AC to DC Power Supply - Breadboard to Prototype board.
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- เผยแพร่เมื่อ 26 ก.ย. 2024
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With a few mistakes along the way....
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Positive video from a clever guy just trying to help and be honest . I enjoy all his videos
The diodes in the bridge rectifier is the source of the voltage drop. Thank you for not editing out the mistakes you have made during this project. The troubleshooting tips are orders of magnitude more informative than the supply itself. Great video!
Thanks, I appreciate the feedback.
I second OSHbots. Great vid.
Mr Lorton, I just want to say that your videos on electronics and design are, IMHO, the best out there. I really appreciate all the time you put into making quality videos that detail every aspect of the design. It's really helpful for padawans such as myself to see the process -- even the mistakes, which are often times more helpful than the "perfect product design" videos. Keep up the great work!
Thank you for the lesson and sharing your learning curve. At 67 I'm new to working WITH electronics, as opposed to just being an end user. It's quite a challenge, but worth every bit of the struggle.
Great video, from concept, thru design, bread boarding, PC layout to build and troubleshooting. This is wonderful and more people just getting into electronics should watch and it’s what electronics is really all about.
Thanks for including your mistakes. I learned a lot from watching how you used troubleshooting to find and fix the problem (reversed diodes).
very helpful tutorial. a few pointers to help. the diodes wil have a voltage drop and the supply voltage is often better slightly higher than requird to account for this and effects of the regulator. heat may cause problems e.g the capacitor is very close to the transformer which can dry the electrolyte causing failure and the regulator generates heat as well. the regulator also requires additional components as required by the datasheet to correctly operate which would help with the voltage drop. lastly your idea of using the two end taps of the transformer is viable but would require the regulator needing a heatsink. for those wondering why the regulator converts the excess voltage to heat. thank you for sharing your method
Dude, funny how I saw that problem when you first had the drawing out there, so I was not surprised that it did now work, in fact I found myself shouting at the screen "THE DIODE"S" but strange as it may seem, you could not hear me since I was viewing this some 5 years after the fact, and, of course only the government monitors what I say in my living room through the microphone on my laptop, television, cell phone and other microphones that many do not even think exist. Great learning experience even for we ancient's who still get a thrill when that LED comes to life; telling us that our efforts are indeed paying off!
Was hoping that you would find those reverse biased diodes, well done. It's honest of you to show your mistakes.
The methodology you used for designing the board is quite handy.
You are wonderful. As you said the most important thing is to get the basic theory and to have successful small project will take to the complex project or troubleshooting.
Excellent video, good advice to have a break/cup of tea then come back to the project fresh, lots of useful info and lot of learning happening. The learning happens when a project doesn't work and you have to find out why.
Well done. Thanks for the demonstration! I agree with others, that leaving the mistakes in is a great idea. Effective in teaching, in my opinion.
So, early on, I kept thinking I must be mis-reading something, because I could swear two of the diodes seem backwards. Sure enough... the beauty of pencil!!
Great tutorial! I like your easy-going style and that you kept the "oops" w/ the diodes in there. I learned a lot. Thanks!
I love your videos. You're a great teacher and easy to understand.
Great how you show the mistakes so that I may learn better...... to many phonies showing final cut and copy of their diy vids .... thanks again!
The one most important & most valuable thing that we are lacking as beginners is experience, and there's only one way to get that!
actually making mistakes gives you the opportunity to troubleshoot your design and/or circuit so dont be afraid to make mistakes
Excellent video. Thank you for sharing this kind of thing with us beginners. It's very helpful to see real-world mistakes and fixes.
This is a great learning exercise, but practically speaking there are tons of used power supplies in garage sales. I picked up one for a laptop rated 9 volts for 3 amps for 3 dollars. I opened it up and changed the output to a dc barrel jack to use for a a universal plug.
great video for a beginner on breadboard to perfboard. glad you left the error in...seeing how to troubleshoot is dead interesting.
you got it! when i first started watching i noticed the diodes and was hoping it wouldn't cause anything to blow up. you have multiple voltage drop locations, the diodes have a forward voltage drop and the regulator also has a minimum working voltage, so it cant regulate 12 volts from exactly 12. it needs more then this to regulate at 12. i am currently making a +12 -12 supply now, so going through all this myself at the moment.
We all learn from our mistakes. And we learn from others when they are admitted, well done.
Some observations:
I would have kept the regulator standing upright and put a heat sink on it for good measure.
Also if the cap is laying down put some hot glue on the edges to keep it firm.
Lastly. when you close the top and the LED goes in the panel mount holder, it will most likely click into the holder and without any slack in the leads, when you remove the cover you are going to rip it off the board.
you are a legend of all time.
THANKS
Thanks for the clear explanation. You really talked me into building one myself!!
GUD job Sir.....i love your style of working.....
Mohsin u My pleasure, thanks for the post.
hello mohsin...do u like electronics...?
mjlorton
Great Video Martin !!! I use graph paper to plot my circuit
thank you so much I have always wanted to build my own power supply and now I can.. I really enjoyed your video thank you.
It just happens to be the one I had at hand...size might have been an issue...and I was happy with the amount of ripple I'd end up with using it.
Very "good".
Truly, I learned a lot...
Good video . I like the way you lay it out on paper . I'll do it your way next, may be my things will work now.
I notice a simple mistake, check the datasheet, it should have 10uF capacitor on the output of 7812, without it that why the voltage drop.
My pleasure, thanks for the feedback.
When you were saying to make sure the capacitor is the right way around otherwise things can go bad, right as you plugged the capacitor into the board my computer power supply died. Too spooky for me.
look at each wire with a temperature meter to see what one is resisting the most . don't burn yourself . have a nice trip buddy !
The voltage in the US is not 110 Volts, by the way, it is 120 Volts. Many people say 110 and 220, but we use 120 and 240 Volts AC, for the most part, in residential applications. Some devices will work at 105, 110, 115, 125, 210, 220, 230, 250 Volts AC, etc. Yet, the supply voltage is 120 Volts, or 240 Volts, give or take a few Volts.
You get a .7voltage drop from each diode. So for each a/c cycle it goes through two diodes plus another voltage drop through your regulator. And then again through your led.
7812s do not need 14.5V to work. They do if you want to maintain regulation at 1A output, but they will regulate for low currents with significantly less dropout than 2.5V. They don't just go dead and output nothing if you don't feed them a high enough voltage, either.
Just about to convert it for use here in the US...will see if i can look into that LED at the same time...
Ta, Martin.
You can try using a razor instead of drill to cut the tracks. I'm able to cut and peel my protoboards. It is so cheap and easy to get boards custom made (like the ones I sent you) that it is really worth the effort to learn how to use Eagle so you can just have your own board designs made. Come visit me in Atlanta anytime. Tot ziens.
Your diode drop is a total of 2.4 volts. Subtract that from 16 volts you get 13.6 volts. Drop out voltage of a 7812 is 2 volts. 13.6 a 2 is 11.6 volts. Add a little variance and you get your 11.5 out in real world.
WOW. You are going to have a ton of 220 vac powered equipment. Sounds like a video subject. How to power all your 220 v hardware on a 120 vac mains network.
Welcome to the USA.
JP
The half volt loss isnt a power loss, but is from your meter reading RMS and the output having a ripple, connect a suitable output capicitor (~.1microF) on your 7812 and it will get closer to 12V.
The fuse is only there to protect the circuit against shorts. So you would need a >200ma fuse for your project if you want to draw more current.
A lot of good advices from your experience. Thanks a lot!
NIce job. Cant wait to make one myself. THUMBS UP DUDE.
great great leason happy guy. thanks. you make it much easier for me to understand
There is a mistake in bridge rectifier which can destroy your circuitry . The dropout voltage could be the LED in the output Thank u for your videos sir
I would also suggest to increase the spacing between the transformer and the cap - the case looks sealed so the transformer might heat up which has an negative effect on the caps lifespan.
nice work man, you help me a lot to understand things better. thank you :)
Good job, but I think you should be a little more cautious with the mains connections (eg encasing the metal transformer core with plastic to prevent arcing between AC and DC sides).
doesn't the voltage regulator generate a lot of heat? how did you address that?
The heat in it will be related to the current through it. This power supply is only 100mA at 12V. The voltage out of the bridge rectifier is 16V, so the maximum power dissipated in it is 0.4W which shouldn't require a heatsink. If the transformer is wired up for higher output voltage as was suggested at one point in the video, it will get much hotter, but the dropout across the regulator is not the cause of the problem, so that would be pointless anyway.
The output voltage is simply what that particular 7812 produces. It is actually in spec (if right at the limit). These are not precision laser trimmed voltage references, they're jellybean regulators.
Try Multisim to design your schematics, and then try Ultiboard to design your PCB.
"Thank You", thank you very much.
That was very "good"...
A fixed dropout voltage is a common misconception. In this application, the dropout voltage of a 7812 is much lower than 2.5V. At ambient room temperature it should be
He gets 12 V AC rms (+5-10% on low loads) on the secondary of the transformer, NOT DC voltage.
The AC voltage is rectified by those 4 diodes into DC voltage so 12v AC RMS becomes 1.41 x 12v = ~ 16.9v DC.
Then you have the drop across two out of the four diodes of about 0.8-1.4v depending on what diodes are used, so 16.9v becomes 15.5-16v DC in front of the 3300uF 25v capacitor. Obviously a 16v cap. would be unsuitable.
The 15.5-16v is PEAK, it may go below 14v due to low capacitance at input.
Thanks for your very informative clip great advice for beginners like me.
the led is taken the extra half a volt, try disconnecting the led and measure the voltage output.
just found this, nice vid, very informative and great fun, thanks!
The 3300uF capacitor adds additional dc smoothing to the design and should not be a problem. However, I have come across the odd regulator in my designs that was not within specification, it was solved by changing the regulator to get the desired output. The other option is to purchase a 12 volt precision regulator that will operate at it's specified output, especially when you are working on critical projects and you want the numbers to be spot on. But for most practical applications 1/2 voltage drop will have no impact on circuit operation.
Hi, your awesome ,
may i ask how to boost the 1000mA to 2000mA, for the ipad , it wont charge fast or good only if using its charger the big 2 part charger its output 5v 2100mA.
hope you can advise me.
thanks again
Just add a 100nF - 10uF capacitor at the output of the 7812, should improve ripple rejection and stability. Also,the 78XX family isn't precisely famous for it's accuracy.
Good vid though.
hi mjlorton it was a nice video but can you please share any video of AC/DC/AC converters which will really beneficial. thanking you
The transformer provides sufficient voltage headroom for the rectifier and regulator drops. However, the fuses must be moved and properly insulated.
To add to my prior comment, he had 16.5 volts across the capacitor, more than enough to properly drive the regulator. I have built enough power supplies to know that the capacitor will actually increase voltage by 4 to 5 volts which it did in this case, so there should be no issue. These regulators are designed to operate at maximum input of 30 volts to maintain stability.
what is the voltage drop across your LED? I suspect that is where you are loosing your .5 Volt plus you are not considering the error of loss over the circuit.
That regulator doesn't need a heat sink though for only 40ma. But that transformer is much larger than that, so taking 500ma of current from that will result in a bbq in there.
Very nice video and some excellent advice.
Great video.
check the gauge of the wires and length to recover the drop
In your previous video you calculated that you need >4200f cap, in this one you are now using a ~3300 f cap. Is there a reason behind this?
awesome & inspiring! thank you for sharing.
Well done! thank you
I wish you great success always greetings to you
i use Circuit Wizard great easy to use pcb program make and test circuits before coverting to print artwork or gerber
yes for simple/middle of the road boards its a great tool /dip trace is more for the pro`s
Very nice demonstration and video. One question: In the schematic I noticed a bias resistor and diode across the output - did I miss them on the circuit board someplace? And specifically, what is the purpose of those two components; do they help to maintain the output voltage, keeping it from exceeding the 12 volts you wanted? Thanks again!
2mm clearance from main to skin w/o the pad on the back.
Hi how do you know what capacitors to use?? in the supply??
Thanks for making this video. I learned a lot as I need to make a power supply of my own. On the 0.5 voltage drop, I was wondering if the regulator you use specifies 2 volts higher than the output to get the correct voltage? As what I've studied suggest as much. I was also curious why you put the mains fuse on the outside of the transformer instead of the inside. I've seen some (not all) circuits that put the fuse on the inside.
build in eagle cad , measure , then select box
First off, awesome video. I was wondering if you could tell me how much current this design could handle? How many amps is this capable of producing and is there a way to alter the output voltage to say 13.8 or so?
Does the regulator need a heat sink?
You will get a forward voltage drop through the diodes
transformer wires which two wires should use at ouput
How do you ensure that your device doesn't overdraw current (other than the fuses of course)? Are you just doing that to protect your circuit in the event of a short?
hehe a little late, (2-3 years) but hay.. need to know info.
but i'm sure you "need" by law a circuit switch on the mains part of the project, so it's visible and possible for all to turn it off.
atleast in EU.. ;)
Hi Martin, I want to make a laptop adapter similar to yours but my output volts should be 19V to feed my acer aspire 5315 laptop. Now for buying a transformer, what specification of transformer do I need to say to the shopkeeper?
120VAC is nominal USA mains voltage, not 110 like you said.
Did you ever figure out what caused the 0.5V voltage drop? My guess are the diodes in the bridge rectifier...
WhoWantsToKnow81 i dont think diodes might be a problem, as he is able to get 16.5 across capacitor output.I think the drop is somewhere in IC only,but according to datasheet specs,it should give 12V output if input is 16.5v
WhoWantsToKnow81 I had a look at it a month ago and found the problem....I'll add an annotation to the video as well. The LM7812 was faulty! I tested it and it was not providing the correct regulated 12 volt output. I replaced it with a new one and the problem was solved.
mjlorton
Cool, thanks for letting us know!
WhoWantsToKnow81 Yes the diodes do cause a voltage drop...but I think there are diodes that have a very low voltage drop...
nice video but I don't like to mount the fuses on the transformer legs!
Creative video, thanks :)
Hi. Need some help.
I got in my power suply two toroidal transformers 220/11.5 100A =200A,
Four 50A bridge rectifires.
And i don't know what el.capacytor to use!?
How to calculate what kind to use?
Tnx
Thanks a lot sir....i think it will help me much... :-)
thanks you sir, God bless!
Aha yes... Boarding software... I'm currently using Fritzing. Free software for Mac and Window. Its made by University of Applied Sciences Potsdam. It provides drawing Breadboards, Schema's and PCB. Maybe it's something you'll find easy to use. But yeah, it seems paper and pensil are faster cause the mind is more focussed on the job rather than on how the software works. Specialy at first.
Is it not possible for us to mount the transformer on to the veroboard as we do it on PCB?
nice video!
Good stuff. Thanks.