circuit help

[ejector]

Hello everyone, i am building a "propeller led clock" i have done all the work but i am not getting which interrupter to use. i want an interrupter with 3-legs which should give me a level HIGH (5v) output all time But the output should drop to zero (LOW level) voltage when it is put near to the south pole of the magnet. can anyone name a hall-effect sensor that matches my requirement?

And please, with this, name an opto-coupler TOO, which should do the same work.like it should give me a 5v output all the time but the output should drop to 0v when anything comes between its IR.

please tell the name of both (hall-effect sensor and OPTO-COUPLER).

Thanks a lot.

 

[blueroomelectronics]

Post your schematic

 

[ejector]

here is my schematic. and tell me name or number of both hall-effect sensor as well as an opto-coupler competible with my requirements please.
Thanks

 

[ejector]

i think no buddy here can help me :-(

 

[sonuv]

I am unable to understand what are you asking?

 

[sonuv]

If you want to drop 5v to 0v then you need to use some source like 7.5v or 9v and a regulator chip 7805.this will provide you 5v.then use a transistor as a switch .to control the transistor use your micro controller.

 

[audioguru]

When RadioShack was still in Canada they sold an over-priced propeller clock. It vibrated so much that they taped the demo one to the shelf.

 

[Boncuk]

Check out the TLE4905.

It does exactly what you expect.

(works with the south pole of the magnet)

Boncuk

 

[ejector]

@ Boncuk
Thanks a lot. and can you please name an opto-coupler too with the same description?. please

 

[Boncuk]

Hi,

I don't know any optocoupler with the same description as a Hall sensor.

Here is probably what you were getting at:

Boncuk

 

[ejector]

@Boncuk
Thanks a lot for your help. i hve done my work work with DN6851 hall-effect sensor. though it does not match my requirement Because it works on alternating magnetic field But i have used it to do the same work as TLE4905, and it is doing.
My project is still in process. if i get any problem, i'll come again and will ask you for help.
Thanks agian

 

[ejector]

Hello everyone,
I have stuck on a problem agian. i have done all the work. in starting, i found that two top (blue) LEDs are not glowing and i don't why the red LED is going off when other LEDs are lighting, when this red LED is directly connect to the 5v and groung. i am including the original picture which i downloaded from a webside and mine with problem. and i am powering the circuit with my mobile charger which is giving 5.4v.i don't know about the Amp of this charger. i also am attaching schematic and .asm code file. please check it out.

Thanks

 

[audioguru]

You have 9 LEDs in parallel with no current limiting. They are a dead short to the low current output of the microcontroller. Maybe they are the top (blue) LEDs? Then maybe when the 9 LEDs short the output of the microcontroller, it turns off the drive to the red LED.
1) Use a transistor to drive the LEDs.
2) Each LED should have its own current limiting resistor.

 

[ejector]

@Audioguru
Actually i did the simulation of the circuit. The circuit is working fine in simulation. now i checked all the conections. what do you think i should check again?

1) should i use a transistor to drive the off LEDs?
2) Should i use a low value resistor with higher wattage with 9 LEDs which are parallel?

 

[sonuv]

never use parallel connection

you are using 9 led in parallel means they will eat away all current.put them in series and connect them.for more current you can use relay as switch in place of transistor.

 

[audioguru]

Your simulation software didn't read the max ratings spec's for the microcontroller on its datasheet. The max allowed current from each output is 25mA and only 50mA total at a time for the entire chip. If you want each of the 9 LEDs to have 20mA then the total is 180mA which is much too high.
LEDs are never connected directly in parallel unless they are all tested and sorted so they all have exactly the same forward voltage because they are all different. The one with the lowest forward voltage will hog all the current and be very bright or it will burn out. Then the one with the next lowest forward voltage will burn out.

You cannot connect the LEDs in series unless you have a very high supply voltage since each blue LED needs about 3.5V then 9 in series need a supply that is higher than 31.5V.

 

[ejector]

@audioguru
you were right when i checked the connections of the LEDs. i found that one of the two LEds (which were not glowing) one was shorted and the other was not blinking at all. then i repleced the bed LED and the circuit if working fine now. This was all about the digital mode of this project But when today i chaged the mode to the analog, the 9 LEDs(are in parallel) have to make the hands of the minute and the hour the 9 parallel LEDs are glowing But Very lightly. it is also may be because of some shorted LED?

 

[audioguru]

The microcontroller cannot and must not drive 9 LEDs in parallel. To be bright, each LED needs a current from 10mA to 20mA which is a total current of 90mA to 180mA. The max allowed output current from one output is only 25mA so you are risking blowing up the microcontroller. Use a transistor (with a series base resistor) to drive the 9 LEDs and each LED needs its own series current-limiting resistor.

 

[ejector]

@ Audioguru
ok i'll usa transistor to dricve these LEDs But i am attaching a picture which i downloaded from the same webside. this is analog mode of the schmatic i posted above. it's all LEDs are lighting. i want to say that when the LEDs of this project is light so why LEDs are nt lighting? when i constructed the same circuit.

 

[ejector]

and as i told you before that iam not much related with electronics so can you please tell me whch transister would be able to deliver the amount of current required in my project. what i understand is we have to increase the current from 10mA to 200mA. am i right?