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Jonathan
04-01-2017, 08:01 PM
this is my pcb with rectifier and 2 capacitors.
20217


The tracks you have for the DC positive are wide enough for maybe 3 amps ... certainly nowhere near 14A. The current wont be near to 14A, but still those tracks are optimistically sized.

You could do something similar to mine (http://www.mycncuk.com/threads/10475-PSU-Rectifier-Capacitor-smoothing-board-for-toroidal-transformer?p=86757#post86757) - happy to share the dxf for the PCB.

Doddy
04-01-2017, 08:02 PM
I would like to start new thread.

This is going to be kind of guide how to chose correct voltage and power of Toroidal Transformers to suits our need.
Hope this will be useful for custom build linear power supply.


This is wrong on so many levels.

Please don't push 14A through that PCB.

JAZZCNC
04-01-2017, 08:05 PM
This is wrong on so many levels.

Please don't push 14A through that PCB.

Could not agree more this thread is dangerous in the wrong hands.!! . . . . Blind leading blind comes to mind.!:hopelessness::disillusionment::thumbdown:

Jonathan
04-01-2017, 08:10 PM
10 amps through a similarly sized track:

20223
20225
20224

So don't forget the volt dropped across the PCB track

Sorry, I was bored...

Tom J
04-01-2017, 08:15 PM
The tracks you have for the DC positive are wide enough for maybe 3 amps ... certainly nowhere near 14A. The current wont be near to 14A, but still those tracks are optimistically sized.

You could do something similar to mine - happy to share the dxf for the PCB.

Jonathan this pcb is for 3x3A steppers which takes no more than 7A from my calculation, but real test by clamp meter revealed that was no more than 0.86A therefore even perforated prototype board worked fine (but should not)
I really should't show that - 1st pcb cut (on the left was Eagle pcb, on the right my revised version which still is not wide enough)

For my 70VDC 7A motors I use the same layout but wider path on pcb.
Just checked current-carring capacity and 1mm2 will handle 11A.
For 16.5A i need exactly 1.5mm2 conductor, so 1mm pcb has 0.035mm of copper.
Path width=1.5/0.035=42.86mm - my entire PCB is 50mm wide, according to this calculation we both wrong:shame:

I like that drain resistor - how many ohms?

Where do you buy components if you don't mind me to ask - your price are better than mine:(

Tom J
04-01-2017, 08:20 PM
Could not agree more this thread is dangerous in the wrong hands.!! . . . . Blind leading blind comes to mind.!:hopelessness::disillusionment::thumbdown:

so delete it, It was about transformer now is about pcb - my fault :beaten:

Robin Hewitt
04-01-2017, 08:25 PM
Could not agree more this thread is dangerous in the wrong hands.!! . . . . Blind leading blind comes to mind.!:hopelessness::disillusionment::thumbdown:

Poorly rectified AC going in to a inductive load with a chopper circuit controlling the current.

What could possibly go wrong? :cool:

JAZZCNC
05-01-2017, 12:28 AM
so delete it, It was about transformer now is about pcb - my fault :beaten:

Deleting got nothing to do with me but if could believe me I would.!. . . . This thread is dangerous in the wrong hands and trust me there are many silent watchers out there who will try without asking or researching until it's too late..!!

Tom J
05-01-2017, 12:29 AM
Deleting got nothing to do with me but if could believe me I would.!. . . . This thread is dangerous in the wrong hands and trust me there are many silent watchers out there who will try without asking or researching until it's too late..!!

that is why I started, just to clarify things with help of experts, CNC is dangerous too, how many of you using safety doors, light guard or any other safety features?
Is there any way to delete it, how to do it? Do not want to cause any more trouble.

Lee Roberts
05-01-2017, 03:43 PM
Hi guys,

After receiving a couple of reports on the original thread (it needing attention), I decided to split the discussion, allowing it to continue regarding the selection process, with a new discussion for the PCB side of things, as both topics deserve the proper observations.

You can find the links to each discussion below, thank you to everyone involved, feel free to continue both discussions:

Link 1: Help please with toroidal transformers selection (http://www.mycncuk.com/threads/10500-help-please-with-toroidal-transformers-selection)

Link 2: Please don-t push 14A through that PCB !!! (http://www.mycncuk.com/threads/10508-Please-don-t-push-14A-through-that-PCB-%21%21%21)

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