Sentinel

I took what was left of Fleet Beacon and added it to a Miller Solar Engine to create this bot. It is essentially two separate circuits on one frame. The first is a classic Miller Solar engine that charges up in the sun and manages to spin the entire robot for a few rotations. I used two 45x25mm solar panels in series for the spinner circuit, which equates to 10v at 30mA. Normally this would be total overkill for the circuit, as the voltage trigger fires at around 4.9v, but I wanted the robot to spin even in less than ideal conditions.

The second circuit is the leftover parts of Fleet Beacon, repaired and attached to the underside of the side solar panels. It is a dark activated pummer that blinks red LEDs for a few hours when the light is low enough.

I used some 1/8" channeled square brass tubing that I picked up from Ace Hardware for the frame of this robot, and I couldn't be happier with how it turned out. I love the look, and the strength is great too. For making angled turns, I clipped out a section of the tubing, bent it to the appropriate angle, then re soldered the edges together for extra strength. It also allowed me to tuck the winged solar panel wires into it to hide them quite effectively.

Overall I am very happy with this bot. It spins during the day, and blinks at night. Leaving for work in the morning he happily spins away, and coming home in the evening he will blink away until bed time.

Carbot 2

The creatively titled Carbot 2 is born! This bot uses the same Miller Solar Engine circuit as the previous Carbot, but some changes were made. I wired six 1V 30mA solar panels in series to produce 6V @ 30mA. A 2.2uF timing capacitor was used to give it adaquate spinning time, as the hefty spinner required it! It was constructed from brass rod and large plastic beads. The sun reflects off them quite nicely.

Originally I was planning on using three 4700uF storage capacitors in series to achieve 14,100 uF, but I only had two! I was worried that two would not be enough capacitance to spin this bulky spinner, so I opted to use what I had lying around: three .3F 2.7V supercapacitors in series, which equals .1F @ 8.1V. In this configuration, the bot takes about 30 seconds of charging in full sunlight before it begins to spin every few seconds.

The solar panels are held together with hot glue and jumbo paperclips, which is connected to the main chassis and motor by E6000 and tension. I would have preferred to build this bot with more toughness, but I ran out of time, as it was a Christmas gift. Also, as a stationary spinner, it will not see too much action!

As 131 triggers are hard to come by these days, i instead used the MCP112 equivalent drop-in IC (MCP112-450E) which triggers at 4.38V. The higher trigger voltage points gives the motor enough juice to get spinning.

Tornadobot

This little guy hangs from a chain suspended from the rear view mirror in my car. Utilizing two 24x22mm solar cells in series, Tornadobot builds charge then throws all its power into the propellor which is connected to the chain on either side. The result is quite a jolt, but eventually settles into a controlled spin. I have recently re-balanced it so it doesn't bounce around as much. It has a 0.047F supercap to provide the bulk of the power, with a supplemental 4700uF cap in parallel. I was initially afraid the internal resistance of the super capacitor (I think ~200 Ohms) would be too high for this motor, so I added the extra capacitor to aid in the initial burst, but also to aid in balancing this bot.

The propellor is attached to the motor shaft with Krazy glue (cyanoacrylate) and heat shrink. I actually use Krazy glue quite often in my bots. It gives a very strong bond regardless of which materials I am bonding.

UPDATE:
So after a few years the motor started acting funky. I actually got a bit of hot glue inside of it when I first was building this bot, and I think it finally took its toll. So I updated this bot with a 600 RPM N20 gear motor. It's activation is much more calm! This will improve the bot's lifespan by putting less strain on the motor and the rest of the parts by making it less likely to fly off the chain and break its self.

Fleet Beacon

Fleet Beacon was my first attempt to utilize the 74**240 Bicore chip after my last failure with Syko. He is a pummer that builds charge during the day, and when the light level gets dark enough, switches on an LED blinking circuit. I used a 1.5F Powerstor supercap and a 74HCT240 chip to do the thinking.

With a 1.5F cap, this bot blinks away for about an hour after sunset before draining it's power. The efficiency on this bot could be improved by implementing Wilf Rigter's PowerSaver Flasher circuit, using a storage capacitor that has a higher voltage rating. Currently this one is rated for 2.7V. From what I know about the HCT flavor of bicore chips, they seem to work better when normalized to 5V supply voltage. I could be losing power there. I also did not have any schottky diodes on hand, so I had to use a standard silicon 1N914 version. Other builders seem to get much more efficiency out of their nocturnal pummers. I must have a power leak somewhere!

I do not like how I designed the LED antenna. It doesn't match the style of the base of the robot. I may re-design it later when I get some inspiration.

I used this Makezine PDF as a guide, but altered it a bit by removing the 'pumming' feature and opted for a simple alternating blinking set of LEDs

UPDATE:
In case you were wondering what a blown out capacitor looks like, here it is.

This is what happens when you try to store more charge at a higher voltage than the capacitor is rated for. The Solar Cell on Fleet Beacon can put out 4.7V, while this capacitor is only rated for 2.7V! Since the capacitor remains charged while it is sunny out, this voltage is held on the cap all day. After less than a year the cap called it quits and blew out. I have replaced it with two 10F 2.7V capacitors in series equaling 5F rated at 5.4V, which will do just fine in this circuit. Fleet Beacon will be repurposed soon in another project!

Carbot

Carbot (creative name, I know) was designed to be a simple miller engine that sticks to the inside of your car's windshield. With its outward facing solar panel, it will build up charge on its three 5600uF capacitors and release that energy in one big burst on the bulky DC motor in the center. The load on its shaft is a bit heavy (the LEDs on the propeller are non-functional), so the solar engine needs a decent amount of charge to build any momentum. The inspiration for this bot was taken from the now defunct Jim's BEAM Page. Jim made an impact with his special attention to the Aesthetics part of BEAM. What remains of his designs can be viewed in very poor resolution at beam-online.com

HipHopper

My first experience with the 1381 voltage detector. This circuit used in HipHopper is the 1381-based solar engine. He is powered by a 24 x 33mm Panasonic cell connected to a 1.5F PowerStor super capacitor. His body is built on a paperclip chassis, and when firing, this robot will bounce all over the robot farm. Some robot builders call this style a Vibrobot.

1381's are increasingly hard to find nowadays as they have been discontinued. Luckily the folks at Solarbotics tracked down a direct drop-in replacement for the 1381 named the MCP112.