# Hacking



## jaege (Aug 23, 2009)

I have the Gemmy talking skull with the moving eyes ( non-lighting) Has anyone ever hacked this actual skull? I see some other hacks here, but I don't think anything that specifically speaks of this one. Since I am somewhat a novice in the fine electronics area, I would have a tough time extrapolating from one of the others to this one and was hoping for some thing more specific. 

By hack I mean I would like to be able to add my own sound routine that the skull responds to, rather than the goofy sounds and laughter that it came with.


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## hedg12 (Jul 6, 2008)

I have one that I converted to use servos with. If you want to use the existing motors to drive the jaw and eyes, you'll pretty much have to do away with the original circuit board and use something like a toy motor circuit to sync the jaw to audio. The eyes would be a different story - the one I have was broken when I bought it so I never experimented with the mech for the eyes - not sure how you'd go about controlling them. If there's a limit switch on the eye mechanism, you could incorporate a fairly simple Picaxe controller to randomly move them.
There are quite a few posts here about hacking the Gemmy stuff - it's really not too hard once you dive into it.


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## hedg12 (Jul 6, 2008)

Just a thought too - if you don't want to use the toy motor circuit, you could use the ST300 from Cowlacious. It's designed to drive a servo, but it also has an output that would drive the motor. It's limited to 500 milliamps so I'm not sure if it could drive it directly, but it would be easy enough to add a transistor between the motor and ST300 that would handle the load.


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## jaege (Aug 23, 2009)

I think I will try that board from cowlacious. Thanks. Are you saying that the 500 ma is too little power or too much?


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## hedg12 (Jul 6, 2008)

jaege said:


> I think I will try that board from cowlacious. Thanks. Are you saying that the 500 ma is too little power or too much?


Too little - you can't have too much. I doubt the motor would draw that much, but I'm not sure. Better safe than sorry.


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## RandalB (Jun 8, 2009)

I used a 5v wall wart and a color organ to drive the jaw motor directly, The eyes are a different story, my skull had LED's that I wired up directly to the same wall wart so they flashed in sync to the jaw movements. If you are talking about the skull that has the moving eyes, you have to supply their motor with alternating +5 and -5 to get them to move back and forth. You'd need some kind of driver for that, maybe the servo driver mentioned above...

RandalB


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## jaege (Aug 23, 2009)

Thanks. I now have some basic knowledge to work with.


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## fritz42_male (May 5, 2009)

RandalB said:


> I used a 5v wall wart and a color organ to drive the jaw motor directly, The eyes are a different story, my skull had LED's that I wired up directly to the same wall wart so they flashed in sync to the jaw movements. If you are talking about the skull that has the moving eyes, you have to supply their motor with alternating +5 and -5 to get them to move back and forth. You'd need some kind of driver for that, maybe the servo driver mentioned above...
> 
> RandalB


Just out of curiosity which Colour Organ kit did you use?

The Toy Motor Circuit is from Jim Kadel of Hauntmaster Products and he used to sell his own commercial version - I persuaded him to sell me a 2 output one for a pair of Dracula heads I'm playing with. His commercial one is a bit more fancy with line level input and a 555 timer in the circuit to extend the pulse time for opening the mouth.


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## RandalB (Jun 8, 2009)

It was an $6.50 special from Electronic goldmine, I believe...


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## Scottzilla (Jun 13, 2007)

jaege said:


> Are you saying that the 500 ma is too little power or too much?





hedg12 said:


> Too little - you can't have too much. I doubt the motor would draw that much, but I'm not sure. Better safe than sorry.


The motors in the Gemmy skulls I have draw about 460ma fully loaded; just under the limit of the Cowlacious board outputs. You should be fine.

Here's a tutorial showing how to mod a talking skull. It's the skull without the moving eyes (they're pretty close except yours has an extra motor / gear box for the eyes), and it's a different board than you're using, but it's got lots of pictures and might help give you an idea of what you're up against.


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## jaege (Aug 23, 2009)

That is useful. Thanks.


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