I went along to the Oxford Raspberry Jam last night at RS HQ. There were several impressive demos. But this one was definitely the best sounding of the lot. Peter Andrew has put together a solenoid sequencer (a bit like a drum machine) which is driven by a python script on a raspberry pi. He’s also written an android app to program the beat with his Nexus 7 tablet.
Solenoids are pulsed to make them strike a tin can, a jar lid, a small glass jar and a saucepan lid. The saucepan lid sounds wonderful. I loved this. Soundtrack is a bit talky I’m afraid, but that’s normal for busy events.
The breakout board is a Ciseco Slice of Pi.
I got video of some of the other demos and will publish that soon. I need to get hold of some solenoids now.
Small push-pull solenoid: Solenoids are basically electromagnets: they are made of a big coil of copper wire with an armature (a slug of metal) in the middle. When the coil is energized, the slug is pulled into the center of the coil. This makes the solenoid able to pull (from one end) or push (from the other)
This solenoid in particular is fairly small, with a 30mm long body and a ‘captive’ armature with a return spring. This means that when activated with up to 24VDC, the solenoid moves and then the voltage is removed it springs back to the original position, which is quite handy. Many lower cost solenoids are only push type or only pull type and may not have a captive armature (it’ll fall out!) or don’t have a return spring. This one even has nice mounting tabs, its a great all-purpose solenoid. (read more)
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