pi pwm circuit
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- cmitcham
- Posts: 2
- Joined: Tue Nov 29, 2022 12:18 pm
pi pwm circuit
will the circuit in mike's picture above switch fast enough to use on a pi pwm pin? i need to dim a cheap string of leds. and (if so) i'm guessing with a led load, i wont need the protection diode?
thanks!
- dastels
- Posts: 15667
- Joined: Tue Oct 20, 2015 3:22 pm
Re: pi pwm circuit
So... not that circuit?
Relays are way too slow to PWM. What LEDs are you using?
Have a look at https://learn.adafruit.com/transistors-101/example-uses. In that example I PWM a 12v LED strip to control brightness which sounds like what you want to do.
Dave
Relays are way too slow to PWM. What LEDs are you using?
Have a look at https://learn.adafruit.com/transistors-101/example-uses. In that example I PWM a 12v LED strip to control brightness which sounds like what you want to do.
Dave
- adafruit_support_mike
- Posts: 67454
- Joined: Thu Feb 11, 2010 2:51 pm
Re: pi pwm circuit
Easily.
BJTs usually start to have trouble around 300MHz (meaning you have a specific need for the ones that operate into the gigahertz range), and power mosfets can handle 1MHz without too much trouble.
That said, Dave's right: most of a relay driver circuit is unnecessary for what you want to do. A simple power mosfet switch will be fine.
Please be positive and constructive with your questions and comments.