All you need to know about Linear PSU (Power Supplies) To Build And Fix Stuff - Tutorial Guide

Let's take a look at Linear Power Supplies. These are much simpler than Switch Mode PSU but there is still plenty to learn, We'll put together a small dual positive/negative power supply mostly using parts salvaged from a NiCAD/NIMH battery charger. Of course things don't quite go to plan and it doesn't work! So we have to diagnose and fix the problem. There is some very good advice about the fundamentals of Electronics Repair here - watch it through and you may have a 'light bulb' moment!
CHAPTERS
00:00:00 Prologue
00:02:08 The Battery Chargers
00:07:31 Salvaging The Components
00:27:40 Schematic (Pt 1)
00:32:13 Connecting The Transformer
00:33:24 DANGER! Autotransformers
00:37:01 Rectifier Diodes
00:40:29 Half Wave Rectification
00:42:23 Schottky Diodes
00:46:44 Schematic (Pt 2)
00:48:52 Smoothing Capacitors
00:52:08 Schematic (Pt 3)
00:55:08 Voltage Regulators
00:56:20 It Doesn't Work!
00:57:05 Diagnosis
00:59:05 ** THE IMPORTANCE OF IMPEDANCE **
01:05:25 Fault Finding (Pt 1)
01:06:50 Ohms Law
01:09:14 Fault Finding (Pt 2)
01:18:00 Load Testing
01:23:08 Full Wave Rectification
01:31:41 Battery Chargers (Reprise)
01:38:01 Epilogue
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Thank you
Richard

[@LearnElectronicsRepair]

*Please make sure to watch **59:05** * THE IMPORTANCE OF IMPEDANCE * This is the fundamental principle of all fault finding!*

[@it-sd]

Awesome job! Wonderful explanation, as always. You’re hand-drawn schematics and tutorials are the best-free, university-quality electrical engineering education.

[@LearnElectronicsRepair]

@@it-sd Strangely enough, when I think about it, this statement about source and load impedance is probably one of the most profound things I ever said on this channel 😊

[@it-sd]

Please know it didn’t fall on deaf ears. Well done.

[@bimbim6565]

@@it-sd ppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppp0pppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppp0ppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppp0ppppppppppppppppppppppppppppppppppppp00ppppppp0ppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppp0pppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppp0ppp0ppppppppppppp0p0pp0ppppppppppppppppppppppppppppppp0pppp0pppppppppppppppppppp0ppppppppppppppppppppppppp0pp00p000pppll

[@dfsilversurfer]

@@bimbim6565 hey wake up. !

[@it-sd]

This is one of the best channels on KZbin for learning electronic repair! Thank you for all of your efforts!

[@hullinstruments]

Absolutely loving this content. It Took me nearly 10 years of constant full-time work to learn all of the stuff you’ve packed into a few months! Absolutely splendid! There’s been a real void for in-depth troubleshooting content on KZbin. Previous content creators were either “way to complicated extreme fancy pants stuff” or stuff that didn’t go into enough detail at all. There were a few creators like Marco reps and Diode gone wild who did sporadic troubleshooting projects but it was few and far in between Absolutely love and adore your channel and content. I discovered a similar KZbinr this week who goes by the name “magic smoke“. His content isn’t as well organized and packaged into a learning experience like yours is, but his troubleshooting videos are legendary, extremely long, and detailed. but still to the point where you don’t have to be an engineer to understand them. So his channel is really another super useful tool here on youtube I Would’ve killed to have had both of y’all’s content here on KZbin starting 10 years ago. But I’m just so glad it’s around now!! In six months you’ve covered damn near everything that I would expect to learn taking a 2 year troubleshooting course down at the college.

[@LearnElectronicsRepair]

Thanks! I'll check out magic smoke too - I hadn't heard of him

[@LearnElectronicsRepair]

edited I checked out magic smoke, that's a nice find. re Marco Reps sorry but I can't watch it, it just sounds too much like one of those trailers for films in the 90s and 00s - like 'It was a time for heroes'.... Actually I had another look at some of his videos and my comments abut the audio on Marco Reps was unjustified. 😊

[@timothygolden5321]

I do like electronics, but I enjoy listening to this man as much for his accent, as his details. The details do matter, though.

[@stevecoppin6396]

just started playing with this stuff , very informative. i used to do hydraulics for a living ... the number of times somebody would twiddle ALL the valves at the same time lol

[@carlgradolph9676]

I don't know if you deliberately made mistakes or if you you just covered your blunders well. Either way, they provided opportunities to explain what can go wrong when building a linear power supply (or any other circuit) and how to troubleshoot, diagnose and repair the faults, which is valuable information indeed! Thanks so much for this video, from which I have learned a great deal.

[@brano2yt]

the IC at 19:00 is AN6780 - general purpose long interval timer, contains oscillator + divider (15x flip-flop), maximum time: one week (datasheet can be found by "an6780 panasonic")

[@LearnElectronicsRepair]

Oh no - another HC4060 type timed charger circuit then. This design is getting tedious! lol why do they scratch the makings off?

[@nicklaspersson4687]

@1:26 I was very surprised by how the FBR was drawn. I thought it was drawn wrong or something but it is of course, correct. I just never ever seen anyone draw a FBR as asymetrical like that. It took me a good wile of thinking and redrawing to discover that you actually had NOT messed it up. Good exercise for me.

[@davelowets]

Yea, I always draw them as a diamond shape with all the bands on the diodes pointing to the positive end. The opposite side is negative, and the sides are the A.C.

[@kennyrmurray]

What a great job explaining this stuff to all us amateurs. I want to build a big power supply for my 90V DC motor from an old treadmill so I can build a nice belt grinder for my shop. I bet you’d get a lot of views if you did one like that and a single to 3 phase VFD for us Americans. Thank you!!!

[@jackwilliam2226]

Great vids! Your transformer diagram looked more like a step-up than a step-down, but I am just glad I can actually tell the difference!

[@mickduprez9598]

Awesome tutorial! I loved the structure of starting with almost nothing, testing along with your observations and gradually building in complexity to the final product, great stuff! A next step project that would be good to learn from is a simple amplifier, I get the gist of them but my understanding of how current and voltages apply at/through the base/emitter still needs work :) Thanks Rich 👍👍

[@Martyn-ey9lw]

Just found your channel, used to do instrument repairs for an electric company (NEEB), 500v I/R testers to 30kv I/R test sets to 60 Kv oil test sets and every thing in between, best job I ever had, still have an interest in electronics but don't get much practice these days. You have re-ignite my passion. Thank you

[@christianmusso629]

Great tutorial! I liked both the schematics explanation on plain paper and the actual verify with the scope.

[@chadrussell2933]

Loads of info! Easy to follow! Great video!

[@paulmuff9883]

I do like the way you explain things, please carry on your good work 👍👍👍😀

[@skysurfhf]

You can use termal paste of CPU to see the chip numbers ( marks ) ... Is better than the alcohol 😜 ... Greatings from Portugal 🇵🇹🌟

[@wherami]

So far this is my favorite vid. Really enjoyed this one

[@mahsakashefi4991]

I really really enjoyed this video. Thousands thumbs up, Richard!

[@KB1UIF]

I suspect the filament bulb was for loading the batteries for testing and cycling purposes. Filament bulbs make a much better job of a load rather than LED's that require current limiting resistors and will not work so well at the lower voltages, where as a filament will continue to load the battery until disconnected.

[@jmurph8906]

Superb content Dickie. Chapeau!

[@MsKelvin99]

I love this channel! glad the algorithms recommended it

[@johnmarchington3146]

Thanks for a terrific video, Richard. I've enjoyed all the ones I've watched so far. A friend of mine in the computer club we both belong to (he's the president) had watched one of your ATX power supply repair videos and told me about it. I'm also interested in all things audio as well.

[@brikaf6001]

Absolutely the best explanation i've ever seen

[@henrybartlett1986]

Love your videos no matter how long.

[@jonsdiagnostic5879]

Thank you so much for all you do!

[@paulb4661]

Technically speaking, voltages from about 50 and up to 1kVAC and 1.5kVDC are classified as low, beyond that is where the fun starts, as even air becomes increasingly conductive. Nevertheless, even low votage can be lethal, or mildly irritating, depending on circumstances and the individual under test. Thank you for another great episode !

[@davelowets]

24vac across some sweaty skin can certainly be VERY irritating... 😬 ⚡️

[@ElectronPcRepair]

Thankful for your efforts to teach us

[@HnsxToP]

Thank you for the lesson sir!

[@conwaynoel3715]

Great vid, highly informative. Re ohms law, just cover the required value with your thumb !

[@hiscifi2986]

I designed a few linear PSUs, and one 'fiddle factor' that I found useful was to make the main smoothing capacitor 5000 uF for every Amp designed output. So for a 20A psu you would need a 100,000uF capacitor. The mathematics used the formula C = I dv/dt. This gave a ripple of 1v on the Capacitor, prior to the regulating transistors.

[@d614gakadoug9]

That is a very large amount of capacitance. One significant drawback to "excessive" capacitance is that increases the ratio of RMS current in the transformer to average current. This means you may have to derate your transformer's current rating more than you would with less capacitance.

[@daz41262010]

excellent videos coming from your content :)

[@jordanch68]

A good source for a linear regulated power supply is one of the 'SOLA' type industrial power supplies. In stock form they are available in various voltages from 5-24v DC in various amperage values. The transformer outputs between 50-65v AC if you want to do your own regulation/rectification circuit.

[@TheEmbeddedHobbyist]

A nice dual bobin transformer there, great for mains isolation as the mains and the output windings are on there own bobin so no chance of ever touching. Unlike a lot of the imported units where the isolation is just two layers of enamel coating, putting the input mains and the output low voltage closer than a gnats balls.

[@andymouse]

Squeak!

[@englishrupe01]

How on earth did you manage to measure the proximity of gnats' testicles....or are you referencing a research paper? And how many gnats were injured or suffered in the making of said examination? I have often tried but failed after said subjects expired when my micrometer slipped. ;-)

[@TheEmbeddedHobbyist]

​@@englishrupe01 i have a book called "100 and 1 things about a gnat you wished you had asked your mum" ;-)

[@gregwmanning]

Just found your channel. It is very interesting thanks. Have you discussed the Isolated Test bench in another video, if not I would find that explanation informative.

[@andymouse]

A nice watch...cheers.

[@kwpctek9190]

Bipolar supply is possible on single output AC transfo's. One wire is 0v (common rail), and the other splits to 2 opposed diodes for half-wave to a pair of larger el-caps for both + and (-). Image look-up *many simple 6V power supply*

[@LearnElectronicsRepair]

Thanks, I'll have a look

[@brano2yt]

The circuit is called "full wave voltage doubler", it has the disadvantage of half wave rectifier, but is simple to build. But on center tapped transformer you can use bridge rectifier on the opposite secondary "ends" and output capacitors from both plus and minus to center tap. So you use both half waves to charge both caps.

[@kwpctek9190]

@@brano2yt True, I had forgotten that. Many multiplier cct's (2x 3x 4x etc) use long strings of NP caps with diodes acting as stage blocking to prevent backwards discharge. I think a cheap 20w @ 16v door-bell transformer would be a good choice to about 200ma. They're also usually class 2, so safer is better.

[@T2D.SteveArcs]

Should have used a full-bridge rectifier across the two white wires and black would have been CT or common you would have had plenty of voltage in that case to use 7815 and 7915 .. the scope trace looked that way because you had no load on the diodes and they need a load to switch properly, the 1/10M loading of the scope probe often isn't enough... Steve

[@Dutch_off_grid_homesteading]

Heya that is a nice way to make some project indeed

[@jonathandyble6619]

Hi Richard great vid. Can you tell me if the kaiweets km601 you reviewed has adequate resolution to work well with the £1 sort finder you built? Thanks.

[@mariushmedias]

A few observations ... Didn't see any mention of the idle AC voltage being much higher than AC voltage under load. Very low VA rated transformers will often have an idle voltage 15-30% higher than "under load" voltage. Also, when choosing rectifier diodes and output capacitors, keep in mind that your AC mains voltage is not fixed, depending on time of day it could vary a lot... it's not uncommon to have 250v AC at 2-3 AM where I live, where the default AC voltage is 230v. So account for that, assume the secondary output could be at some point much higher than expected. The 1uF electrolytic on the input in your circuit is kind of pointless. For decoupling, it would make more sense to have ceramic capacitors there, in the 0.01uF/0.1uF/0.47uF range. Electrolytic capacitors filter some frequencies, ceramic capacitors are good at other, so with two different types of capacitors you're better off. One other observation : pay attention to datasheets but keep in mind when those datasheets were written also. For example, a lot of datasheets will say "a 10uF tantalum capacitor on the input would suffice" - they say tantalum because those had reasonably low ESR and 10uF ceramic capacitors were more expensive when the regulators were invented and datasheets were written. Nowadays, 10uF electrolytic or solid (polymer) capacitors exist with specifications much better than tantalum capacitors. So you could use a 10-47-100uF electrolytic on the input that's cheaper than equivalent tantalum capacitor (and you don't risk holes in circuit board from tantalum capacitors going up in flames) Some regulators have specific requirements that must be respected. For example, a "jellybean", very common regulator series, 1117, made by various companies, requires a capacitor on the output with ESR between 0.1 ohm and 1 ohm. Some manufacturers make them compatible with ceramic capacitors, other brands don't... so some people add a 0.1 ohm .. 0.22 ohm resistor in series with a ceramic capacitor when they don't want to use an electrolytic capacitor - even with electrolytic capacitors you have to be careful - some series of capacitors have less than 0.1 ohm ESR at capacitance values below 100uF.

[@LearnElectronicsRepair]

Thanks for the in-depth explanation on capacitors - I openly admit (and accept) I am much more of a fixer than a maker but one of the great things about this channel is that subscriber put their 10 cents worth in to the discussion and we all learn in the process, me included 🙂

[@d614gakadoug9]

Beware of modern high C•V product ceramic capacitors. Some of them have extremely large-magnitude negative voltage coefficient of capacitance. Your nominally 10 µF capacitor rated at 16 volts might be down to 3 or 4 µF or less at 10 or 12 volts. If you want something close to nominal capacitance you may need to operate such caps at a voltage so low you are better off with a "better" cap with lower voltage rating in the same physical size.

[@KB1UIF]

Maybe you could use the lower voltage part of the transformer as a single 5V supply instead of a plus and minus supply?

[@ralphj4012]

Educational, as always. Not sure if you tested current, voltage etc without the dim bulb in circuit. Probably makes little difference at these relatively low currents, but worth a check.

[@LearnElectronicsRepair]

Yeah I bypassed the current limiter off after the first test

[@uksuperrascal]

The Lamp is to test a 1v5 battery before charging, if the lamp can be lit at any state of charge of the battery to be charged, then any battery will charge even nonchargeable AA OR AAA batteries the manufactures recommend you do not recharge, you just have to not leave them on charge, A for to long and B not unattended or to monitor battery heat. Most AA & AAA non rechargeable batteries will recharge 5 to 10 times with a 1 to 2 hour charge of 2 Volts at 100mA to 200mA's.

[@BjornV78]

11:12 you can make a "KGB screwdriver" yourself by using a flat screwdriver, and use thin cutting wheel on the Dremel to make the gap. 12:51 That small incandescent light bulb can have 2 purposes, as a "charge" indicator, and also as a current limiter, because those small SMD resistors alone on the back can't limit the full current that the transformer wants to deliver to a flat battery.

[@brano2yt]

Actually small bulb has a function in first charging slot, after switching the switch to check/TEST position. It loads the battery and by stable or fast dimming light you know the state of battery. After charging a good battery it should shine continuously bright.

[@LearnElectronicsRepair]

@@brano2yt Yeah it seems that charger has a battery test function - and most likely the light bulb is the test load

[@jamescollins6085]

Are you open to recording some footage at the car boot sale as well? I find it interesting to look around virtually.

[@bloothedog4443]

The oscillator setup on that 4060 (pins 9, 10, 11) seems different to me (as many things do 😆). Looks like 11 goes to the usual 2 resistors and probably a capacitor somewhere, but also a couple of transistors?

[@alanrichardson1672]

Perhaps you should mention voltage and current transformers are generally rated in VA

[@gregreynolds5686]

The irritating screws might be to do with certification, depending on the interpretation of the standard. I can see that putting such screws in might be a way to make a stronger argument that hazardous areas are not accessible. Also the possibility that the assembly company is already tooled up for the particular screws, maybe for products where they have a more legitimate use.

[@davidmonk7773]

Hi Richard, what would make one of the bulk capacitors hit 55v and the other correctly 17v after the rectifier diodes? The transformer is correctly outputting 20v 0v 20c 12v 0v pre rectifier

[@Mark_C1]

23:40 A+B is PNP, is the way I managed to memorise the transistor types on those T092 types

[@LearnElectronicsRepair]

Nice little mnemonic

[@Martyn-ey9lw]

The way I remember NPN and PNP from schematics is NPN is Not Pointing iN refering to the emitter, probably doesn't make sense to any one else but that is what sticks in my mind.

[@kiklop2715]

you really need to make oscilloscope for repair tutorial

[@opticwiddly5263]

I second this

[@LearnElectronicsRepair]

I will do that 🙂

[@jamesmdeluca]

Greetings: When displaying the scope image, set your trigger to LINE, 2ms/division, and adjust trigger for a stable display, otherwise your setup is just wasted as it js difficult to follow your discussion.

[@clifforddicarlo9178]

Guerrilla warfare electronics !

[@ElectronPCFix]

What else can I add to make it up to 30 v 5 amp variable Linear DC Bench power supply

[@surgingcircuits6955]

So we figured out that we need a 120-ohm load for our desired test of 100mA. 12v x 0.1a = 1.2-ohms. Since the resistor/load is connected to +12v on one side, and -12v on the other, wouldn't it be getting 24v? Thx.

[@surgingcircuits6955]

Seems like the resistors should have been in series for the load.

[@lrdisco2005]

How to learn about electronic devices. 1. Watch every video on this channel. 2. Buy a multimeter and an isolation transformer. 3. Find broken stuff, take the lid off and start taking readings.

[@davelowets]

1:28:05 It is a.... "FOOL BRIDGE RECTIFIER!!"

[@gregreynolds5686]

Perhaps a filament bulb was used because it was on the 240V AC side.

[@stef2797]

the led's on chargers don't light up till a battery is placed in them to join up the curcuit

[@weerobot]

Cool...

[@BoB4jjjjs]

😎 👍

[@ambersmith6517]

i have a scope that has a problem just like yours it just sits taking up space i did find the problem its been so long but its not any thing big

[@dahmanus2002]

This kind of devices lights up when you put a batteri to charge .

[@akcoord9615]

sorry but this smart meter so you do not have to switch every time you measure ac/cd ampere or volt or ohms thanks for the great videos

[@davidhollfelder9940]

Tantalum cap in reverse .. we could have seen it flame up.

[@glennhuel-qz2cb]

can you suggest a 40 volt dc to 5 volt dc 300 milliamp off e battery transformer circuit end ....

[@corel965]

I startet to watch this chnl from Sorin, but it's so hard to find LINEAR PS without protection can anyone advise me some of them ? Thanks in advance ! :)

[@davelowets]

Next up..... A dual-polarity power supply, that provides at least 3 watts of output current, with perfect symmetry on both rails, stable driving low impedance loads, and, oh yea, it must run off a single polarity 12 volt battery... Yes, I know that there are specific I.C.'s available that do this, but this supply needs to be made from discreet components.. Good luck.... 😬 😜

[@theshemullet]

You should add a tip button to your videos

[@LearnElectronicsRepair]

I do have patreon and paypalme for donations if anyone feels inclined, it would be much appreciated as videos like this one take about 8 hours (one full days work) to get the recorded material and about another 4-5 hours in post production editing to make it all coherent and get the audio level reasonably balanced throughout. Even a €1 donation makes a difference to me. You can send donations via this link www.paypal.com/paypalme/youtubeLER You can make regular monthly donations via this link (until cancelled) www.patreon.com/learnelectronicsrepair

[@theshemullet]

@@LearnElectronicsRepair I dont know how difficult it is but I have seen other channels with a tip button. it makes it very easy as anyone can just send you a tip without a sign up or anything. Might be worth you adding it in.

[@theshemullet]

@@LearnElectronicsRepair actually its called a thanks button

[@theshemullet]

Also it would allow passing viewers just give you a few quid. It might also be useful for you to see what videos you do that are more appreciated. If you get a flat patreon fee, then you dont know which vids people really like/want from you. So it might help with you working out the vids that are most useful to people. its handy to give a like but if someone is willing to give a few quid for a video you know that thats the content that is most appreciated. Just an idea. Hopefully you will add it so we can give you a few euro for vids that we really get the most out of. Thanks for all you vids.

[@theshemullet]

Donation given. Look forward to your next videos. Oh could you do a video explaining voltage drop

[@willsmith4584]

What country is this? It has the same plugs we have in South Africa... I'm gonna guess australia simply because my stepdad has the exact same laugh. He is from Australia

[@LearnElectronicsRepair]

Gran Canaria (The Canary Islands) - part of Spain. I'm originally from the UK

[@wherami]

Its to keep out the average muggle. Same level of security that keeps average muggles out of operating systems. It defeats and deters 90 percent. Per your special screws comment

[@LearnElectronicsRepair]

That would make sense if you couldn't buy these little screwdriver sets for almost nothing from almost everywhere. Anyone who does any sort of DIY (and that's most of us) must have a set 😏

[@wherami]

@@LearnElectronicsRepair you underestimate how lazy the general masses are. There is little to stop the motivated and dedicated.

[@LearnElectronicsRepair]

@Mr Guru haha I was clearly ripped off LOL 😆

[@LearnElectronicsRepair]

@@wherami Very true 😁

[@QARepair]

👍 but you speak so fast or if exact normal and then suddenly very emotional fast😅, sorry, I barely understand, I'm not english

[@johnboothman1235]

useless waffle