Just Follow Me.
This Mobile Beverage Cooler is built from several odd-fellow discarded surplus components that are reincarnated in a robust remote-controlled platform capable of delivering a chilled drink container to you with just the wave of your hand. Now don't misconstrue Follow Me as a faithful servant awaiting your beckoning call, rather this mobile cooler is a proof of concept platform that can be the basis for a bigger and grander project.
Serving as the foundation for Follow Me is a discounted plastic model tank kit. This 1/25th scale Jagdpanther kit by Academy was selected solely based on price. There is neither actual nor implied endorsement of this German tank destroyer. If you can find another large scale armored fighting vehicle kit, use it.
It's been mentioned in various books and magazines that tank kits from Academy represent one of the best bargains in mobile platform hacking. Two motors complete with gearboxes are mounted in a neat, self-contained chassis. Even if you don't intend to build a tracked beverage cooler, this motor/gearbox combination can be used in a variety of other projects.
Controlling the movements of the plastic model tank are two Passive Infrared (PIR) sensors. Rather than sound an alarm, these motion detectors are modified to trigger a relay that, in turn, activates one of the tank's electric motors. Furthermore, a PIR sensor is independently tied to each motor. Therefore, crude turns and forward movements can be controlled by signals from a combination of both sensors. All is not bliss with Follow Me, however.
There are two significant and limiting parameters that govern the operation of the PIR sensor. First, there is a 15-second delay period following each sensor trigger. Therefore, sudden changes in direction might not be picked up by Follow Me.
A second limitation can be even more stubborn to overcome. Following a trigger by the PIR sensor, the relay is held closed for approximately two seconds. This duration translates into roughly 1-2-feet of travel. If a longer time of operation is desired delay circuits can be added to the relay's output. Instructions for this type of modification are supplied with each surplus PIR sensor.
During testing of Follow Me a range of 10-15 feet was needed for obtaining optimal sensor readings. Furthermore, the sensor is more sensitive slightly off center.
The operational Follow Me Mobile Beverage Cooler is easily capable of transporting a previously chilled drink to you (provided you are patient; remember the speed is roughly 1 inch per second as you wave your hands) or you can opt for adding your own drink chilling system with a Peltier Junction. This optional add-on chiller will require a separate 6.5-12V power source (plus thermal protection and heat dissipation).
Either way, arming your next party with a battalion of Follow Me Mobile Beverage Coolers could give a new definition to getting blitzed.
Step 1: How to Build Follow Me
Difficulty: Hard; requires delicate soldering and complex circuit building
- (1) 1/25th scale Academy Jagdpanther plastic model tank kit ($43.42; Squadron.com #MH1342 ) NOTE: If this kit is sold out; try substituting this Academy Panther-G tank kit; $57.09; Hobbylinc.com #acy1341 or this Tamiya tank kit: Tiger I; $83.85; Squadron.com #TM48202. Beware there is a non-motorized version of this Jagdpanther kit #13019.
- (2) PIR sensor ($5.95; Electronic Goldmine #G4567)
- (2) Coto SPST 5VDC reed relay ($1.00; All Electronics #RLY-475)
- (2) 100mf electrolytic capacitor ($.16; DigiKey #P12919-ND)
- (2) 1N914 diode ($.30 for 10 pieces; DigiKey #1N914-TPCT-ND)
- (1) Beverage "cozy" or "snuggy," holder ($1; various discount stores)
- Scrap perforated circuit board
- Mounting hardware
- (3) "C" batteries
- (2) 9V batteries
- Cable ties
- Peltier Junction cooling device ($7.95; Electronic Goldmine #G2201)