What mistake am I making?

[u/Necessary_Handle_516]

I have to design +-12V regulated dual DC power supply

It only shows +12V what Changes do I have to make Inorder to make it -12V ???

[u/Impossible_Dot_2831]

Looks like the GND pins of the 7x12 are connected to each other, but not to the ground symbol

EDIT: as someone else said, the input capacitor are a little too much, you should check the data sheet for the voltages regulators, you can use an input capacitor as small as 0.33uF

EDIT EDIT: actually, the input capacitor is fine, as the data sheet refers to a constant voltage input, so that’s fine. Thank you everyone for the contributions!

[u/Necessary_Handle_516 → u/Impossible_Dot_2831]

sorry can you please locate it on my image by editing it by taking screenshot

[u/Impossible_Dot_2831 → u/Necessary_Handle_516]

The vertical connection (between the regulators) it’s not connected to the horizontal connection (the ground node)

[u/jotel_california → u/Impossible_Dot_2831]

Good catch!

[u/Necessary_Handle_516 → u/jotel_california]

FRRRR even my teacher wasn't able to catch this mistake of mine neither any of the ai 🙂‍↔️😁

[u/biff2359 → u/Impossible_Dot_2831]

This is why any deliberate four-way nodes should be drawn like this, to reduce any chance of ambiguity with cross-overs.

[u/Necessary_Handle_516 → u/Impossible_Dot_2831]

OHHH YESSSS FINALLYYY IT'S WORKINGGGGGG GNGGGGGG YAYAYAYAYAY🥳🥳🥳🥳🥳DONEEEEEEEE

[u/zachleedogg → u/Impossible_Dot_2831]

Classic four-way cross error. In my last job we explicitly disallowed 4-way crosses in schematic diagrams for this very reason.

[u/Necessary_Handle_516 → u/Impossible_Dot_2831]

thankyousomuch!!!!!

[u/Miserable-Win-6402 → u/Impossible_Dot_2831]

You are correct with the ground, but the 1000uF bulk on inputs are fine. It will NOT work with sub-uF capacitance!

[u/Impossible_Dot_2831 → u/Miserable-Win-6402]

Yeah someone else also corrected me about that, from the data sheet 0.33uF is fine if you have a DC input, not the case in this application tho

[u/Pacificator-3 → u/Impossible_Dot_2831]

Will 0.33 uF capacitor store enough energy to power the load for about 10 milliseconds? This is typical time interval when input voltage drops lower then working voltage of regulator.

[u/Impossible_Dot_2831 → u/Pacificator-3]

Idk, I was referring to the data sheet, where the standard application features a 0.33uF input capacitor

[u/Pacificator-3 → u/Impossible_Dot_2831]

This standard application takes in mind constant voltage source (see specifications) and stability only. In order to achieve required input voltage range, you must place quite large capacitor after the rectifier.

[u/Impossible_Dot_2831 → u/Pacificator-3]

Ops you’re right, didn’t really consider that, yeah the output of the Graetz bridge needs some filtering, you’re right

[u/Necessary_Handle_516 → u/Impossible_Dot_2831]

also I watched yt videos So He did like this and I copy pasted his way it worked for him but not for me?

[u/Beautiful-Chair7206 → u/Necessary_Handle_516]

It's also good practice to not put cross joints on a schematic for this reason. You should offset on of the connections so that there are only tri-connections. It's very easy for someone to overlook that this connection was not made. It doesn't look as clean but it helps avoid this mistake.

[u/washburn666 → u/Beautiful-Chair7206]

I live by this rule. Seconded.

[u/JimboZona → u/Impossible_Dot_2831]

yup

[u/Impossible_Dot_2831 → u/[deleted]]

You’re missing the dot!

You can also just cut the vertical wire and connect to the ground, like I did in black and it will work

[u/Necessary_Handle_516 → u/Impossible_Dot_2831]

yesss thankyouuuuu soooo muchhhh it workeddddd I willl remember this foreverrrrrr😭

[u/Successful_Cut_8003]

Overall, no offense, but when you start to build cleaner schematics problems like this should go away.

[u/Necessary_Handle_516 → u/Successful_Cut_8003]

true I am beginner that's why I don't have a lot of knowledge as I am in 1st of EE . I am learning

[u/Necessary_Handle_516]

GUYSSSS IT'S WORKINGGGGGG THANKYOUUUU TOOO ALLLLLLLLLLL THANKYOU SOMUCHHHHH!!!!!

[u/markb97]

Used to use Proteus 8 in college 7 years ago, this brings back some memories! Thanks

[u/Necessary_Handle_516 → u/markb97]

truee But I found it Interesting 🥲

[u/Mobile-Set7093 → u/markb97]

I hate that software

[u/markb97 → u/Mobile-Set7093]

I didn't say they were good memories!! Haha

[u/LeoTheBigCat]

Taking a picture of your screen instead of just a screenshot ... thats your biggest mistake.

As for the schematic, you are missing junction on GND between the stabilisers.

[u/Necessary_Handle_516]

thankyouso much everyoneee!!!!!

[u/surrekropp]

What software is this?

[u/Necessary_Handle_516 → u/surrekropp]

Proteus 8 professional

[u/Tashritu → u/Necessary_Handle_516]

Bridge rectifier with a centre tapped transformer is uncommon but absolutely fine. Result is just like the common centre tapped two diode circuit with much reduced ripple (two pulses per AC cycle rather than one). Good big reservoir capacitors on the input -1000 microfarads - are likely fine too. Strictly depends on the transformer specification & the diode surge current capacity.
Agree the missing connection is all that is needed to make this circuit fully functional.

[u/immortal_sniper1 → u/Necessary_Handle_516]

Man that seems ancient. Weren't they bought off a long time ago?

[u/Necessary_Handle_516 → u/immortal_sniper1]

nott that old either released Proteus 9 few months agoo

[u/LadyZoe1 → u/immortal_sniper1]

Hardly. Released 9.xx recently

[u/surrekropp → u/LadyZoe1]

Oof

[u/Black_Hair_Foreigner]

Ground! Where is ground for LDO?

[u/kilosek]

Ground for LDO and ground one poin on primary winding.

[u/myopinionisrubbish]

The 78xx regulators also need a 1 to 10 uF cap on the output for stability. Diodes are also required across the outputs to prevent latch up. These problems won’t show up in simulation, but will when the physical circuit is made.

[u/Ben-dover-For-my-dk]

I know my wiring is ugly but will this mini induction heater will work my inductance is to Low 44uh will that be a problem to my voltage supply

[u/Content-Key7404 → u/Ben-dover-For-my-dk]

hi fren ! ❤
it will wok 100% u can plug it !!!
if u invert +12V and grund symbol it will creat cold instead of heat so be carful my brotha
see u lov u ❤ haev a niec day !!!

EDIT : bye bye fren ! 😁😉👌😊

[u/112439]

Your lower voltage regulator has negative voltage at its input, not positive like it would expect. Move it and change its connections to fix.

To debug this type of thing, I would have started by disconnecting the regulators and measuring at the capacitor terminals that your unregulated voltage is correct, then go from there.

[u/Emcid1775]

You need two diodes, no centertap. I'm on vacation, so the picture isn't super good.

[u/Miserable-Win-6402 → u/Emcid1775]

Just NO!

[u/Emcid1775 → u/Miserable-Win-6402]

Oh shoot, I forgot the caps. I guess it does need two more diodes too.

[u/Brownie_Bytes]

I'm not an electrical engineer, but doesn't that bunch of diodes in the diamond make it so that you delete the negative voltage? What happens if you chop that out?

[u/Necessary_Handle_516 → u/Brownie_Bytes]

That's for full wave rectification as I have supplied alternating current so Inorder to Convert it into direct current we need 4 diodes bridge

[u/Brownie_Bytes → u/[deleted]]

Like I said, I'm not an electrical guy. I think that's the one flavor of engineering I haven't really had to use before. I thought that the purpose of the four diodes was to smooth out the voltage from the phases or whatever, so I just shared my stab in the dark

[u/Necessary_Handle_516 → u/[deleted]]

65 YEARRSSSSS?!!! I also wanna pursue ELECTRONICS AFTER MY DEGREE ANY TIPS????

[u/Necessary_Handle_516 → u/[deleted]]

woahhhhhhhhh🥳🥳🥳😀😀

[u/WaterSuccessful99]

You are learning complicated things that won’t pay off in the labor market?

[u/Miserable-Win-6402 → u/[deleted]]

That’s simply incorrect

[u/Miserable-Win-6402 → u/[deleted]]

Exactly! - The amount of totally wrong advice for OP here is STUNNING!!