35mA led with 25mA pic output?

[xnihilo]

I have no 5v 10mA led left and the only led i have is 2v 35mA and I have to use that with a pic which can output maximum 25mA per pin. What will happen??

Something else. The piezzo buzzer i use is 3-12v continuous tone, 9mA. 9mA for what voltage??

Thank you if you can explain this to me.

[duncan303]

I have no 5v 10mA led left and the only led i have is 2v 35mA and I have to use that with a pic which can output maximum 25mA per pin. What will happen??

Hi, can you say what you THINK might happen,


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[xnihilo]

Hi, can you say what you THINK might happen,


____

Led will glow dimmer...?

[aratti]

Place a 220 ohms resistor in series to your led. If you want it brighter, then you should use a transistor. Your beeper can be connected directly to the pic output.

Al.

[J. Mark Wolf]

You'll compromise the integrity of the pin trying to draw too much current from it with your 35mA LED. Possibly damage the PIC.

Put a transistor in the circuit.

[Nicmus]

Hi Xnihilo,

If you want to keep the full LED brightness you must use some sort of buffer (a small NPN or PNP transistor or a low power N or P channel FET or MOSFET will be your best choices) combined with a 82 Ohm resistor for your 2V 35 mA LED.
If you don’t mind loosing some brightness a limiting resistor (in your case 120 Ohm will give you 25 mA or 150 Ohm will give you 20 mA).
All you have to do is trying and decide.

Regards,

Nick

[Acetronics2]

Hi,

Two paralled-trough-180 Ohms-resistors pins will do it ...

simple way.

Alain

[xnihilo]

Hi Xnihilo,

If you want to keep the full LED brightness you must use some sort of buffer (a small NPN or PNP transistor or a low power N or P channel FET or MOSFET will be your best choices) combined with a 82 Ohm resistor for your 2V 35 mA LED.
If you don’t mind loosing some brightness a limiting resistor (in your case 120 Ohm will give you 25 mA or 150 Ohm will give you 20 mA).
All you have to do is trying and decide.

Regards,

Nick

I understand i should use the 5v power supply with a 82 ohms limiter and switch led with a transistor in order to have full brightness but i do not wish to add a transistor. I should then either choose an inline current limiter and chose the adequate value for let's say 20mA and have a dimmer led or get a 10mA led.
Okay, thanks all for your answers.

[xnihilo]

You'll compromise the integrity of the pin trying to draw too much current from it with your 35mA LED. Possibly damage the PIC.

Put a transistor in the circuit.

I see, the led will try to draw the 35mA it needs. The Chicago red 5v 10mA i used before were better
Thanks

[xnihilo]

Place a 220 ohms resistor in series to your led. If you want it brighter, then you should use a transistor. Your beeper can be connected directly to the pic output.

Al.

Okay, thank you but tell me, how did you calculate this 220 ohms value?

[eng.alamin]

I have no 5v 10mA led left and the only led i have is 2v 35mA and I have to use that with a pic which can output maximum 25mA per pin. What will happen??

Something else. The piezzo buzzer i use is 3-12v continuous tone, 9mA. 9mA for what voltage??

Thank you if you can explain this to me.

easy way just connect 1kohm Resistor serially with your 2v led and it will work fine

regards

[skimask]

easy way just connect 1kohm Resistor serially with your 2v led and it will work fine

You must mean like is suggested in posts #4, #6, #7, #11, #13 and a few others?
Maybe not that exact value...but...well...