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Home Brew Forums > Home Brewing Beer > DIY Projects > Other > Quick Question drop 5VDC to 3VDC??
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Old 02-18-2013, 01:01 PM   #1
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Default Quick Question drop 5VDC to 3VDC??

I've got a 16 port switch I'd like to use, but the power supply that came inside it (small circuit board) died and I took it out. I kept the thing hoping I'd find a cheap power supply of some sort. I've tested that the thing works with a PC PSU using the 3.3V connector, but that is just too big to be practical.

Now I have found a small 5V brick that puts out 1A and I think it would more than suffice to operate this small switch.

I had thought to just use resistors to drop the voltage, but a quick look online describes all manner of different circuits and many of them claim that just using a resistor would not be good due to fluctuations in current or something.

My brain still wants to think this could be as simple as using a voltage dropping power resistor or something.

Any input?

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Old 02-18-2013, 01:10 PM   #2
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The resistor will work iff your load draws a constant amount of current ( like a solenoid or something), and if you dont mind wasting power in the resistor.

I would look into a voltage regulator like an LM317. It will still burn a bit of power but can supply up to am amp or so and should only cost a buck or two.

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Old 02-18-2013, 01:16 PM   #3
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I may have a couple of those regulators, but I'm not sure how to wire it up. I gotta run out back and help weld some parts. I'll give a google search on how to set it up when I get back. (Hopefully soon...)

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Old 02-18-2013, 04:12 PM   #4
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You can get a "LM2596 step-down module" on eBay for less than $2. That should do it.

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Old 02-18-2013, 04:34 PM   #5
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Cool! That looks like it would do the trick. Thanks!

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Old 02-18-2013, 10:43 PM   #6
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I just impulse-bought some of those. Regulators, caps, and pot all soldered up? For $1.60 each you can't beat that.

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Old 02-22-2013, 12:46 PM   #7
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Homer,
Have a look at All about Circuits for a diagram to hook up a regulator. You can even make it variable voltage if you would like. I use the diagrams on that site all of the time when I am building a project and never had an issue or let the magic smoke escape yet either. Worth a look if your not sure how to hook it up.
Wheelchair Bob

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Old 02-22-2013, 03:42 PM   #8
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Quote:
Originally Posted by Rbeckett View Post
Homer,
Have a look at All about Circuits for a diagram to hook up a regulator. You can even make it variable voltage if you would like. I use the diagrams on that site all of the time when I am building a project and never had an issue or let the magic smoke escape yet either. Worth a look if your not sure how to hook it up.
Wheelchair Bob
That's a nice site! I've tried a few times to learn all about electronics and it has always eluded me. I can play with components and even build a few things with instructions, but I never understood HOW electronics work. I might have to spend a little time going over this stuff again.
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Old 03-14-2013, 01:18 PM   #9
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Quote:
Originally Posted by BetterSense View Post
I just impulse-bought some of those. Regulators, caps, and pot all soldered up? For $1.60 each you can't beat that.
That's what I did. I bought the VERY cheap module from China and just finished wiring it up. Very inexpensive fix for a 16 port switch. I wish it was Gigabit, but hey, it was basically free!

The only stumbling block I had was not knowing that the variable resistor that comes on the module takes a lot more turns than I expected. I twisted this way and that and it didn't seem to do much. Finally I just kept turning in one direction and noticed that it was dropping after all, and then suddenly it was on spec.

I tested 1 port for data throughput and it was great. Then I tested the remaining ports for connection only.

Thanks for the help guys! Other than the kind of long wait for the thing to get here form there, it was very easy and works great!
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Old 03-14-2013, 07:06 PM   #10
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