# Custom voice for Gemmy Skulls



## heresjohnny (Feb 15, 2006)

A while back Dr Morbius started a great thread about driving a skull lantern with custom audio instead of the phrases that came with it from the store. He used what everyone calls the toy motor circuit, and it worked great for him. I tried the toy motor circuit and there were a couple of things I did not like. One, you needed a rather strong amplified output hooked up to the circuit and 2) you need a wall wart of computer power supply to power it. I really wanted something that would let me provide the audio, use a line or head phone level output from an mp3 player, and work with batterys.

What I came up with was a modification to the Scary Terry Audio Driver circuit found here: Scary Terry Circuit. I added a Darlington pair (TIP120)on the output to drive the jaw. 









Here is a video of the circuit in action:






Some things about this circuit. It uses a headphone level input from an mp3 player, is adjustable, can drive the jaw and the LED eyes, and it can be connected in parallel with a powered speaker so you can control the volume of the audio without affecting the jaw action.

There were a couple of more things I wanted to add to the circuit. One is a latch that will hold the LED eyes on while talking, instead of flashing. The other is to drive a small motor briefly when the skull starts talking after a brief pause, this would be used to slowly turn the head back and forth. This would give you a talking head to your custom audio that would move back and forth a little while talking. Don't know if I will get the modifications done before Halloween or not.


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## samseide (Jun 1, 2010)

Very good hack! How much did you end up spending for all the parts list on this? I built my talking skeleton head using a arduino and a servo but an arduino is $35 then you spend $15 on a servo and it clocks in at $50 before you even add in eyes or other head movement. Was wondering if this ends up being a cheaper option.


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## Otaku (Dec 3, 2004)

Cool, John! I've seen some talking skulls at Target this year that have a set of canned phrases, but knowing what a pain they've been to hack I've always passed on buying them. Looks like this circuit fixed that little issue! Nice work - thanks for sharing this.
Just thought of something - does the sound source ground (MP3 player) need to be on the same ground plane as the rest of the circuit?


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## heresjohnny (Feb 15, 2006)

samseide, I don't have an exact price list, but its well under $10. The most expensive thing is the 5k pot.

Otaku, if you mean the input (where the mp3 player is plugged in via the jack), yes it shares common ground with the rest of the circuit.


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## samseide (Jun 1, 2010)

wow! under $10 is a great price point on these. Gonna have to look into building my skeleton army for next halloween.


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## Otaku (Dec 3, 2004)

Hey John, one more question. The line between D1 and R8, is that a connection or a crossover?


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## heresjohnny (Feb 15, 2006)

Thats a connection.



Otaku said:


> Hey John, one more question. The line between D1 and R8, is that a connection or a crossover?


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## Otaku (Dec 3, 2004)

Cool, thanks.


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