trying to build a robotic bartender

Hey folks... I'm planning to build me an arduino powered drink dispenser... ideally to pour shots of scotch, etc by voice command, but starting this in phases. This is my FIRST arduino project so was planning the following steps... please feel free to poke and prod me in different directions if you have experience with the board.

Design idea was to present either 4 or 8 separatory funnels with various liquids (hypothetically, vodka, scotch, gin, cold brew, etc etc) I like the look of a chemistry set and it's going with the steampunk/industrial man cave I'm building.

Each funnel was stoppered with a solenoid and then connected through a flow meter

Idea was to trigger each solenoid to open for a specific volume of liquid and then close when the volume was accomplished.

I could use some help with fundamental electrical engineering. standard disclaimers... I'm not an EE at all, and am learning through this process. That being said, I don't think i have the wiring done right between my arduino, my relay and my powersupply.

Notes to accompany the diagrams:

  • Arduino is powered and synched to computer
  • 12v 5a power supply is supposed to be powering the relay
  • 5v from arduino is going to 5v on relay board
  • grnd from arduino is going to ground on relay board
  • digital 2 pin (OUTPUT) is connected to port 1 on relay board
  • in relay board, VCC is jumped with JD-VCC
  • 12v power supply black is going to solenoid blue
  • 12v power supply red is going to terminal 3 on port 1 on relay board
  • solenoid yellow is going to terminal 1 on port 1 on relay board

What I see happening:

  • when code is sending a LOW signal on pin 2, I hear a click on the relay board, but the solenoid doesn't move
  • i can directly connect the solenoid to the 12v power supply and the solenoid is working fine.

This is the relay board I'm using: 8-Channel 5V Relay Module for Arduino Raspberry Pi –

Feel free to call me a noob and get me past this basic stop :slight_smile:


Hello there! For this forum to help you the most, you'll want to also include your current code and circuit diagram in your post.



Use the forum Google search function in the upper right of this page to search for the key words of your project. You will probably find many similar previous project discussions and code to get you started.

Dunno. May be missing critical design elements.

Welcome to the Forum.

Have you looked at peristaltic pump, they are designed to meter out fluids in food and medical situations.
A pump for each ingredient and timing for dispensing the needed amount.
No relays are required due to the construction of the pump.

google peristaltic pump arduino barbot

google peristaltic pump arduino barbot youtube

Tom... :slight_smile:

This has come up several times before. Check this thread: Drink Mixer (precise liquid dispensing) - Project Guidance - Arduino Forum

@englishscone - I was attempting to but got a block that I was posting too frequently.. I must have fat-fingered something. Will upload shortly

@zoomkat, @tomGeorge and @WildBill.. i spend ages reviewing and researching these, but my sadist side of me took over and I wanted to try to build something different. I want to use this as a learning-by-making mistakes thing.

  • I was trying to avoid pumps just so I can have something on display and something gravity fed.
  • I was hoping to use open/close solenoids to control fluid flow - ultimately I want to introduce a low meter to measure liquid amounts
  • I was also hoping to have the first pumps all flow into a mixing chamber which then "stirred" the liquid and then another valve opened to dispense into the glass.

All those reasons kinda summed up to coming up with a design and trying it.

I've watched the inebriator obsessively for a few weeks and wanted to avoid the motor going back and forth mostly for aesthetic reasons. I think it's super badass, but just didn't want to go that way.

My first mistake was a wiring/circuit mistake and would love to understand what happened and how to fix it.

stand by for circuit diagram and code :slight_smile:

PS - @Paul__B - if it ain't on Amazon Prime, it's safe from me.

"@zoomkat, @tomGeorge and @WildBill.. i spend ages reviewing and researching these, but my sadist side of me took over and I wanted to try to build something different. I want to use this as a learning-by-making mistakes thing."

You will probably find that many will not be interested in your project adventure if you don't do your own homework up front and have some "skin in the game" as they say. Do read the "Read this before posting a program question..." at the top of the discussion list to get started off on the right foot.

The problem with gravity feed is that you probably have insufficient pressure to power a flowmeter, so therefore your problem is how to measure out correct amounts. The best you could do would be to have a servo operating "shot" dispensers, whether they are the common manual type or your own invention.

I think a peristaltic pump - again whether a commercial type or your own invention - would be sufficiently "visual". :grinning:

@zoomkat... I hope I didn't mis-state ... I have been reading and understanding those projects. I really hope I am taking and learning what they've done. I'm just more driven by the learning process than necessarily the outcome of building what has been built before. I learn more by trying and failing vs. observing and learning. My skin in the game is my sweat and my desire to understand this world more.

@Paul__B... I'm beginning to see that. The plastic pumps (that require a minimum pressure to activate) won't work unless I have a 7 foot tall column of liquid... that's not happening. I've since moved to a brass solenoid which doesn't require any minimum pressure. Let's see what the shortfalls of that are.

I've moved like an inch closer to the pump method - let's see where I am in a few days.

I do appreciate all the work that has been done before and always appreciate the help in my journey :slight_smile:

Fixed it!

Turns out I'm a bigger noob than I thought. The relay board has three ports for each relay. I was connecting to 1 and 3, but 2 is the common (ground) so I should have been connecting to 2 and 3 (or 2 and 1 for always closed).

Rewired and fixed!

Thank you for the info!

Do not forget that all the tubes and valves will have to be classified FOOD GRADE.
Will brass corrode or react someway with the ingredients you are dispensing?
Do you have a method to flush the system to clean it?

Tom... :slight_smile:


From my research, the brass won't react to the water/alcohol/coffee I'm planning to use, but i think the gaskets might react to alcohol.

That being said, I plan to use this prototype I'm building for a water dispenser for my coffee station, and move to stainless for the rest of the stuff.