Hi,
I'm trying to use an 5v arduino based microcontroller design from a 24 VAC power supply. I want to convert the 24VAC to DC and then step down the voltage to 5v to power the microcontroller.
My design is the following based on the LM2569 voltage regulator and borrows ideas from various sources on the internet. I am not sure about the capacitors, I'm using a 220uf after the diode bridge should it be bigger? smaller?
Any other ideas to improve the design? Thanks in advance.
LM2569? LM2596 you mean?
What frequency 24Vac? You may need an extra smoothing capacitor if its mains frequency.
But to calculate that you need to know the max current draw. Given the high input voltage
and low current before the step-down the existing 220uF may be enough. A conduction
angle resistor might be useful too, but its not clear without numbers on that current consumption.
What's your source for that 24V AC? is it from an synchronous motor being used as a generator?
Sorry LM2596
The power supply I have is 24VAC 50Hz 2A, like this one AC2410 24VAC 1AMP AC POWER SUPPLY |
The power consumition will be arround 80mA for the arduino UNO + LCD , very low.
24volt AC will be a minimum of ~33volt DC on the 220uF buffer cap.
Likely close to 40volt with a light load.
Very inefficient/dangerous/bad way to power a 5volt Arduino.
Drop the whole idea, and use a 5volt cellphone charger.
Leo..
Wawa:
24volt AC will be a minimum of ~33volt DC on the 220uF buffer cap.
Likely close to 40volt with a light load.
Very inefficient/dangerous/bad way to power a 5volt Arduino.Drop the whole idea, and use a 5volt cellphone charger.
Leo..
It's not an option, I only have 24VAC available. I have to create the most efficient power supply possible. based on 24VAC to 5VDC Conversion « RAYSHOBBY.NET
Well with only 80mA load its probably fine - but that circuit is not isolated from the 24Vac, which
could be an issue.
Your diagram has completely spurious supply symbols marked +24V and -24V which are wrong.
MarkT:
Well with only 80mA load its probably fine - but that circuit is not isolated from the 24Vac, which
could be an issue.
Why are not isolated? They not share any net with the DC part of the circuit.
MarkT:
Your diagram has completely spurious supply symbols marked +24V and -24V which are wrong.
In another part of my schematic I'm using both nets as a load to a relay, I didn't know how to name both nets.
MarkT:
Well with only 80mA load its probably fine - but that circuit is not isolated from the 24Vac, which
could be an issue.
How should I isolate both circuits? They are not sharing GND
How should I isolate both circuits? They are not sharing GND
Yes they are. D2 and D4 are the path. There is no way to isolate the 24VAC from GND with what you are doing. That may not be an issue but we have no way of knowing.
You need show the other part of your schematic so we can see what the 24VAC is connected to as well as any sensors or any other reference voltage/connection that may interfere.
