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R/C Sentinel Tank to Robot Conversion

---[ this project is currently inactive] ---


Original Tank
[tank]
This project involves robotic conversion of a Radio Shack R/C Sentinel Tank, model 60-4257, which was sold in outlet stores in the year 2000 timeframe.

The original tank is about 12" long x 6" wide x 4.5" high [305 x 152 x 115 mm], with a 6" [155 mm] long barrel extending well past the front end. It has a 2-channel differential drive, rotating turret, simulated motor noise, and a bright LED in the end of the barrel. The tank is geared down with a lot of torque, and can climb pitches to about 40 degrees. The slow speed makes it more amenable to robotic conversion than a lot of the fast R/C cars which are built for speed rather than sensitivity.

[first 4 pictures courtesy of Dennis L. Clark]


[innards] This figure shows the innards of the Sentinel Tank. In the center is a motor and gear mechanism used to rotate the turret. In the rear are the two strong drivemotor - geartrains, and on-off switches. In the front is the original controller board, components facing down. In the upper section are the motor noise speaker, LED power leads, and antenna wire. The original uses a 6v rechargeable battery pack accessible from underneath.

The track drive can also be seen here. 6 wheels provide even traction along the bottom of the tread, and raised wheels front and back facilitate climbing. Several tread guides can also be seen along the top of the tread and just in front of the rearmost drive wheel. The rear guide apparently keeps the tread from bunching up and jamming between the drive wheel and the idler wheel just in front.

All in all, a nice design, with lots of internal room to work with for a robotic conversion.


[controller] This figure shows the area around the original controller board. On the pcb right are 8 large and 4 small transistors making up 2 h-bridges for motor drive. On the pcb left is a discrete component R/C receiver, and beneath the h-bridges is a small potted chip, which apparently controls logic operations.

The space in front of the turret motor is a large 5" x 3" [130 x 80 mm], and has plenty of room for a new controller and auxiliary devices. The space under the controller mounts is the battery hold. The speaker is a nice 2.25" diameter [57 mm] permanent magnet 8 ohm, 0.5W device. 1/2 watt! Not your typical midtown piezo.


[turret] This figure shows the detail of the turret. A nylon ring forms the rotator surface, the barrel swings up and down along a guide as the turret rotates, and the RF loop antenna sits inside. The flange which holds the turret onto the tank body and connects to the turret drive motor is missing from the picture.

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