Electrical question

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jrraines

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I was inspired by the cuckoo clock posted on the blog. I have a very old cd drive tray mechanism, which I stripped down to just the part that moves the tray in an out. 5v applied in one direction will move it out and in when the voltage is reversed. I don't actually know anything about the motor's specs. It will move it with a rubber duck on it. I have ordered an elvis rubber duck...

I'm hoping to use a teensy 3.6 and a prop shield LC. The audio portion could play 'rock around the clock' (I know, Bill Haley not Elvis--Bill didn't get a duck). Probably something that would be funny once, I know.

Now for the part that's beyond me: can I use the 5v buffered part of the prop shield LC that is intended to drive LEDs to drive 5v in one direction to push it out and the other direction to pull it in? There is a circuit for the 'clock' and one for the 'data'--can I drive one to ground and the other to 5v to 'eject' Elvis and then the other to ground and the one to 5v to pull it in?
 
jrraines said:
I was inspired by the cuckoo clock posted on the blog. I have a very old cd drive tray mechanism, which I stripped down to just the part that moves the tray in an out. 5v applied in one direction will move it out and in when the voltage is reversed. I don't actually know anything about the motor's specs. It will move it with a rubber duck on it. I have ordered an elvis rubber duck...

I'm hoping to use a teensy 3.6 and a prop shield LC. The audio portion could play 'rock around the clock' (I know, Bill Haley not Elvis--Bill didn't get a duck). Probably something that would be funny once, I know.

Now for the part that's beyond me: can I use the 5v buffered part of the prop shield LC that is intended to drive LEDs to drive 5v in one direction to push it out and the other direction to pull it in? There is a circuit for the 'clock' and one for the 'data'--can I drive one to ground and the other to 5v to 'eject' Elvis and then the other to ground and the one to 5v to pull it in?
Click to expand...

The prop shield has two conversions from 3.3v output to 5v. If you set pin 7 HIGH, then pins 11 and 13 are converted from 3.3v to 5v, and the pins are at the end of the prop shield. The prop shield has two conversions so that you could use it for either APA102 (dotstar) or WS2812B (neopixel) LEDs. Note, since pins 13/11 are SPI pins, if you also want to use a SPI display, you will need to switch the pins manually between normal data mode and SPI mode.

Since the 3.5 and 3.6 are longer than the Teensy 3.6, you would need to run a wire from the first DAC (A21) on the 3.5 to the place on the prop shield if you wanted to use the built-in amplifier on the prop shield (you have to set pin 5 HIGH to enable the amplifier).
 
Have you measured the current draw of the tray motor? I'd start with that. The AHCT logic can source or sink 8 mA according to spec. It can actually do a bit more than that, especially if it's low duty cycle use but if your motor is much above 20mA, I'd look into using an H-Bridge.
 
You can also create an H-bridge with opto-couplers. The ILQ74 has four sections with a max current of 60mA. With two Teensy output pins, you can get three states, in, out, and dormant. The circuitry and code are quite simple.

The chip is available from Newark. I've used the ILD74 dual channel to make an RC signal switcher equivalent to a 3PDT relay. This is used in a drone/plane as the crossover controller.
 
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