Mini Tail Servo Controller

This product has gone obsolete see this version for a replacement: Mini Tail and Ear Servo Controller Version 2

I have had many requests for tail servo control boards.  Unfortunately the original the microcontroller that was originally used in the tail controller has gone obsolete, so I can't sell and/or make those any more.

Thus, I have designed a stand alone user programmable tail servo control board.

The entire board is less then 1 square inch and should fit perfectly into a tail.


The mini tail servo controller can be 100% programmed from the buttons, with out the use of a PC or any other programs.

The key features for the new servo control board based on the Atmel ATmega16:

16K flash (the old micro had only 2K of flash)

16 Mhz (the old micro ran at 10 Mhz)

2 channel 16 bit servo resolution (the old micro was 10 bit)

5 control buttons (the old one had 3)

Because the old board only had 2K of flash, and I used it all up, I could not get all the features I wanted into it.

This new tail controller includes everything from the old tail controller plus the following:

High resolution servo loop, capable of generating a servo pulse width from 0.05ms to 3ms in 47456 steps. 

New Button code, with debouce, and button hold detect. When programming, instead of having to press a button a bunch of times to move the servo to where you want it, you can just hold down the button and it will do it for you.

All values are bounded and checked to prevent counter roll over and possible damage to a servo.

Improved EEPROM read/write and restoration of system defaults.

Random function generator, which uses a linear congruential pseudo random number generator.  It is seeded by the main loop free running counter, the last time each button has been pressed, the voltage of the battery, the voltage of the micro core, and the summation of the 6 other ADC channels, which are floating and pick up all kinds of nice electrical noise.

The mini tail servo controller is designed to run off a 4.8 or 6 volt battery.

Either 4 cell alkaline, or 4 or 5 cell NiCd, or 4 or 5 cell NiMH.

The controller will shutdown when the battery voltage is around 2.7 volts.

The tail is controlled by 5 buttons:

B1 toggles between normal, slow wag and fast wag.

note: the mini tail servo controller comes programmed with default settings for a wolf, dog or other canine, if you want it to be more feline, then you need to slow down the wag speeds, this will make the tail swish more like a feline's tail (see B5).

B2 tucks the tail under

B3 raises the tail 

B4 enables, disables random mode. When enabled, the tail will randomly chose one of the following motions after a random amount of time:

Slow tail flick, Fast tail flick, Slow wag, Fast wag (either waging modes will wag for a random amount of cycles), pressing any button will disable random mode.

B5 enters program mode, see how to program a mini tail servo controller

The mini tail servo controller, connector pin out is as follows:

The POWER connector (the square pad is pin 1):

(Pin 1 is not connected), (Pin 2 is +6 volts), (Pin 3 is GND)

The BUTTONS connector (the square pad is pin 1):

(Pin 1 is B1), (Pin 2 is B2), (Pin 3 is B3), (Pin 4 is B4), (Pin 5 is B5), (Pin 6 is GND)

If you make your own button board, the momentary switches should short the buttons (pins 1-5) to GND (pin 6)

The SERVOS connector (the square pad is pin 1):

(Pin 1 is Signal), (Pin 2 is +6 volts), (Pin 3 is GND)

You can use any servo so long as the pin out matches the above connector.

Most of servos are this way, only some of the older ones have different pin outs, it is always best to check the documentation that comes with your servos.

Both analog or digital servos will work, however I would only recommend servos with all metal gears in animatronic applications.

Note: If you are using digital servos, they will not travel a full 180 degrees. You need to reprogram then using a digital servo programmer to enable the full range.

For step by step hook up instructions, see how to install a mini tail servo controller.

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