hi, im in the process of building an isolated power supply for my arduino project. right now im using an isolation transformer 120-24v ac. the output side of the transformer goes straight into a bridge rectifier and then into a dc buck converter. everything is working but i notice some of my sensors fluctuate a little bit and im sure this is probably the voltage fluctuating. whats can i do to filter this output power to make sure it remains at a stable voltage with minimal noise? the buck converter is set to 5v (its adjustable).
Use a linear regulator.
Start with how this is packaged physically and what electrical reality that creates..
Suggest you take a look at this:
Arduino-Project-Planning-Electrical
Apply that to both your power supply AND your project..
Adding both large and small value capacitors (Say 100uf and 0.1 uf) across the output is one start.
But Where IS Ground??
MarkT:
Use a linear regulator.
that's what i had in mind but i was not sure. my meter is not fast enough to read the voltage accurately. now i need to find a metal project box and some kind of shielded tape for some of my wires? thanks
terryking228:
Start with how this is packaged physically and what electrical reality that creates..Suggest you take a look at this:
Arduino-Project-Planning-Electrical
Apply that to both your power supply AND your project..
Adding both large and small value capacitors (Say 100uf and 0.1 uf) across the output is one start.
But Where IS Ground??
i had to isolate my mains ground from my sensors because my sensors are in the water and i was having bad ground loops issues because of the other electronics in the water that are plggued into the mains ac. now my ground loops issues seem to be resolved but there is a lot of EMI around the transformer. the transformer is 50ft away from the arduino but i know there is some noise coming up the wire. too bad i cant find a small metal project box i can make a cage from
Blank, double sided fr4 pc board makes a nice shielded box - if you have a real soldering iron, not one of those $5 Chinese things.
avr_fred:
Blank, double sided fr4 pc board makes a nice shielded box - if you have a real soldering iron, not one of those $5 Chinese things.
in a few days im going to switch to this transformer and add a RC filter before the linear regulators. i will however have to connect another 120v power supply to the output of the first transformer so that will eliminate the buck converter. also do you think i could get away with using 2 blank pcb one size match the cover and one on the bottom be enough?
notsolowki:
in a few days im going to switch to this transformer and add a RC filter before the linear regulators.
Why add an RC filter before the regulators? The regulator can do 60 to 80dB of noise attentuation, RC is
nothing compared to that.
notsolowki:
is a lot of EMI around the transformer. the transformer is 50ft away from the arduino
Noise (power line hum 60 Hz ? )is coming not from transformer wirelessly, is travel by wires , use chokes. Show our noise on oscilloscope.
notsolowki:
the buck converter is set to 5v (its adjustable).
Another source of noise.
Use 9 - 12V transformer and lm7805
notsolowki:
in a few days im going to switch to [url=New Brand No.18M9252 Triad Magnetics N68X Isolation Transformer | eBay?
This one is cheaper