The Raspberry Pi Thread [4]

Just saw this in the Pi Weekly news letter, Basic Servo Use With the Raspberry Pi and GpioZero. I don't use GPIOZero but looks like some god info anyway.
https://www.raspberrypi-spy.co.uk/20...-raspberry-pi/

alphanumeric said:

Just saw this in the Pi Weekly news letter, Basic Servo Use With the Raspberry Pi and GpioZero. I don't use GPIOZero but looks like some god info anyway.
https://www.raspberrypi-spy.co.uk/20...-raspberry-pi/

Thought about using servo motor for my smart PC switch project but that would mean the Pi will always be on.

Here's a video showing basic servo contols with voice command. It starts at 0:30

Not sure what you mean by "but that would mean the Pi will always be on." ? Just so you know, the servo stays in what ever position its currently in when you remove power. It only ever moves when commanded to by the signal pin.

Thanks for that video, I will be getting myself the actual AIY board at some point. I have other things I need first though. And my budget for this type of stuff is limited.

alphanumeric said:

Not sure what you mean by "but that would mean the Pi will always be on." ? Just so you know, the servo stays in what ever position its currently in when you remove power. It only ever moves when commanded to by the signal pin.

Thanks for that video, I will be getting myself the actual AIY board at some point. I have other things I need first though. And my budget for this type of stuff is limited.

My purpose is automation. Which means, the pi that controls the servo should always be on stand by for my command.
With the smart plug, it goes to sleep and wakes up when it receives a signal from my
command.

If I have a blue LED (3.3Vf), 5V power supply with 0.5A current, what resistor to I need for the LED? 10 ohms? Is there anything less than 10 ohms?

5V - 3.3v = 1.7 V across the resistor. 50ma is 0.05 A. R=V/I 1.7/0.05 = 34 ohms. But is that 50ma what the LED wants or what your power supply can provide. 50ma seems high? I believe I used 220 ohm with my 10 mm Blue LED. The more current the brighter it gets, up to a point. Go too high and it burns out.
Have a look at this, https://www.evilmadscientist.com/201...tors-for-leds/

alphanumeric said:

5V - 3.3v = 1.7 V across the resistor. 50ma is 0.05 A. R=V/I 1.7/0.05 = 34 ohms. But is that 50ma what the LED wants or what your power supply can provide. 50ma seems high? I believe I used 220 ohm with my 10 mm Blue LED. The more current the brighter it gets, up to a point. Go too high and it burns out.
Have a look at this, https://www.evilmadscientist.com/201...tors-for-leds/

It's a phone charger power supply so it's 500mA?

A quick google search found this, https://www.sparkfun.com/products/11372 3.4V and a rated forward current of 30mA.

alphanumeric said:

A quick google search found this, https://www.sparkfun.com/products/11372 3.4V and a rated forward current of 30mA.

Ok. Thanks. I need 68ohms (using 25mA instead of 30mA). I thought it's the power supply's current that we need to account for.

badrobot said:

Ok. Thanks. I need 68ohms. I thought it's the power supply's current that we need to account for.

I have to correct what I aid above, I'm using 22 ohms not 220. They are Red, Red, Black. As near as I can tell anyway, I don't have an ohm meter handy to measure them. I'm partially color blind and they are behind a diffuser.