So i have an arduino and a fan the both are on a 12V power supply.
But the arduino has a resistor between the power supply and itself to prevent it from burning.
Using my arduino i want to switch the fan on. But which transistor should i get?
I heard that i should get BC337. But when i order it i received the wrong values.
I have S8050, S8550, S9012, S9013, S9014, 2N3904, 2N3906, A1015, C1815, 13001.
Could i use on of those to switch my fan on and off?
How much current does the fan take?
Oh yeah sorry forget about that 12V about <0.5A.
dennis_arduinouser:
I heard that i should get BC337.
I looked at the BC337 datasheet, and with a 0.7V VCE, it's not that great of a switch.
The 2SC6097 is an inexpensive medium power transistor with a low VCE at currents as high as 2 to 3 Amps, and a high current gain, which makes it good for driving moderate levels of current, with a 20mA base current, allowing the Arduino to do some decent work. It's also a fast transistor.
dennis_arduinouser:
But the arduino has a resistor between the power supply and itself to prevent it from burning.
Waitaminute.........wut?
Who told you to do such a thing?
INTP:
Waitaminute.........wut?
Who told you to do such a thing?
That, actually, can make sense. It distributes the power loss away from the regulator chip (on the Arduino). One of the things that limits how much current can be drawn from the Arduino 5V pin, is how hot the regulator gets. There are two things that cause the regulator to get hot: Voltage Drop (or "Dropout Voltage") and Current. Basically P=IE.
By adding a resistor in the Vin line (i.e. between the power supply and the regulator input), in cases where the input voltage is larger than the regulator's dropout voltage, causes some of the voltage to be dropped across the resistor, and thus, NOT across the regulator. Doubly thus, less power dissipation in the regulator. Tripley thus, the regulator gets less hot. Quadruplly thus, higher currents can be drawn through the regulator, up to it's internal limiting value ('cuz it both limits current AND shuts down if it gets too hot)
BUT, I'm not sure if even at 12V in, if heat protection will happen before current limit, or not. So, that would be the determining factor as to whether this is a dufus move of not. But, then, there is another possible reason for distributing heat away from the Arduino: what if the Arduino is an a heat sensitive area? Using the resistor in the power line would be an excellent way of moving some of the heat away from the Arduino.
Oh, and in case you missed, this: there is an existing 12V source -- and thus the reason why this person probably would not consider using a lower voltage, as an option.
Not the point of my confuzzlement. I get the point of why someone would put a resistor there. I just don't think it's a good way to drop voltage. It's just making heat. And if it was done with some notion of preventing something from burning, well, it's a poor plan. Think it's a penny resistor with a current rating too low? I think that'd be likely the case.
INTP:
Not the point of my confuzzlement. I get the point of why someone would put a resistor there. I just don't think it's a good way to drop voltage. It's just making heat. And if it was done with some notion of preventing something from burning, well, it's a poor plan. Think it's a penny resistor with a current rating too low? I think that'd be likely the case.
Well, the regulator, on the Arduino, which is a Linear Regular, just "makes heat". So, is that also not a good way to drop voltage? "Good" or "Bad" is wrapped up in the requirements. To just make the pat statement that something is "Good" or "Bad", without considering the application, is meaningless.
And, could dennis_arduinouser have merely meant to prevent it from getting too hot? I mean "burning" is kind of ambiguous. If he/she had said "burning out" that would be more clear. Some people use the term burning to mean "getting hot". AND, since the 12V supply is Infrastructure, then "making heat" external to the Arduino, isn't so far fetched.
Use a buck. The end.
INTP:
Use a buck. The end.
A resistor is cheaper -- and perhaps, more reliable. You don't always have to use a leaf blower when a broom will suffice.
Haphazard resistor more reliable than a purpose built buck? Fat chance.
I have a cig/acc socket to USB adapter plug sitting in my car. 12V to 5V adapters are literally as available as bubble gum, sitting at the counter of a gas station.
My question remains. Where is this advice to use a resistor on a power supply line coming from? I must not have crossed that part of the internet yet.
INTP:
Haphazard resistor more reliable than a purpose built buck? Fat chance.
I have a cig/acc socket to USB adapter plug sitting in my car. 12V to 5V adapters are literally as available as bubble gum, sitting at the counter of a gas station.
My question remains. Where is this advice to use a resistor on a power supply line coming from? I must not have crossed that part of the internet yet.
Switch mode supplies are notorious for failing. And no wonder -- their components are put through the wringer 
The more complicated a system, the more can go wrong. A properly selected power resistor is a simple and robust system.
Yes, there are cases where an SMPS makes more sense, but this, really, isn't one of them.
...so, not "The End"...?
ReverseEMF:
I looked at the BC337 datasheet, and with a 0.7V VCE, it's not that great of a switch.
The 2SC6097 is an inexpensive medium power transistor with a low VCE at currents as high as 2 to 3 Amps, and a high current gain, which makes it good for driving moderate levels of current, with a 20mA base current, allowing the Arduino to do some decent work. It's also a fast transistor.
I use a resistor between the 12V supply and the arduino to prevent it from burning since 12V is the max it can handle i just want to bring it down a few volts. And then let the arduino do the rest.
Thanks for all the replies
dennis_arduinouser:
Is this one good? Since it has number behind it in the title.
https://nl.aliexpress.com/item/10-stuks-partij-2SC6090-C6090-TO-220F-nieuwe/32848441771.html?spm=a2g0z.search0104.3.21.6a3849b3MEwmGr&ws_ab_test=searchweb0_0%2Csearchweb201602_4_10152_10151_10065_10344_10068_5722815_10342_10343_10340_5722915_10341_5722615_10697_10696_10084_10083_10618_10304_10307_10301_5722715_10059_5723015_10534_308_100031_10103_441_10624_10623_10622_5722515_10621_10620%2Csearchweb201603_25%2CppcSwitch_5&algo_expid=78518d46-c8d1-453e-94e7-f502b6c8aa72-3&algo_pvid=78518d46-c8d1-453e-94e7-f502b6c8aa72&transAbTest=ae803_2&priceBeautifyAB=0I use a resistor between the 12V supply and the arduino to prevent it from burning since 12V is the max it can handle i just want to bring it down a few volts. And then let the arduino do the rest.
Thanks for all the replies
Wasn't able to get that link to work by Copy/paste [and I ain't gonna type it] Trying using the Link tool.
Link seems to work.
10 pieces / lot 2SC6090 C6090 TO-220F new
No idea what that part is.
CrossRoads:
No idea what that part is.
A high voltage transistor for the horizontal deflection stage of a TV.
It needs 100mA base current for 500mA collector current.
Totally unsuitable for this.
Since the link was in Dutch, I suggest something like the BD135 (common there).
Use a 220ohm base current limiting resistor with that one.
Leo..
Wawa:
A high voltage transistor for the horizontal deflection stage of a TV.It needs 100mA base current for 500mA collector current.
Totally unsuitable for this.Since the link was in Dutch, I suggest something like the BD135 (common there).
Use a 220ohm base current limiting resistor with that one.
Leo..
Have a look at this post, where I teach how to determine this for yourself:
https://forum.arduino.cc/index.php?topic=540188.0
Then, if you have questions about that, I, or perhaps someone else, will be happy to answer those. That way, you don't have to rely on other people to verify a transistor selection -- you can do it all by yourself. [I mean, you *do* realize, unless we are familiar with the particular transistor you present to us for evaluation, we will, probably, have to *look it up ourselves*, then do our best to provide you an evaluation based on a *limited view* of how you plan to use it. That takes time and effort. And, *I, for one, am not willing to do that.*]
Learn how to do it for yourself ;D
Yes, that is the part Leo recommended. The correct summation of the other thread can be distilled down to one sentence:
“In saturation you need the base current to be about 5 to 10% of the collector current for a BJT”
Thank you, MarkT.
avr_fred:
“In saturation you need the base current to be about 5 to 10% of the collector current for a BJT”
Maybe for that BJT. Otherwise, there's more to it than the mere base to collector current ratio (i.e. the Beta) -- such as, power dissipation in the transistor, Breakdown Voltage, ability of the Arduino to supply enough current to drive the transistor. Perhaps, even, switching speed -- especially if PWM is involved.