Circuit Skills: Power Supply

[@Alex-ck4in]

Ive been coming back to Colin's videos since I was a 15 year-old when these videos were first released... Thank you Colin for helping me realise my love of engineering!

[@youfrancis]

Collin Cunningham's videos never cease to impress, entertain or enlighten. He speaks with a cadence that is both patient and lucid. Frankly: I could only wish everyone was as good a teacher as he is.

[@dancoulson6579]

I love it when I click on one of these videos. As soon as I hear the familiar background music, I immediately pause it, turn the TV to mute, and get comfortable. You always know you're going to learn something interesting!

[@rexjuggler19]

This is how to make KZbin videos. If your KZbin is over 10 minutes, you need to re-think it. I stumbled on these just last week. These are probably the best on electronics out there. I have viewed other popular ones, but who has time for 30-60 minutes on a topic that can be effectively covered in the time Collin does these? This one is 7 years old. It is still relevant. I hope he still makes videos. They are engaging, provide the information I am looking for, and don't consume extraordinary amounts of time like others. Thanks Collin - 7 years after you made this.

[@madhatter2k]

Colin, you have style. Loving your work. Half the time I don't even care about what you're building, I just like your presenting. OK, so I do care about what you're building...

[@salihtaysi]

You and your videos are awesome man! Also, watching you talk about something you're passionate about is so attractive

[@Hatimoooo]

I wanted the PWM "Circuit skills" because I love your videos !!! Thanks Mr Collin

[@RetroGameTech]

Collin's electronic vids are excellent! They're really interesting and I always end up learning something new. More like these please, Make!

[@geofreyr]

Collin, your videos are excellent. Your presentation style is very clear and easy to understand, thanks!

[@MrLespaul1963]

Thanks Colin...I'm a musician (not my day job) that got bit by the DIY bug. On top of that, I found out how much the bits of gear cost to build as compared to the butt raping retail that places like Guitar Center charge and looking inside at the circuitry, I realized that this stuff isn't that complex. You, and a few other KZbinrs are my bridge to realizing my dream of building my own preamps, power amps, stompboxes, pedal board switching loops ...you get the idea. Have you published any books or manuals with basic projects that will let me build, for example a push pull, Class AB 20 watt amp using all solid state with a preamp that allows for adjustment of the bass, mid and treble bands. I'd be happy with a passive three band Eq that simply rolls off the treble, mids and bass in their respective ranges...sort of a mixer, but for frequencies or a low, high and all pass kind of tone control circuit?

[@HazeAnderson]

i put mine in a large plastic case I bought from Radio Shack (yes we still got one!). I cut out a square on the front that extends across the front of the top and covered the top with some protective mesh. This allows access to the PCB mounted binding posts and prevents hands from touching further back than the PCB mounted potentiometers. I finally added two digital voltmeters to the front sides. 👍

[@holdmybeer]

he has the most relaxed way of teaching i have ever seen, and i love it!

[@eelcogg]

He didn't say he is usign those, he just wanted an example of a circuit that needs both positive and negative rails. You are right about the 'newer' rail-to-rail devices, they make life easier :) Another example would be high-end transistor audio amplifiers I guess, but they seem to favor much higher voltages, both positive and negative.

[@yoanmilenkov]

I know nothing about circuits, but I still watch those videos!

[@gelfling6]

@LightSwitchr The supply Colin assembled, is fixed to 115V input, so you would need a 230V primary, 12.6V 2-amp Split secondary (3-wire, 12.6-GND-12.6) transformer, and at that level of voltage, a enclosure,nevermind electrical tape over the primary wiring. Also a 230V primary transformer might not mount on the board as the 115V one does, though you could still run the wiring to the secondary points on the board.

[@mikado387]

i miss Collin please come back you're amazing

[@RickTrajan]

He's still around somewhere just look for him

[@mikado387]

Actually , i want to meet him, since im almost as crazy interested in electronics as Collin himself XD

[@supernewuser]

You need to realise that he's aiming these tutorials at people who do not already have these kinds of skills. His cadence and facial expressions are so the viewer feels like they are learning along with him.

[@Bravo1989Tango]

I almost forgot why am I subscribed here, then I saw a new Collin video is up.

[@CampKohler]

@StoreFood In a pinch, you can always use two wall warts and swap the wires of one to get the two different polarities needed by a ckt. You wouldn't want to do that if something bad would happen if only one voltage was present (one of the wall warts might get unplugged accidentally). If you are using two metal-cased supplies where the negative is attached to the case (meaning the supply is not "floating"), then you would have to make sure the cases never touch each other or ground, else sparks.

[@chuckaedw]

Awesome video as usual. I just wish you would of put it in an enclosure at the end.. Still a great one, keep 'em comin. I always look forward to the circuit skills videos.

[@DantalionNl]

Dont forget that the switching frequency of your switching power supply can create noise on the power line which is detrimental to an analog synthesizer!

[@ecv03]

And my Ham Radio.

[@fomalhaut9]

And my effects pedals

[@danielfrei6213]

we've been watching you with great interest, Mr anderson.

[@xasdrubalex]

@FrancekPirosrancek it depends on ic's, i think in the kit there's a lm7818 and a 7918 and they provide 1Amp with heatsink.

[@blva888]

Again the only reason I'm still subscribed.

[@WaterRabbit]

Great video, Thanks MakeMagazine and Mr. Cunningham. Multi Multimeters, Mega Multi Multimeters

[@CampKohler]

@BunnySk8rProductions Two designs: Charger feeds batt which feeds ckts (complicated) or when the batt dies, remove it and charge separately. Use a DC power supply ("wall wart") of a few volts more than the batt volt, thru a resistor, to charge the batt, then put it back in the ckt. The resistor is sized (in ohms) to limit the charging current to that which won't overheat the batt (it absorbs the diff between PS and batt volts. Start large and reduce ohms until max charging current is reached.

[@0h2ezy]

Colin! Where did you go? Your videos have alway been my favorite to learn or develop electronics from. "Make" some more please :)

[@LReBe7]

About the linear vs. switchmode issue: you must always be aware of the ripple on the output of a switchmode psu!

[@D4no00]

the biggest advantage of transformer is that you can bash it in the head of the guy complaining about switchmode converters.

[@James_Haskin]

I feel like I've learned more from this video than any other circuit video. Keep em coming Collin :D

[@321reh]

Always Interesting and NEVER BORING,,,Another Great Video From MAKE,,,Thanks Collin,,,,,,Best Regards from MR.OHM!!!

[@monstergarage2]

@davidenelson It's because the capacitor store some more power upping it up to around 17 volts because voltage regulators need a little more power then they output.

[@Atwenty3]

The only reason I'm subscribed to make magazine

[@Orcinus24x5]

The transformer is rated at 12.6v AC, not DC. When you rectify and filter an AC source, multiply by 1.414 (or rather, the square root of 2) to get the approximate DC voltage. This transformer, when rectified, will produce ~17.8 VDC, which is enough to allow for the voltage dropout of the LM317/LM337 at 15 volts. However, the heatsinks included in the kit are grossly inadequate, and will not allow 750mA to be drawn from the regulators (which are actually 1.5A rated) for more than a min. or two.

[@CampKohler]

@LightSwitchr The number of turns of wire in the transformer primary is designed to limit the amount of current that flows in the primary (even without using the secondary winding). Putting a 120V unit across 240V will burn up the primary, because there won't be enough inductance to keep the current in check. Using a 240V on 120V won't burn up, but it may have weak output under full load. Just look for a kit manufacturer in your own country, so that it is compatible without worrying.

[@thewii552]

@CampKohler or you could use a chisel tip. Or hold the iron sideways

[@di4352]

Every time he builds a circuit he has the most awesome geeky background music!

[@CampKohler]

@ZboneWalker There are lots of videos on PCB making on KZbin. Some are for fairly complicated designs. For simple stuff, you can cut strips from electrical tape, stick them on the copper where you want the traces to be, and drop it in etching solution until the unwanted copper is eaten up. Do it all on paper first, marking where you will drill the holes for the parts, etc.

[@CampKohler]

@ZboneWalker Oh. What can I say? You lay out the parts on the board so that they fit nicely (don't physically interfere, heat from one part doesn't cook another, noisy ckts are separated from sensitive ones, air flow isn't blocked and so forth). Then you draw traces with a pencil (or two colors if it is double sided) until you have you connect everything with the least number of feed-throughs and the most direct runs. It's almost art. Beyond that, do you have any specific questions?

[@ZboneWalker]

@CampKohler i know all of that stuff, but i mean the desingn of the board, i mean copper traces to be placed smartly so the board is as small as possible

[@yoy58913]

this guy is amazing! !

[@rodolfomaduro8157]

redcinos Yeah! He is so ugly yet so cool! How that is possible?

[@CampKohler]

@jakuba8 Negative voltages are not really a separate thing anymore than "water going into a hose" is different from "water going out of a hose." Pressure and flow are the same, just in a different direction. We usually use positive as the "hot" side of a supply merely out of tradition. Benjamin Franklin thought positive flowed out and negative flowed in (like air or water), but he had them backwards, so now the arrows in diode and transistor symbols are reversed and always will be.

[@w0mblemania]

@3:10 Super graphic explanation of the transformation and rectification process. Thank you!

[@CampKohler]

@uut0 Many power supplies are built like you suggest, with a mains/line cord, especially for expensive portable use devices such as laptops, etc. However, it costs extra, and when the device is likely to stay plugged in and is being built to a price, they elect the cheaper two prongs. The Bell System, recoginizing the "easiness" of which you speak, supplied 2-ft-long 3-conductor extension cords to allow no-cord wall warts to be plugged into tight places.

[@mariushmedias]

Yeah, just checked the manual on site. The transformer is rated for 12.6v DC in the manual - I don't see how the kit will do 15v @0.75A as advertised, especially considering it's not doing full rectification of the AC voltage, but rather uses only two diodes to chop one side of the AC voltage.

[@legogunguy001]

@TheEMan1997 not exactly you need a combination, because anything less than 40 volts can not draw enough current through you.

[@CampKohler]

@j7512 Plastic enclosures reduce the design precautions required to keep line voltage away from the user. However, metal is more rugged (doesn't crack when impacted or melt from component heat) and provides shielding, i.e. keeps signals in and noise out. Plastic is quicker and cheaper to build with. "You pays your money and you takes your choice."

[@Pygar2]

@mewmaster151 I know that old picture-tube type TVs made a high pitched sound like that. The "flyback transformer" that controlled the beam, made an audible high whistle or whine that you just had to ignore. And the older electronic flash units for cameras did too... may still, for all I know. So it is more than likely the items are actually making a noise you can hear.

[@fairyheli2]

@mtj770 our 3 phase is 415v, I was talking about household electricity from a socket

[@kolby4078]

It is only using half the sine wave pear output. That is why it only uses two. what you are thinking of is a bridge rectifier witch would flip all the waves positive. What this does is take one side of the original sine wave and just smooth that and then do the same with the other side, thus making it supply positive and negative voltage.

[@lingcheng8286]

How to correctly use multi meter to test the component burn or broken on the circuit board ?

[@MatthiasDeSater]

Finally! Another Collin video!

[@Orcinus24x5]

Nope, you don't need a special type of pot. Just use the same value as the ones in the kit, 2.5 Kohms. You can even use a dual-tracking pot for greater convenience (two pots affixed to one shaft), or a pair of multi-turn pots for greater accuracy.

[@latzobear]

your videos are wonderful

[@chems]

single diode rectification? pretty cheap and crap

[@ankdoeslego9731]

You wouldn't get -15v with full wave rectification.

[@AbsoluteTrash_]

the problem is linear regulators are very inefficient

[@laszu7137]

Making switch mode power supply that is good enough for audio application is very hard. The problem with this is the transformer doesn't have connection in the middle of secondary winding. With transformer that does have that you can make symetric voltage much better.

[@CampKohler]

@thewii552 The tip is likely bent to get into tight spaces. In this case, it allows the tip to be placed flat against the work (as opposed to just touching it with the tiny point). The more intimate contact allows better heat transfer (lower thermal resistance), so the joint heats to soldering temp. quicker. Quicker is better, because the glue that holds the traces to the board doesn't cook as long; ditto the components. That is better than using a big blob of solder to improve the heat flow.

[@alexandraboehmke2102]

What's the song playing around 3:00?

[@megaman1025]

I didn't remember that "Circuit Skills" was Collin's show, so I didn't know what to expect when I clicked on the video, then I heard Collin's theme song and I thought, "YES! Collin's Lab, haven't seen one of those in a while!"

[@Dth091]

@TheSupertecnology Actually, only a few milliamps can kill. Depends entirely on where it is applied. Larger voltages means more of those amps can pass through you, causing more damage.

[@fegolem]

Yea! Collin! Good to see you again. Thanks for the vid.

[@fairyheli2]

@Whisper6911 just regular caps, some have 2 wires on one side, others have one on each

[@jvcrules]

To create a full bridge, yes, you would need four. But this PSU uses 2 half bridges (1 diode each) to get both positive and negative voltages.

[@nahueljo]

Collin! your videos are by far the best on this channel. Switching power supplies are indeed very interesting. However, given that the input and the output circuits are not isolated from eachother (not sure isolated is the right word), this change of frequence that it creates generates harmonics which increase the current in the power lines. I don't know how it is in the U.S. but in Argentina this reactive power is CHARGED if not corrected. Of course, if you use a lot of these power supplies :P

[@TheDrjodi]

could you do a video on using class A, B, C, or D power sections? like what is found in guitar amplifiers or p.a. mixing boards. thx

[@blva888]

@CampKohler a high intensity LED and a battery or dc power supply. Oh the flash should be variable and no multivibrater or 555 timers involved.

[@jamj30]

Collin for President!!! As usual good episode.

[@thewii552]

whats with the bent soldering iron?

[@CampKohler]

@blva888 Specify what load is being flashed and what voltage it has to run on. Some lamps have built in flashers and require zero circuitry to use.

[@bretdavis8097]

So if you have a +15V terminal than if you were to connect a load between that terminal and the ground terminal, you would have a 15V drop across the load. If you were to connect a load between the -15V terminal and the GND terminal you would have a 15V drop across the load (with current flowing in the opposite direction. You could connect a load between -15V and 15V and get a voltage of 30V dropped across the load.

[@BunnySk8rProductions]

@matthewtchernev123 4 leds and 3 fans the lights are powered by 2 AAs and the fans are also powered by 2 AAs, the radio is 3 AAAs

[@numex106]

@rockybyt it's okay because it has a built in resistor (on the board)

[@eddieh74]

Hi, does anyone know if in one of these I can replace those trim pots with regular pots so I can put this inside an aluminum enclosure, or do i need a special type of pot, or maybe need to add another component? Thanks.

[@fairyheli2]

@logos2600 we use 240 as you only need a quarter of the copper, but we are smart enough not to electrocute ourselves with 240, we use 415v for big appliances

[@RefleX525]

I have a Variable DC power supply that goes from 0-18v and 0-3 amps so is there no need for something like this kit in the video?

[@Arazand]

Since this is posted last year you have probably already read this, but switching PSU's are in general more noisy, as in PWM instability have some procent less clean power, the best way to describe this is with a battery that give a constant volt-value when filled up. A linear supply give a very close constant volt-value, while switching supplies although more effective give the least constant volt-value of the three. That makes a switching supply bad for sensitive equipment, such as audio.

[@Techmatt167Official]

is it kinda confusing when there is nothing marked on the pcb for the componments, but you read the directions

[@med6402]

Can someone explain me how to get grownd gndfor example an led suplied with 5v from one side and ground to another where can I get that ground???

[@dwilki1174]

Can anyone tell me the name of the device Colin uses to hold the PCB while he's soldering it?

[@morlanius]

would it be possible to replace the pots with a transistor like a jbt which could be controlled by pwm or a dac to make this controllable by a microcontroller?

[@warriorchild]

Hi Collin's could you make on of these series on OP-AMPs?

[@Techmatt167Official]

@BunnySk8rProductions are the leds and fans separete

[@Orcinus24x5]

Unless you work with devices like opamps that require a positive and negative supply in relation to ground.

[@XIAOTIANism]

usually you can have isolated outputs by using isolation transformers, which gives you floating voltages on terminals.

[@CampKohler]

@blva888 A pot could be used to set timing, but there has to be a circuit to allow it to do that. That would be a multivibrator, 555 or some other timing ckt.

[@nahueljo]

Finally, a Collin video!

[@fairyheli2]

@mtj770 we apparently have 230v 1~ but no one has told the voltage, the voltage at my house is 250v 1~

[@kazimierz198]

Great video and soundtrack. Is there a way to get some Collin's music?

[@Xwozz]

Can you use it with 2 positive supplies instead of 1 postive and 1 negative?

[@CampKohler]

@sammyc45 You put an ammeter between the amp and the batt and measure it (or read the name plate). You may not read the peak demand from short spikes of loud sounds, but putting a large (electrolytic) capacitor across the 12V will let the cap supply the spikes so that the PS doesn't have to be so monstrous. Nevertheless, it will need to be a hefty, expensive supply. I don't get the cig lighter thing, because it gets its power from the batt. (And please rewrite that last sentence clearly.)

[@blva888]

Collin can you talk about how a simple flasher circut works?

[@fcimeson]

@Nadrealis Ya well I can't find the exact one I have but here is one for $13 (at my local store). PWR SUP QUAD OUTPUT 3.3,5,12,-12 Switching (Open Frame) MAP110-4300 (can be found at digikey and Sayal)

[@MadK306]

Can you use that for the color organ or is there any power supply included in the kit?

[@lucasmontec]

COllin collin collin! I missed you man! Make moar vids bro, you are my inspiration!

[@GeoN0JRJ]

And...Switching supplies are a lot more noisy in the RF domain which can sometimes be a real problem. Nice video. Thanks!

[@TheEternalHermit]

Don't you think you should put the links in the description to the products on the Jameco website? It's inconvenient having to go and search for it.

[@ZboneWalker]

Collin make a video on desingning circuit boards... I did a circuit board reacently and i found it really difficult to get everything going smoothly you know?

[@zannatulraiyan6764]

how did u changed the output value ? was it a pot or regulator or something else ?

[@matthehat]

I wonder if I could buy this kit from Jameco and then substitute their transformer for a 240v > ±15v transformer. I only ask because I can't find anyone in the UK who makes a board that does exactly this

[@alexisperez7654]

I'd like to start off by saying my knowledge in the field is very limited. However, can anyone here design something variable voltage or wattage capable of going down from 7 watts to 250 watts at a maximum of 30 amps? Something with a momentary switch for e-cigarette use. Any info would be great. Thanks!

[@thesymphoniccinema]

Why only half-bridge rectifier?

[@Ritzz45]

because the other half is received into '-DC'

[@mrjohhhnnnyyy5797]

Ayy Gee Well that one has 3 wires, so it has center-tap, thus you can use tap as ground and connect other two to a bridge rectifier > higher efficiency, but cost is higher too

[@CampKohler]

@nahjos Yes, modern commercial building wiring must have beefed up neutral wires to handle the harmonics from all the PCs plugged in if more that one or two. Lot of people ignore this. In U.S. most residential power meters don't register reactive power that motors, etc. draw AND GIVE BACK TO THE LINE, just the actual power used up. Pwr companies will use correcting caps to lower reactive pwr so pwr isn't wasted running back and forth from this. Read the Wiki article on Electricity Meter.