The lemon vendor dispenses single slices of lemon. The design is based on the mechanism seen in many vending machines, e.g. like the one at Nottinghack. The mechanism is made from a length of mini guttering and a geared motor found in the motors draw at the space. A cam and micro-switch are used to control rotation of the vending coil. One side of a dual L298N H-bridge module along with a ATtiny85 controls the motor. The /RESET signal of the ATtiny85 is used to start the vend cycle.
- The lemon slices need to be quite thin (2-3 mm)
- The lemon slices need to be larger than the coil diameter, otherwise the coil "screws" over them, rather than pushing them along
- After use the mechanism should be run under a tap to clean it, however try to avoid getting the motor wet.
Mounting & hardware
Two mini gutter mounts are used for mounting, however these must be fitted near to the motor end otherwise they can interfere with the movement of the lemon slices.
To vend one slice of lemon the /RESET line of the ATtiny85 needs to be taken low. One vend cycle takes TBC seconds to complete
- /RESET ("start" signal)
+12V, TBC mA
None really! However, there is a red LED on the L298N module which illuminates when power is available.