<p>Any 5&nbsp;V "output" on those main boards would be used to power a USB host. This is because the electronics actually runs on 3.3 volts. It would be better to splice the input power (the 12 to 24&nbsp;V) and use a buck converter to get down to your required 5&nbsp;V. Select the right one, and you can have all the current you need. </p>

CC BY-SA 4.0
2020-05-22T13:34:56.920Z
2020-05-22T13:36:03.090Z
2020-05-22T13:36:03.090Z
user77232
<p>Any pin that is labeled as "5&nbsp;V" can supply the full amount of current. Looking at, for example, the <a href="http://domoticx.com/wp-content/uploads/2016/05/Arduino-MEGA-pinout.jpg" rel="nofollow noreferrer">Arduino MEGA pinout</a>, we can see several pins labeled in red with "5&nbsp;V". These are the pins you can use. Most 3D printer boards will expose the 5&nbsp;V pins at several points. For example, the endstop connectors often have a 5&nbsp;V pin that can be used.</p>

<p>The pins that are limited to 40&nbsp;mA that you are thinking of are the digital pins, i.e. the pins that can be switched on/off by the microcontroller. These are actually more limited than this, and while in some cases drawing 40&nbsp;mA from them may be possible, it is not a good idea.</p>

CC BY-SA 4.0
2020-05-22T14:13:05.923Z
I have confirmed this. I was confused because I had a fairly common two pin solid state relay (SIGNAL, GND only). And it  could work on the constant 5V pins, but not on the digitally controlled pins, probably because there is less current on the latter, even when the signal is set to high. It is annoying because it can't be digitally controlled unless i add another mechanical relay (defeats the purpose of using a solid state relay) or if I use it at a 12V extruder port (one less heater)
K Mmmm
CC BY-SA 4.0
2020-05-22T07:54:55.030Z
2020-05-22T13:35:00.220Z
2020-05-22T13:35:00.220Z
Tom van der Zanden
<p>Typically in Arduinos, most of the 5&nbsp;V outputs that have a limited amount of current (40&nbsp;mA). </p>

<p>Are there any 3D printer boards, or is there even a more usual spot, where you can get a 5&nbsp;V output that isn't capped by the microcontroller?</p>

<p>I know that USB 2.0 is (typically) limited to 500&nbsp;mA especally when connected to a laptop. Just wondering if there was a way to for e.g. get a 200&nbsp;mA output from one of the 5&nbsp;V pins, or more if there is a stronger power supply connected to the USB port. </p>

CC BY-SA 4.0
2020-05-21T20:39:46.790Z
I believe the USB port is generally a “device” port, which will not supply power, as opposed to a “host” port, such as on a PC.
DoxyLover
CC BY-SA 4.0
2020-05-22T14:24:47.343Z
That's true and one interpretation of what I said, but i still meant if you had a 3D printer board powered only by USB and not 12V, is there a pin somewhere on the board to get more of the 5V power from the USB?
K Mmmm
<diy-3d-printer><electronics>
Access uncapped 5 V output on 3D printer controller board
K Mmmm
# Access uncapped 5 V output on 3D printer controller board

(Asked by: username_0 on 2020-05-21)

Typically in Arduinos, most of the 5 V outputs that have a limited amount of current (40 mA).

Are there any 3D printer boards, or is there even a more usual spot, where you can get a 5 V output that isn't capped by the microcontroller?

I know that USB 2.0 is (typically) limited to 500 mA especally when connected to a laptop. Just wondering if there was a way to for e.g. get a 200 mA output from one of the 5 V pins, or more if there is a stronger power supply connected to the USB port.

**Tags:** diy-3d-printer, electronics

> **Comments:**
> **username_1**: I believe the USB port is generally a “device” port, which will not supply power, as opposed to a “host” port, such as on a PC.  
> **username_0**: That's true and one interpretation of what I said, but i still meant if you had a 3D printer board powered only by USB and not 12V, is there a pin somewhere on the board to get more of the 5V power from the USB?  

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## 2 answers

### Answer by username_3 on 2020-05-22. Score: 3 | Accepted answer

Any pin that is labeled as "5 V" can supply the full amount of current. Looking at, for example, the [Arduino MEGA pinout](http://domoticx.com/wp-content/uploads/2016/05/Arduino-MEGA-pinout.jpg), we can see several pins labeled in red with "5 V". These are the pins you can use. Most 3D printer boards will expose the 5 V pins at several points. For example, the endstop connectors often have a 5 V pin that can be used.

The pins that are limited to 40 mA that you are thinking of are the digital pins, i.e. the pins that can be switched on/off by the microcontroller. These are actually more limited than this, and while in some cases drawing 40 mA from them may be possible, it is not a good idea.

> **Comments:**
> **username_0**: I have confirmed this. I was confused because I had a fairly common two pin solid state relay (SIGNAL, GND only). And it  could work on the constant 5V pins, but not on the digitally controlled pins, probably because there is less current on the latter, even when the signal is set to high. It is annoying because it can't be digitally controlled unless i add another mechanical relay (defeats the purpose of using a solid state relay) or if I use it at a 12V extruder port (one less heater)  

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### Answer by username_2 on 2020-05-22. Score: 2

Any 5 V "output" on those main boards would be used to power a USB host. This is because the electronics actually runs on 3.3 volts. It would be better to splice the input power (the 12 to 24 V) and use a buck converter to get down to your required 5 V. Select the right one, and you can have all the current you need.


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