Author Topic: cheap bench top power supply for IoT projects  (Read 3758 times)

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Offline baastrup

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cheap bench top power supply for IoT projects
« on: January 11, 2017, 11:13:55 am »
Hey.

Any recommendations for a cheap compact power supply for projects with omega2/arduino

My thoughts:
price tag <= 100$
small formsize
variable output
low noise

Im right now looking at the following:
https://www.amazon.de/Lavolta-BPS305-Labornetzger%C3%A4t-Labornetzteil-Regelbar/dp/B019OKC7MU/ref=sr_1_2?ie=UTF8&qid=1484124719&sr=8-2&keywords=bench+power+supply

http://uk.farnell.com/tenma/72-2685/bench-power-supply-1-ch-30v-3a/dp/2563981
 

Online technix

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Re: cheap bench top power supply for IoT projects
« Reply #1 on: January 11, 2017, 11:17:25 am »
A USB phone charger + spliced USB cable or USB micro-B breakout + a small selection of regulator chips (AMS1117-3.3, LP2980-1.8, etc?)
 

Offline george graves

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Re: cheap bench top power supply for IoT projects
« Reply #2 on: January 11, 2017, 11:26:22 am »
Why would an IOT things, thing need a bench top supply?  Then it would become a internet of things+ a bench supply.

I love my korad units.  Dave gave them a negative review IIRC, and I had one blow up on me.  They since fixed the issues.

https://www.amazon.com/KORAD-KA3005P-Programmable-Precision-Adjustable/dp/B0085QLNFM

« Last Edit: January 11, 2017, 11:29:53 am by george graves »
 

Offline baastrup

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Re: cheap bench top power supply for IoT projects
« Reply #3 on: January 11, 2017, 11:33:22 am »
Why would an IOT things, thing need a bench top supply?  Then it would become a internet of things+ a bench supply.
Good question, im totally noob here, smaller might do, thats why all suggestions are welcome :-)
I might just need a dc power supply with variable output and display or whatever such a thing is called.
« Last Edit: January 11, 2017, 11:41:11 am by baastrup »
 

Offline baastrup

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Offline rstofer

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Re: cheap bench top power supply for IoT projects
« Reply #5 on: January 11, 2017, 07:32:49 pm »
What about this one?
http://m.banggood.com/EU-220V-DIY-LM317-Adjustable-Voltage-Power-Supply-Board-Kit-With-Case-p-973391.html

Is it any good?

It's pretty hard to mess up an LM317 project.  This one is pretty cool because it has a continuity test function as well a signal source and a divider to catch external pulses.  The schematic doesn't show how the LED display works so I assume it is an integrated unit with an internal A/D (a panel meter).

I find myself using a multitude of wall warts.  I did buy a Rigol DP832 but for MANY years, all I used was wall warts, fixed voltage supplies and batteries.

 
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Offline JLNY

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Re: cheap bench top power supply for IoT projects
« Reply #6 on: January 11, 2017, 08:31:18 pm »
those generic 0-30V supplies are pretty good. I have used a "Tekpower" TP-3003D and had no problems.

One very important thing to note about IoT and RF projects in general is that it is preferable to have a linear power supply rather than a switching power supply, as linear supplies generate less RF noise.

If you do decide to go the DIY route, be sure to go for a design that has an adjustable current limit-- not just to protect the power supply itself but also the projects you work on! I started out using an old Elenco variable PSU based on an LM317 or something similar, and I accidentally blew up a couple things because although it does have a hard current limit at about 1A or so, the current limit was not variable.

The other route would be to see if there are any used bench PSUs on ebay. HP/Agilent, Lambda, and Kepco are a few decent brands I know of. Proper lab-grade supplies are built like tanks, and can be so hard to kill that they frequently outlive the labs they are used in. They often go for cheap on ebay when old labs get cleared out. Just be sure to shop around to find ones with a reasonable voltage and current range that are within your budget. The pride of my bench is my massive HP 6274B 0-60V, 15A supply. It weighs about as much as a small black hole and the fan's pretty loud, but it will power just about anything I throw at it and has a very clean output.

Regardless of what you choose, always remember to verify the output voltage of the PSU with a decent DMM before you hook anything up to it. On analog panel meters especially, it is not unusual to see ones that are out by as much as 10%.
« Last Edit: January 11, 2017, 08:35:19 pm by JLNY »
 

Offline baastrup

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Re: cheap bench top power supply for IoT projects
« Reply #7 on: January 12, 2017, 09:28:26 am »
I bought the diy LM317 project from ebay "was a little cheaper" I was thinking if it it possible to add a fuse or something to make sure not to go over 1A?
to secure a project?
 

Offline JLNY

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Re: cheap bench top power supply for IoT projects
« Reply #8 on: January 12, 2017, 02:25:32 pm »
I bought the diy LM317 project from ebay "was a little cheaper" I was thinking if it it possible to add a fuse or something to make sure not to go over 1A?
to secure a project?

Probably enough to get you started, and if you plan to stick mainly to microcontroller projects that  may be fine for quite some time. Adding a fuse in line with the output would be a good idea, and definitely also add a fuse on the mains side if it doesn't have one already (you'll have to calculate the current value for the primary side based on your mains voltage and the max voltage of the kit, probably 0.25A or less). When I used to use a supply without adjustable current limiting like that (an Elenco XP-15 kit), I bought an in-line fuse holder and spliced it onto the positive lead on my power cables.

The other issues I see with that supply kit are that it doesn't appear to have an on/off switch, the outputs aren't on banana plug posts (allowing for different leads to be used), and there is no meter for the current. You could always just keep a DMM in line with the PSU to monitor the current, but I actually modified my old Elenco XP-15 to have voltage and current panel meters and an on/off switch.

One issue I had with the XP-15, which I'm not sure will apply to you or not, was that I found that the transformer used to get very hot after prolonged use at higher current. I would keep an eye on it just to be sure when you first test it out.
 

Offline turbotemp

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Re: cheap bench top power supply for IoT projects
« Reply #9 on: January 13, 2017, 09:12:04 am »
LM317 is self-regulating, so output short wouldn't cause a self-destruction. If you are ok with topping out at 10v or so, a small desktop PC is a good host. There's plenty air flow inside to keep it cool. If you're good with programming, you can throw on digital potentiometers and use that same PC to set and profile the voltage.

Worst thing that can happen is the computer will lose power if you manage to short the 12v directly.   
 


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