Problem with proceeding circuit on a power suply. Can help?

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Problem with proceeding circuit on a power suply. Can help?

Postby xandaz » Fri Sep 08, 2017 2:51 pm

I made a power suplly that powers both a la7809 and one LM317. There is a circuit poceeding the carpacitor with two dual voltage comparators that are supplied from here. Four 22k timmers define a voltage condition. A sample taken from the LM317 output. All the trimmers are in parallel, samples even. The volatges programmed are like 4.7, 9.8,12.1, 14.5 or whatever is wished. So the timmers are programmed but on the second comparator the voltage is interlaced somehow the reacted theres a lump kind thing. a little jump.
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Re: Problem with proceeding circuit on a power suply. Can he

Postby Valen » Fri Sep 08, 2017 3:22 pm

Maybe it's because I just watched an episode of Startrek DS9, but this read like nothing but techno-bable. What on earth do you mean?
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Re: Problem with proceeding circuit on a power suply. Can he

Postby markaren1 » Fri Sep 08, 2017 5:48 pm

A half-reasonable schematic would be useful, please post one.
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Re: Problem with proceeding circuit on a power suply. Can he

Postby xandaz » Sun Sep 10, 2017 1:23 am

fa4.png
fa4_shot.png
mask

Sorry... i think i need a little grammar retorics. I thought a had attached. it all works except when relating to power. its just that second comparator and its not the chip. I'm just starting ok?
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Re: Problem with proceeding circuit on a power suply. Can he

Postby xandaz » Sun Sep 10, 2017 1:24 am

i notice that there are some ground symbols missing but they're on the mask
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Re: Problem with proceeding circuit on a power suply. Can he

Postby xandaz » Sun Sep 10, 2017 3:53 am

the mask isnt up to date either. tx
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Re: Problem with proceeding circuit on a power suply. Can he

Postby n1ist » Tue Sep 12, 2017 8:35 am

There's a pour on the PCB that isn't connected to anything. As such, it is broken into many little pieces. You need to tell the PCB layout software that it is tied to ground.

There is also a major safety issue. You need to keep the ground pour away from the transformer primary side pins and traces. 6.5mm is a good distance.

As for the schematic, it doesn't match the board, so it doesn't help much. It is unfinished. Finish it first before starting layout. I would also draw the bargraph circuit separately from the regulator and use named nets or power symbols to interconnect them. Ground and power symbols are free; using them instead of drawing in a connection between every grounded or power pin will reduce the clutter.
BTW, you are missing bypass caps on the comparators and the 7809. The latter is likely to oscillate without them.

/mike
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Re: Problem with proceeding circuit on a power suply. Can he

Postby xandaz » Thu Sep 14, 2017 5:56 am

thanks in advance. I didn't know that comparators needed those bypass capacitors. I'm not sure of much when it relates to electronics. Those capacitors go in the comparators supply? Could that lump be about that? I also didnt know that ground should be away from the side pins... It works prolly just as little as my sapience.
tx mike.
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Re: Problem with proceeding circuit on a power suply. Can he

Postby xandaz » Thu Sep 14, 2017 6:42 am

oh... i see now. I thought that the input capacitor was a ripple capacitor. What capacitance for 9v/0,5A? i see values rounding 100nF in input and 22nf on the output. Is there a known rule or formula for that? doesn't seem to be in the datasheet.
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Re: Problem with proceeding circuit on a power suply. Can he

Postby xandaz » Thu Sep 14, 2017 6:48 am

also.... yeah that copper mask doesn't match the circuit. It has a zener from where i drain the power to the comparators and also some gaps to connect switches. It's an object of study.
tx
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