# 0-10 VDC control voltage. Possible with automation HAT?

**URL:** <https://forums.pimoroni.com/t/0-10-vdc-control-voltage-possible-with-automation-hat/4028>\
**Category:** Raspberry Pi\
**Created:** [February 19, 2017, 12:49pm UTC](https://forums.pimoroni.com/t/0-10-vdc-control-voltage-possible-with-automation-hat/4028 "2017-02-19T12:49:24Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![yglodt](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.pimoroni.com/yglodt/32/2052_2.png) [@yglodt](https://forums.pimoroni.com/u/yglodt)\
**Post date:** [February 19, 2017, 12:49pm UTC](https://forums.pimoroni.com/t/0-10-vdc-control-voltage-possible-with-automation-hat/4028/1 "2017-02-19T12:49:24Z")

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Automation HAT’s product description states it has _3 x 24V tolerant sinking outputs_.

I have a ventilation system, and the fan speed can be controlled in 8 steps by applying a 0-10 VDC control voltage as described in the documentation:

 ![](https://us1.discourse-cdn.com/flex016/uploads/pimoroni/original/2X/a/a65465fc603563d7dfcb5a9103872c9f90b84525.png)

Can I use Automation HAT’s _24V tolerant sinking outputs_ for that?

If not, what would people suggest?

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**Author:** ![gadgetoid](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.pimoroni.com/gadgetoid/32/13_2.png) [@gadgetoid](https://forums.pimoroni.com/u/gadgetoid)\
**Post date:** [February 20, 2017, 10:59am UTC](https://forums.pimoroni.com/t/0-10-vdc-control-voltage-possible-with-automation-hat/4028/2 "2017-02-20T10:59:07Z")

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You can, but you will most likely want to bypass the Automation HAT Python library and use RPi.GPIO’s PWM functionality directly.

You will also need a 10v power supply- or possibly less if you’re not worried about achieving the maximum speed.

Is this control voltage also the fan’s power supply, or is it a separate control line? I’m guessing the former.

You would have tie the ground of your Xv power supply into the ground on Automation HAT, then connect your fan to the positive terminal of the power supply, and the fans negative terminal to the sinking output driver on Automation HAT.

I did exactly this with a PC fan on Friday.

Assuming you have a 10v supply, you should then be able to do this in Python:

```python
import RPi.GPIO as GPIO

OUTPUT_1 = 5

GPIO.setmode(GPIO.BCM)
GPIO.setup(OUTPUT_1, GPIO.OUT)

pwm = GPIO.PWM(OUTPUT_1, 25000) # Second value is PWM frequency in Hz, pick an appropriate value

pwm.start(50) # This is duty cycle in %, in this case it should supply ~5v

```

You can then use `pwm.ChangeDutyCycle(n)` to dial in values accordingly or each speed.

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**Author:** ![yglodt](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.pimoroni.com/yglodt/32/2052_2.png) [@yglodt](https://forums.pimoroni.com/u/yglodt)\
**Post date:** [February 20, 2017, 11:16am UTC](https://forums.pimoroni.com/t/0-10-vdc-control-voltage-possible-with-automation-hat/4028/3 "2017-02-20T11:16:04Z")

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Thanks for your input.

The 0-10V is only a control input (probably close to this: [https://en.wikipedia.org/wiki/0-10\_V\_lighting\_control](https://en.wikipedia.org/wiki/0-10_V_lighting_control))

I might change strategy and connect myself to the RS485 bus of the ventilation system. This way I could not only control fan speed but also read out other parameters like in-flow air temperature etc.

The ventilation device is this btw: [https://www.vallox.com/en/products/vallox\_90\_se.html](https://www.vallox.com/en/products/vallox_90_se.html)

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**Author:** ![maxsujoy](https://avatars.discourse-cdn.com/v4/letter/m/59ef9b/32.png) [@maxsujoy](https://forums.pimoroni.com/u/maxsujoy)\
**Post date:** [February 8, 2019, 4:47am UTC](https://forums.pimoroni.com/t/0-10-vdc-control-voltage-possible-with-automation-hat/4028/4 "2019-02-08T04:47:01Z")

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Thanks for the guide. I needed the same. One thing is not clear to me though, How is the Automation HAT connected to the Raspberry Pi. Pi’s BCM Pin5 (GPIO) is used for PWM but where is it connected to? Can you please help me with the wiring??

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**Author:** ![gadgetoid](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.pimoroni.com/gadgetoid/32/13_2.png) [@gadgetoid](https://forums.pimoroni.com/u/gadgetoid)\
**Post date:** [February 12, 2019, 10:56am UTC](https://forums.pimoroni.com/t/0-10-vdc-control-voltage-possible-with-automation-hat/4028/5 "2019-02-12T10:56:32Z")

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bcm5 is connected to “Output 1” on the Automation HAT:

> **[Automation HAT at Raspberry Pi GPIO Pinout](https://pinout.xyz/pinout/automation_hat)**
>
> An all-in-one home automation and control board

What this means in practise is that it’s connected to the input of a ULN2005A Darlington Array (a pair of transistors basically) so that a `HIGH` output on BCM5 will connect the “Output 1” connection on Automation HAT to ground via those transistors.

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**Author:** ![jztan](https://avatars.discourse-cdn.com/v4/letter/j/54ee81/32.png) [@jztan](https://forums.pimoroni.com/u/jztan)\
**Post date:** [August 13, 2019, 9:32pm UTC](https://forums.pimoroni.com/t/0-10-vdc-control-voltage-possible-with-automation-hat/4028/6 "2019-08-13T21:32:57Z")

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apology for renewing an old topic. But i have an question regarding to 10v supply voltage for the sinking output. I have 12v coming to run other device, can i use an 10v regulator to provide the 10v power? Something like L78M10ABDT-TR ic. I need two 0-10 channel output for an led light control. Each channel only need round 50ma to run.

Or if there other better suggest that will be great. I want to keep the project box as small as possible and an normal dc-dc buck seem a bit over kill.