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Chat => Entertainment & Technology => Topic started by: M3ta7h3ad on September 02, 2014, 06:11:52 AM

Title: Solenoids and Raspberry Pi's
Post by: M3ta7h3ad on September 02, 2014, 06:11:52 AM
So I have an idea that requires me to trigger a couple of physical button presses using a raspberry pi.

In particular I need to press 2 buttons on a Dictaphone to start and stop recording so I don't want anything too beefy 1KG of force is likely to punch holes in my Dictaphone and the reason I need to use solenoids is because I don't want to tear apart what is a nice digital voice recorder for a pet project I've in mind.

My questions are:

1. How would you trigger one?
- thinking of using a piborg (MOSFET expansion board) or wiring up a relay but a relay to trigger a relay (solenoid) sounds stupid in my head.

2. Could you recommend some "gentle" solenoids suitable for a raspberry pi project ideally running on less than 12v so I can make use of old power adapters for a power supply?

And just to preempt the "just record audio using the pi" crowd. The pi is likely to already be doing a lot (old model B with 256mb ram) and my voice recorder is a decent quality that I think it'd beat any cheap USB mic I bought for the pi.

Cheers!
Title: Re: Solenoids and Raspberry Pi's
Post by: bytejunkie on September 02, 2014, 12:21:25 PM
eccentric cam wheel would be gentler than a solonoid. put it on the end of the solenoid and you're laughing.

i need an auger for my r pi project. struggling to find on in plastic.
Title: Re: Solenoids and Raspberry Pi's
Post by: M3ta7h3ad on September 02, 2014, 18:13:55 PM
*goes off to google eccentric cam wheels and plastic augers :) *
Title: Re: Solenoids and Raspberry Pi's
Post by: bytejunkie on September 03, 2014, 07:33:49 AM
plastic auger is for my automated dog feeder project. its basically a corkscrew that i can spin, by attaching a motor. if it does 100g per second then Rufus needs 4.4 seconds of food a day.

eccentric cam wheel. so basically, put a wheel right next to the button. put the pivot point, ie the axle through the wheel, just off centre, by half the amount it takes to depress the button. you no either use a solenoid with a throw just over the lenth you press the button and power it for a complete revlution of the wheel to simulate a button press. or use a lego motor and cog to spin the wheel a certain amount of time.

make sense?
Title: Re: Solenoids and Raspberry Pi's
Post by: M3ta7h3ad on September 03, 2014, 07:59:26 AM
Ah stepper motor might be a better solution then rather than solenoid. Thanks.