hpr-knowledge-base/hpr_transcripts/hpr2044.txt

Episode: 2044
Title: HPR2044: Bring on the Power!
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr2044/hpr2044.mp3
Transcribed: 2025-10-18 13:38:44

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Hi, this is Ken, just a quick reminder not to forget to go and vote for HPR on the
podcastawards.com website, thank you.
Hello, this is Enwai Bill, and I'm back with more electronics, goody talking stuff.
Today I was going to talk about power supplies and getting power to your project.
Years back, I mean when I was a kid, I would use batteries, that's all I had, you know, sitting around.
So like double A's at 1.5 volts and you can stack them up until you get to whatever voltage you need or 9 volts.
I used a lot but when you start getting into like LEDs and electronics you're going to want 5 volts or 3.3 volts.
9 volts is going to be too much for you.
Next, an expensive step I guess would be to go find wall warts which come with, you know, all your devices that black square,
that you plug into the wall and then it goes into your device, I'm sure you're, your phones have them.
I'm looking around the room right now, there's a lot of equipment that has a wall wart.
So the transformers right there at the mains and it transforms the mains voltage.
It's 120 here in the States and it'll transform it down to whatever voltage that device needs.
You know, it could be 3 volts, it could be 5 volts, 9 volts, 12 volts, whatever.
The wall wart is matched to the equipment that it's being sold with.
But if you get a small collection of these and I have it down in the basement, I have a milk crate that's just full of old wall wart power supplies.
And sometimes I got to go dig through there and find the right one.
Recently I did that, I did a HPR about a oscilloscope kit, a DSO 138 sometime back.
And when I wanted to bring that device to the lug, it wanted 9 volts.
So I went digging through that milk crate to see if I could find a 9 volt wall wart that would fit the socket of the kit so we could troubleshoot it at the lug.
I didn't have, I did have 9 volt wall warts but I didn't have one with the proper barrel socket on it.
Another thing they sell, I haven't seen one in years but I do have one around somewhere but I lost the attachments.
What it is, it's a wall wart power supply and on the power supply it has a switch and I think mine runs from 3.3 volts up to 24 volts and it hits steps in between.
So 3.3 and I think there was 5 maybe or 6 and then a 9 volt and then something a little higher I haven't used it in quite a while.
It might have been 16 volt, it just steps up in little steps and you can switch that switch for whatever project you need it for.
If you start getting a little more series about electronics, the next thing you're probably going to want to bench power supply because you're going to have all your electronics out on a desk somewhere.
And you're not going to want to just, I did, I used batteries forever like a breadboard with a 9 volt clipped into it and then I'd have to reduce the voltage with resistors.
And it just, you're going to want to step up to a power supply at some point and power supplies are fairly inexpensive and I'll get into, well, they can be fairly expensive as well.
What I have is a tech power, I think it was like 50 bucks, it's a cheap little 0 to 30 volts DC, 0 to 3 amps.
It's a switching power supply.
Switching power supplies are less expensive. The other style power supply you can get from your bench is a linear power supply.
And let me just talk about the differences between the two.
The switching power supply is going to be small.
Light weight, fairly lightweight, I mean there's different size ones and you know, but mine's pretty small.
It's six inches high by maybe three and a half inches wide and depth is maybe 10 inches.
You guys can convert that to whatever other weird numbers, cubits or whatever you guys use.
And then it's on the front is voltage and current two knobs and course and fine.
So you can go from zero up to 30. This one actually puts out like it'll do 31 points something but probably under a load it would pull that back down to 30.
And let's say you need 9.7 volts, you can go course until you get to nine and then you can use fine until you get to that 0.7.
So it's coming handy. The only thing with switching power supplies are they are switching at very high frequencies inside them.
And sometimes they make this really high pitched wine and some people can hear it and some people can't.
I can hear it. This thing drives me crazy. It's I don't know if anybody remembers like an old tube TV when you were a kid or something a big tube TV.
Did any of you ever hear like a high pitch wine coming out of it? I used to have to go up and smack the side of our TV and that would go away.
I don't know what the smacking was doing like resetting a tube or something but I can hear this high frequency switching and my wife can't.
I had her in the room one time. I can't hear this. You can't hear this and I'm switching it on and off.
So if you're susceptible to hearing this like a very I can't mimic it because it's higher than that.
Switching power supplies might put out this sound.
So the other type of power supply would be a linear power supply and what those have is large transformers in them.
Sometimes it's a toroidal transformer. Those look pretty neat. Look up a picture of those. It looks like a big donut with copper wrapped around it and the taps come out.
And what those do is they generate their voltage and they will use physical relays in there and different switching to go through and give you whatever voltage you're trying to dial in.
However, these are usually large units and they can get hot and then they need cooling.
So you're either going to get this switching power supply very high frequency buzz you're going to put up with or you're going to have a linear power supply with no buzz but sometimes a big fan might kick on.
So those are pluses and minuses.
Another thing with power supplies and I wish I got this just like fair warning.
My power supply when you turn it on its life it's the the voltage is going to the end of the probes I wish I had a button on this to turn the output on and off.
Because sometimes I'm sometimes I have the probes hooked to a piece of equipment and I go to change the voltage.
If you have a very sensitive piece of equipment and the voltage is always going to the end of the probes.
You don't want to overshoot when you're using your course knob if you if you got a 3.3 little you know I don't know or do you know or something you don't want to move that course knob and go up into four volts just for second by accident and then come back down you probably start frying things.
So and actually this this did bite me once a previous HPR again the one with the DSO Nano 138 a silisope kit.
If you listen to that episode you'll see that I got into trouble with the board and I may have fried something and it was because of this power supply was because of me but the way I was holding the probes because there was no way to turn off the voltage of the probes without turning the whole unit off.
I was holding live probes in my hand and I touched the board and you know bad things happen so that's one thing I wish.
I mean if I get another power supply I'm definitely going to make sure it has an output on off button.
Turn the output off you do all your dialing in you figure out what voltage you want make sure everything's hooked up and clipped right and you just hit one button and your voltage comes out nice and clean.
We should talk about clean some cheaper power supply they might have overshoot or undershoot when the voltage is applied if you want we'll just use nine volts.
Just research a power supply that you're going to buy and figure out the overshoot undershoot and if it's acceptable to you if you want nine volts and the power the cheaper power supply you have you hit the output or you turn it on and it overshoots to 10 or 11 volts and then settles to nine very quickly.
But you still have that overshoot of voltage there so just be warned figure out what class of power supply you're going to get into.
I mean I'm sure if you're into electronics to the point where you're researching the spec sheets of this stuff you know what you're doing you know.
But I'm just warning to for if anybody like hears this and gets inspired to step up from you know using batteries to getting a bench power supply I'm just giving you you know some gotchas or some things to look out for.
So when I got this little I should take a picture of these I can show you these yeah I plural so I'm going to talk about another one in a minute.
When I got this and I heard that high frequency noise I could hear it my computer room is about maybe 14 by 10 feet.
Now anyways the I do electronics in one corner of the room and the computer is in a complete opposite corner of the room and even when I'm sitting over at the computer I can tell if I forgot to turn off the power supply because I'll just hear that high pitch wine.
I did start researching linear power supplies and I did find one that I was going to buy and it's good to read the reviews because that one did say this the fan kicks on once in a while it's like a jet engine so so far I've just been putting up with this bench power supply that I have.
It's a little cheap unit someday if I upgrade I may get another switching power supply and I'm definitely going to get one with the on off button or the output on off.
But I'm going to research better and see what the high frequency noises that comes out of it read some reviews and see if I can get a better one.
Another power supply that I recently ran into and this goes back once again to that you know I bought that $22 oscilloscope kit.
You know innocently enough let's put together a kit but it's been hours and hours of troubleshooting which I've been a lot of fun.
The troubleshooting has been fun but that $22 kit gets me on Amazon one night and I buy another $100 power supply so it's in front of me right now.
When I said earlier that I looked in the basement for a wall wart to plug into this kit so I could bring it to the lug and we could troubleshoot what might be the problem with it.
I didn't I couldn't find a wall wart so I didn't know how when I brought this board to the lug how we were going to power it to even like stick a meter on it and try and figure stuff out.
And I'm on Amazon and I'm looking for I think I was looking for one of those the wall warts that you could switch back and forth which I have one but I don't have the different barrel ends.
It comes with a whole bunch all the different barrel ends you need and then the actual wall wart wires itself are just two prongs so you pick whatever and you need whatever diameter and stick it on those two prongs and it gives you that round barrel.
Oh another gotcha I just thought of this some of those barrels the outside is negative and the inside is positive and some of them it's the other way around the inside is negative and the outside is positive so always take a meter when you get a random wall wart and figure out which is positive and what's negative because you don't want to feed something backwards.
Anyways the $22 kit gets me to buy a hundred dollar power supply this is also a switching power supply and surprisingly enough this one makes no noise I can't hear any noise but it is the size of a multimeter it's a 30 volts at 1.6 amps and it's a little power supply that goes in my hacker bag now so now the hacker bag has its own power supply.
It's made by tech power it's it's a tp 3016m so let me turn it on so now you know that mobile hack space that blue hacker bag which I did a hpr years years back about like what's in my bag I talked about this it keeps accumulating interesting things and this is a recent interesting thing that it got so I'll take a picture of this or maybe link it in the show notes.
Let me plug it in here and turn it on yes plug it in that's one of its downside it's been pretty good there's no noise to this one I got I'm holding it right up to my ear now it has a nice big screen and it's it has a backlit it automatically comes on it's white this so far it's been a cool unit you you hit enter and then you have you know up down left right and you can change your voltage your current and then it does have the output on
off it's a big looks like a power button but it's not a power but it just sends output to the output did that make any sense yeah I suppose it did like a redundancy output the other thing it will do it has two USB ports so you can charge a phone on it or you can run a our pie out of this thing so you could five volts at two amps so this has been a pretty neat portable power supply the only downfall for it is there's no on off switch I don't know why they didn't put a switch
or a soft button the only way to turn it off is to pull the plug out so what I did was I ordered the the power for is like lamp cord if you're familiar with lamp cord the two wires going and some lamps you can have a little tiny rocker switch or a little roll you know switch that you keep rolling to turn the light on and off so I'm going to modify this cord that it came with I already got the rocker switch it's just an on off up down red button and I'm going to cut one of these wires in here I'm going to I say I'm going to find the hot wire in
put that on the switch but this is the type of cord where you can just flip it back and forth or plug it either way in the main so
one of these wires is going to have a switch on it so I don't have to keep plugging this in and out if something doesn't work for you find a way to hack it
it also has a dedicated button for USB you press that it turns green it automatically you might be up at 30 volts but it automatically brings things down to five volts at 2.5 amps so
that's a safety feature so you don't blow up your phone or whatever you're doing with USB the only thing this won't do is go that completely down to zero volts
it's it's like one it's like 0.3 let me try and do it right now set my voltage yeah 0.3 it'll only go down to 0.3 volts it won't go to
completely to zero with the dial button of course it goes to zero if you turn the output off but if it's important for you to let me
if it's important that you have a power supply that goes completely to zero this this isn't it but but it's so cool it's like it fits there's a part of my hacker bag which is supposed to be
where you put like a thermos and maybe your sandwich this it's like a tool bag I got it I was at some like electrical convention or something
and the raffle ticket I won this weird little bag and it's a tool bag you put tools there's pouches on the outside the inside
and then up at the top is a pouch where you're supposed to bring your lunch to work I guess so it's a it's a little
bagged area that has some like a thermal lining in it so it'll keep something cold or hot
that's where I put all my meters it's a nice little padded area and I just stack them up sideways
so this the unit is in there now and now that awon the B35T is in there and then this tech power stacks in there
nicely and then right next to that is a portable butane soldering torch so that fills that compartment nicely however I am running out of
room in that hacker bag if I get any more tools something's gonna need to be done oh and I just remembered one other cool
thing I actually linked this to I'm thinking about getting it uh I'm sure you all know what a breadboard is and
you know you're you put your through hole components and you can build up and test something before you want to
go and put it on you know actually solder it to a board or go and etch something I saw one recently
it was on eBay I think uh it's just your normal looking breadboard and you can use the device
it's gonna come with with any breadboard and on a breadboard up atop and at the bottom there are two
sets of holes and that's where you would put like plus and minus like you might put a nine volt battery
and put the plus and the minus in there and then all along the breadboard on the bottom you have a plus
you have a negative and a positive and you can just bring jumpers out to whatever device
needs some power this seven dollar item that I saw on eBay it's a breadboard and then at the end
is a little device you clip on and it goes into the top and the bottom those two rails that provide
power out down the breadboard and then on that it you know it plugs in with a wall wart and then it
has some power like power conditioning rectification and then there's a little switch where you can
have zero volts like off or you go one way and you got 3.3 or you go down the other way you got
five volts so that's perfect for that would be a perfect upgrade for the breadboard that I have now
where I have to run leads out or alligator clip onto jumpers and stick it into those uh those two
power rails so and it's seven dollars like seven dollars delivered out of China I don't know how
stuff gets here so cheap sometimes so there you have it it's just uh I thought I'd just do a quick
HPR while I was sitting here at the bench with a couple power supplies out and just uh talk about
my experiences with them and if you're in the market for a power supply I hopefully you got
something out of this like what to look for or what not to look for so if anybody wants to chat on
GNU social slash identical I am ny bill at sn dot yeah ny bill at sn dot gumbunky net dot net
email is ny bill at gumbunky net dot net email is ny bill at gumbunky net dot net
and as always we could have a conversation in the hpr comment section if you'd like I'll
check back with that okay until next time guys
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