light emitting diode control differ controls

[venkates2218]

what type of mosfet i have to use if i want to control positive voltage mean...?
sorry iam new to mosfet.

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irf3250 type need only 5v drictly from MCU.?

 

[Easyrider83]

irf3250 type need only 5v drictly from MCU.?

Obsiosly. Okado just need to say something.

 

[Okada]

In this circuit

https://electronics.stackexchange.c...-driver-for-mosfet-irf540-and-microcontroller

you can increase the 2k resistors to 10k. This will decrease the current through 2N3904 and reduces the dissipated heat. Mosfet doesn't need current to turn ON. When 2N3904 is ON the gate of the mosfet sees some 0.4V and when 2N3940 is off gate of mosfet sees 12V. So, mosfet conducts when transistor is OFF.

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I can understand it is difficult to obtain good components in India. Sometimes one has to pay 40 USD shipping charges at mouser.in to buy 2 or 3 USD components.

Find attached circuit which I made.

Updated circuit and Proteus file attached.

 

[Easyrider83]

Facepalm!
First you say that there difficult to buy some components in India. But then you providing schematics where more that half components can be reduced. I don't get your way of thinking.

 

[KlausST]

Hi,

what type of mosfet i have to use if i want to control positive voltage mean...?

Okada...are you aware that your given circuits show "low side switching" only?
But the OP asks for switching positve voltage which is called "high side switching".

Klaus

 

[Okada]

He just needs 3 switchs. His And configuration is not needed. He just want to turn ON/OFF mosfet normally and also to control the brightness using PWM if required.

So, He can use two buttons, one which toggle the PWM duty between 0 and 255. In the circuit I have provided. 0 meand full ON and 255 means full OFF.

Another two buttons he can use to increment or decrement the brightness.

He is new to embedded electronics and that's why he is talking about AND switches which is not needed. As he is using a MCU he can do it with just one MCU pin.

Let the OP answer after reading this. All he need is a switch.

 

[KlausST]

Hi,

Let the OP answer after reading this. All he need is a switch.

Don't you see that you answers what the OP should answer.
It's just guessing what you do.

But it seems you are aware that you provide a low side switching circuit while the OP asks for high side switching.
I'm not sure the OP knows the same.

It happens repeatedly that you provide wrong informations.
Therefore I request on you - if you are aware that the given solution is not exactely what the OP reqested - then add a description explaining the difference.
Then the OP has the chance to follow your assumptions and may decide on his own if it is usefull for him or not.

In case you have additional information (besides this thread) then remember that this is a forum. The informations are not for the OP only but for all other members and guests. They should be able to follow the discussion and gain helpfull information from it.

Klaus

 

[Okada]

Ok. If the OP stills need a circuit of high side switching then I will post one.

 

[venkates2218]

i need to switch mosfet by positive voltage from controller....
N-Channel mosfet is suitable for it..?

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mosfet need 12v to for switching means shall we use UL2003A t switch mosfet.?

 

[Easyrider83]

Let's start from beginning. What type of load and what current it take that you wanna switch? What is the frequency expected?

 

[venkates2218]

its filament type bulb with 12v/6w power...
500mA current will...
The starting current may be higher than it...

Frequency may vary at particular time interval i can't say any fixed values...
I'm using PIC16F886 to generate pulse...

I need to control the bulb on positive side from supply...so i need mosfet like PNP tpye transistor...
For supply i'm going to use 12v dc battery with 7A

 

[Easyrider83]

RT9711 good enough?

 

[venkates2218]

its not available in market...
IRF540 i ok..?

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is this is correct..?
in one logic input we can give 5v to make logic 1
on another input if we give PWM pulse...

Whether this circuit will work..?
If it work means its possible to get output based on pulse given as input..?

 

[Okada]

How do you actually want to control the device. Explain each mode with an example.

 

[venkates2218]

already i mentioned the rating of bulb...

1.I need to switch ON OFF the bulb.
2.The bulb have to work under PWM pulse also.
3.If I switched ON the bulb means only it have to work even their is an PWM also means...
4.Need to control bulb on positive side by using PNP transistor like...


my ideas to this project...
AND can be used for this...
If A is 1 means also it need an another input...
The another input is driven by pwm pulse...

If i need to switch off the bulb even their is an PWM pulse means we can make A logic to switch of the bulb...

MY DOUBT:
1.Does AND gate will work as i mentioned...
2.Is IRF540 if suitable for it..
3.If IRF540 is suitable means it will work under 5v from MCU to gate..?
4.If IRF540 is PNP type means we can done this by placing an another npn transistor before moseft..
5.To drive moseft shal we use uln2003a..?

 

[Okada]

Are you new to embedded programming ? Are you going to write the PWM control code ? Do you know if you just want to turn ON/OFF and also want to control the brightness then you can d it with micrcontroller without AND gate.

If you want this

I control pin to turn ON/OFF the Mosfet and another pin for PWM then you need OR gate. When there is not PWM then PWM input pin of OR gate will be 0 and the other input pin of OR gate can be used to turn ON/OFF the the Lamp normally. When PWM has to be used for brightness control then irrespective of ON/OFF control pin you can use just the PWM input pin of OR gate to control the Lamp brightness.

 

[Easyrider83]

Looks like you need 'OR' logic, not 'AND'.

 

[venkates2218]

what about mosfet..?

 

[Easyrider83]

There are no easy way to use n-channel mosfet at high side switching. That's why I keep silence about your idea to use it. Anyway, I don't see any problems to use p-channel mosfet. Almost any of them will fit.

 

[venkates2218]

There are no easy way to use n-channel mosfet at high side switching. That's why I keep silence about your idea to use it. Anyway, I don't see any problems to use p-channel mosfet. Almost any of them will fit.

if we using p-channel mosfet means can drive the bulb like by using PNP transistor..?