Spinster

Spinster v1.0

This is Spinster the Headbot. He's my first bot using a Power Smart Head circuit that uses the 74HCT240 chip. This chip is different from the usual one used for headbots in that the switching thresholds are 1/3 and 2/3 of the supply voltage. Normally I use a chip that has a switching threshold of 1/2 of the supply voltage. The mechanical parts are from an old CD-ROM drive from a computer.

Spinster (side view)

I used a CD for the base. Glued to the CD is an old knob from a stereo used as a spacer. I then glued the knob to one of the gears in the drive assembly. I made Spinster battery powered so he would be very active. He can quickly spin around to follow a light source and he has 2 green LED's which blink when he's locked on. These LED's are required to adapt the circuit to work with the 74HCT240 chip. Notice all the extra space on Spinster's back? I am hoping to eventually add another head circuit and motor assembly there so that Spinster can look up and down as well as left to right.

Spinster (underside)

Here you can Spinster's drive system. The black spot beside the big gear is where he sits on his base assembly. I opted to leave the base loose so it wound be easier to transport and store him. On the CD is his name and build date. This is something I recently started doing to help keep track of the many robots threatening to invade our home.

Spinster's Brain

Here you can see a little closer photo of Spinster's Brain. The small block on top of the motor is an H-Bridge. The H-Bridge is used because the outputs of the brain chip aren't powerful enough to handle the power the motor requires. Those in the know may notice there are no variable resistors in the circuit. I adjusted them and got the performance I wanted and then replaced them with fixed value pieces.

The Power Smart Head v1.1 Schematic

This is the original schematic designed by none other than Wilf Rigter himself. I used this to build the circuit initially.

Spinster's Actual Schematic

And here's the actual completed schematic used on Spinster. I will add the Freeform Drawing at a later date for those interested.

Spinster was fun to build! I'll be building many more bots using the PSH v1.1 circuit because I have a ready supply of 74HCT240 chips. The total cost for materials to build this bot: $2.00. The battery holders cost $1.00 and the 74HCT240 chip was $1.00. Everything else I salvaged from a junk computer! Cool huh?!