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founder: tutchek
depends on:
interested: harvie
software license:
hardware license:

~~META: status = suspended &relation firstimage = :project:bartender.jpg ~~

The aim of this project is to construct automatic bartender. The bartender should be able to:

  • Serve drinks from bottles inside the device in relatively accurate quantities
  • Mix (possibly even stir) the drinks in the glass
  • Provide an easy-to-use interface for creating new drinks
  • Account money. This can be done either by RFID chips (for hackerspace members) or using a coin acceptor (for people from outside the hackerspace)

Some optional features include:

  • Serving sugar and other solid ingredients to allow an even greater variety of beverages
  • Tapping beer
  • Mixing carbon-dioxide into the beverage on-the-fly
  • Serving hot or chilled beverages, or even making ice
  • Post-mixing Coke and other soft drinks
  • Recipes on punched cards :-) P4IeZLDJ1dA



First working version!


First prototype



BrmTender Shield Beta

Arduino-readable Recipes


  • New recipes and components are welcome!
  • I don't know how to dispose sugar, so we can mix it with little watter and dispose it as liquid
  • Price of each drink will be automatically generated
Coctail name\Components vodka rum havana coke juice matoni tequila sugar
ID (number) 01234567
ID (duino pin) 12111098765
Vodka+Juice 1 7
Bohemia libre 1 7
Cuba libre 17
Mojito 3 5 1
Tequila Sunrise 5 3


FIXME = donate to implement your favorite beverage :-)

Part Price Donor Status
BRMduino + FTDI board350+300sargonbuyed, paid, completed
BRMduino shield80harviebuyed, paid, completed
Small fridge to be drilled~1200? (aukro)FIXME
Pump + hose (vodka)299+13FIXME
Pump + hose (rum)299+13FIXME
Pump + hose (havana)299+13FIXME
Pump + hose (coke)299+13FIXME
Pump + hose (juice)299+13harviebuyed, paid
Pump + hose (matoni)299+13FIXME
Pump + hose (tequila)299+13FIXME


Brmtender shield

There will be pot that will allow us to tune PWM duty cycle that will be globally aplied to all outputs of ULN IC.


There are several ways that we can do this. All of them share the same principle - several drink containers that are connected to the outlet. Below, we can share ideas regarding various technologies and designs.

3D printable peristaltic pumps

I guess that this is quite breaktrough for our project:


Pressurized system vs. gravity or low-pressure dosage

The whole system could be under pressure, which forces the fluids out of their containers into the glasses. Another approach is to let the fluids flow out freely under the influence of gravity of by carefully injecting short bursts of air into the containers, letting the exact amount of fluid out of the container.

Advantages of pressurized system

  • We don't have to measure the amount of fluid, we just calibrate the system and open the output valve for the correct amount of time
  • The containers don't have to be stored above the outlet and they don't have to be upside-down
  • Easy addition of carbon dioxide

Advantages of gravity-driven system

  • Easier construction
  • No leaks of fluids or pressure

Cheap food-grade solenoid valves from China

The problem with solenoid valves is that they are very expensive (especially the ones that are approved to be used in food processing industry). However, we found some Chinese supplier of food-grade (or so they say) valves that can be used in pressurized systems with pressures up to 8 psi. They claimed the price of one unit between 1 and 5 dollars. The lowest quantity to order is 100 pieces, however. We already contacted the company so let's see what they'll come up with :-)


Cooling can be done either using a compressor from an old fridge or by Peltier cells. The disadvantage of Peltier cooling is that it is very ineffective, but it is quiet. Also, if the system would be pressurized, serving the drinks would probably mean that they would automatically cool slightly.

Another possible aproach is to simply put all of the containers into the fridge and drill little holes for hoses to it. It can be even some cheap 12V fridge for motorists.


We think that everything could be driven by a single (Ar/BRM)duino board. We would then create a simple protocol that would enable us to control the whole device using a PC. The device would know the ingredients that are present in it and also the prices of them. It would also contain a database of drinks. It would be able to calculate the price of each drink and also whether or not there are enough ingredients for the given drink.


The whole system could be connected to the accounting system for BRMbar and it could also have a separate coin acceptor, so that visitors without a profile in the accounting system would also be able to order drinks.

Coin acceptors

Cestmir already contacted some guys from Prague who are selling some coin acceptors. They are manufacturing some video terminals and have recently decommissioned several devices and have around 500 coin acceptors at their disposal. The price would be around 700 CZK per unit. The acceptors are without coin holders, so we would have to create them. The advantage of creating our own coin tubes is that we can easily make the machine return change. The guy has promised to send me some technical info on the acceptors (datasheets etc.)


The cabinet design will have to take into consideration all the previous design decisions. Basically, I am imagining a box the size of a small table with an outlet coming from the to of it. Maybe everything could just fit into the fridge :-D


project/bartender/start.txt · Last modified: 2016/11/28 01:52 by ruza