Make a conveyor belt plus applicator
I used LEGO technic to make a conveyor belt for the food which will have some ingredient applied to it. The entry platform is adjustable so that the food enters the belt without turning.
The applicator can be positioned freely, has adjustable slope and adjustable "ingredient guides". The material of the slope should be a bit rough so that the food stays on the slope and doesn't slide off right away.
Make the LittleBits circuit
The heart of this machine is the littlebits vibration motor. It is mounted under the applicator platform.
The circuit is triggered by a littlebits light sensor. A littlebits long LED shines upwards between the two belts. When no food is around, the long LED illuminates the light sensor. When the food reaches the location of the LED and the light sensor, it blocks the light and triggers the littlebits Arduino.
The littlebits Arduino turns on the vibration motor after a certain delay. The vibration is transferred to the applicator platform, causing its ingredient to start sliding off the platform and onto the food.
the Arduino also keeps track of how long the light is blocked. It will keep the vibration motor running for the same amount of time. This way, it automatically adjusts to food of any length.
In fact, the vibration motor should stop a bit earlier (not implemented). As it is now, there's some of the ingredient falling behind the food on the belt. This can easily be changed in the program.
Since the applicator platform can be positioned freely, you have to specify the delay between the first blocking of the light and the start of the vibration. This delay is stored in EEPROM so that it is remembered when your turn the Arduino off and then back on.
The delay is in milliseconds. You can use the buttons to adjust the delay up or down in steps of 50 milliseconds. The first number bit shows the thousands and the second number bit the tens. So when the number bits show 2 and 60 respectively, this means 2600 ms. When you're done adjusting the delay, the setting will be stored automatically after 5 seconds. The number bits will briefly show 9999 as an indication that the value is stored.
Try it out!
You should now be able to apply a variety of ingredients to various types of food. I chose dry ingredients to keep our LEGO clean. I must say I cannot recommend the combination of dry rice and rusk :-)