Monday 9 July 2012

Solenoids for lip-syncing Twitr_janus

Been trying to work out how to get lip sync working. Thought this would need Arduino, but actually suspect analogue electronics will sort this easier.  BUT - what to use?

A keen fan of Gerry Anderson since a boy, I have looked into Supermarionation, which essentially is the brand he used for his semi-automated puppets. They had a solenoid linked to the speech input to sync-the lip movement.

This "intro to solenoids" video on YouTube is really rather good. Great Soviet Vibe. Nice, but too much effort to have to design a solenoid, and there are some serious overheating fire risks that need to be understood. This was deemed too dodgy.


BUT where to get a solenoid round the house? I thought about a doorbell solenoid first


























BUT, then realised what I wanted was sound to movement. Of course this is what a loudspeaker does. It's just a coil that moves depending on the input. Just what I needed.

I had an old speaker in the garden for BBQ music, which was no longer in use... Old speaker
The casing was mouldering and full of creatures...
Old speaker
But conveniently had solid low pass and high pass filters built in...
Old speaker

All I have to do now is work out how to drive the speaker from the laptop output, without blowing either one of them. This means understanding the spec - yikes...

Old speaker

1 comment:

  1. I have been thinking about this, too. One article indicates a special electronic filter was used, which used the analog audio signal from a tape recorder to generate electrical pulses which activate the solenoid that moves the puppet lips. They would have had to work it out using a simple scheme probably powered by vacuum tubes. 1) amplify the audio signal up to several volts amplitude. 2) use a diode to rectify the AC voltage, and charge a parallel resistor and capacitor having .1 seconds or so time constant. 3) amplify this signal comprising the electrical pulses representing the audio peaks (sylables) of the voice. 4) send this pulsating current to the solenoid via the puppet control wires. I envision 3 or 4 vacuum tubes on a custom chassis.

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