...so it should be that way unless you intend to change the code.

i have finished the hardware and programmed the 8051...when i power the circuit on, the 2X dual 7seg display reads blank 0 0 9 and when i press the button for switching between auto and manual mode...it reads " blank u t o " then " blank n f f" and when i press it again " blank u t o" then " blank n blank blank". basically the first digit is not working and the other have problems either with hardware or software... i have followed the pin description given in the code e.g.
DIS_A EQU P0.2
DIS_B EQU P0.3
DIS_C EQU P0.4
DIS_D EQU P0.6
DIS_E EQU P0.5
DIS_F EQU P0.1
DIS_G EQU P0.0

DIS1 EQU P0.7
DIS2 EQU P2.7
DIS3 EQU P2.6
DIS4 EQU P2.5

PLUS EQU P1.0
MINUS EQU P1.1
AUTO EQU P1.2
AUTO_LED EQU P1.3
""
and also the display doesnt show the room temperature or allow me to amend the temperature range in the auto mode.... what am i doing wrong....please help :mad

i have a question...
how does the speed of the fan get controlled by port 22 of microcontroller. can any 1 explain the concepts of it
thankyou

simple, pin22 switches the fan "ON" or "OFF" thru the optocoupler when temp exceeds certain limit and when the temp comes down ( bcoz of the fan running cools the place) the fan is switched "OFF".


Arun

i understand this... but how can the voltage going to the fan be varied... eg how can the speed of the fan be in different levels for example speed ranging from 1- 9. how can this be done

i understand this... but how can the voltage going to the fan be varied... eg how can the speed of the fan be in different levels for example speed ranging from 1- 9. how can this be done

digital-guy

The switching happens very quickly..
power on the fan runs full speed,
power off it stops,
pulsing the power averages the speed to somewhere in between.

i can set the port to 1 (setb) to switch on or clr to off the fan... but how would i chose the speed in between or increment the fan speed

firstly digital-guy, you have not posted the full schematic of the project, on the first page you just have posted main portion but i guess( i strongly remember) that the second schematic of the project contains ZCD ( Zero Crossing Detector) built around op-amp LM358 and this is required for varying the Fan Speed.

BTW, finally what supply are you using for the fan AC or DC.

now for the speed control part,

lets assume the AC mains freq is 50Hz i,e 0.02 sec and every half cycle the i,e 0.01sec the voltage changes phase and passes thru zero state, this zero crossing input is fed to the micro thru an interrupt pin and the micro now knows that the voltage is near zero( there is delay by the time the micro responds to the interrupt) so it can be any where between 0-10volts, at this point the micro fires the triac /SCR thru the optocoupler, remember the micro has 0.01sec to fire the triac/SCR, if full speed is required then the micro fires the triac/scr immediately after the ZCD interrupt and very lately for slow speed i,e at the later portion of 0.01sec.

this how it all happens and it happens very rapidly.

for more info you can google for " Phase controlled firing of Triac/SCR" or
"AC Lamp Dimmer"



Arun