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Re: SMD Led

 

Hello Kevin,

Friday, May 24, 2019

You should have done the holes and cut outs BEFORE soldering, then
you can clamp pieces of square or rectangular section steel along the
edge you will file and use the steel section as a "stop" to get
perfectly straight and square edges in exactly the right places. I am
spoilt as I am in the race engineering game so just use the
Bridgeport universal miller. Depending on what bits of steel you can
find you *MAY* still be able to use this method on something already
assembled.


Best regards,
Chris mailto:chris@...


KBvGI> Thank you Harvey that sends me off in right direction for future boards ect.
Re: How do you make nice clean cutouts in pc board material?

 

Here is a photo that I use.?


On Sat, 22 Jun 2019, 12:15 pm MVS Sarma via Groups.Io, <mvssarma=[email protected]> wrote:
Yes.
We get a scapping tool called laminate cutter . Very cheap as in India we pay less than 1$
Toppcb of enclosure is to be separated . Measure and mark with marker pen on either side. Start using the scrapping tool with a straight edge support. We use steel ruleer.
I shall post a photo how this tool looks.?
?I eas able to make rectangular cut foe lcd display window.

On Sat, 22 Jun 2019, 12:10 pm Dave, <dave@...> wrote:
On 6/21/2019 10:00 PM, Jim Pruitt wrote:
I need to cut out an area of the top of a pc board enclosure (enclosure made using double sided pc board material).? The cutout is for a 16x2 LCD display.? Can someone tell me how to do that and keep the lines straight?

I used a coping saw to do the first one but needless to say,? the cutout did not stay straight and with filing I ended up with part of the cutout too big.? I tried just using a razor knife and cutting the lines but could not get the board to break on those lines.

I have in the past been told to use a Dremel tool but I have not found a bit for the Dremel and have not seen the little 1" diameter saw blades for a while,? not that I would trust one to go straight for me anyway.

There has to be a reliable and neat way to make these cuts.? Does anyone know how to do this?

Thank you.

Jim

20190622_121747.jpg

Re: How do you make nice clean cutouts in pc board material?

 

¿ªÔÆÌåÓý

Jim:
? I just got some front panels made of PCB from JLCPCB.? They had a cutout for a 16 X 2 LCD, several holes for push buttons and a coupe of larger holes for a tuning control and a rotary selector switch.? Cost with shipping was less than $3 each for 10.? Lettering, holes, and cutouts are perfect.? You have a choice of colors for both the solder mask and sillk screen. ? I got red pcbs with white silkscreen.? I used KICAD to design the boards.? Delivery was under a week from placing the order.

Dave - WB6DHW

On 6/21/2019 10:00 PM, Jim Pruitt wrote:

I need to cut out an area of the top of a pc board enclosure (enclosure made using double sided pc board material).? The cutout is for a 16x2 LCD display.? Can someone tell me how to do that and keep the lines straight?

I used a coping saw to do the first one but needless to say,? the cutout did not stay straight and with filing I ended up with part of the cutout too big.? I tried just using a razor knife and cutting the lines but could not get the board to break on those lines.

I have in the past been told to use a Dremel tool but I have not found a bit for the Dremel and have not seen the little 1" diameter saw blades for a while,? not that I would trust one to go straight for me anyway.

There has to be a reliable and neat way to make these cuts.? Does anyone know how to do this?

Thank you.

Jim

Re: How do you make nice clean cutouts in pc board material?

 

Yes.
We get a scapping tool called laminate cutter . Very cheap as in India we pay less than 1$
Toppcb of enclosure is to be separated . Measure and mark with marker pen on either side. Start using the scrapping tool with a straight edge support. We use steel ruleer.
I shall post a photo how this tool looks.?
?I eas able to make rectangular cut foe lcd display window.

On Sat, 22 Jun 2019, 12:10 pm Dave, <dave@...> wrote:
On 6/21/2019 10:00 PM, Jim Pruitt wrote:
I need to cut out an area of the top of a pc board enclosure (enclosure made using double sided pc board material).? The cutout is for a 16x2 LCD display.? Can someone tell me how to do that and keep the lines straight?

I used a coping saw to do the first one but needless to say,? the cutout did not stay straight and with filing I ended up with part of the cutout too big.? I tried just using a razor knife and cutting the lines but could not get the board to break on those lines.

I have in the past been told to use a Dremel tool but I have not found a bit for the Dremel and have not seen the little 1" diameter saw blades for a while,? not that I would trust one to go straight for me anyway.

There has to be a reliable and neat way to make these cuts.? Does anyone know how to do this?

Thank you.

Jim

Re: How do you make nice clean cutouts in pc board material?

 

¿ªÔÆÌåÓý

On 6/21/2019 10:00 PM, Jim Pruitt wrote:

I need to cut out an area of the top of a pc board enclosure (enclosure made using double sided pc board material).? The cutout is for a 16x2 LCD display.? Can someone tell me how to do that and keep the lines straight?

I used a coping saw to do the first one but needless to say,? the cutout did not stay straight and with filing I ended up with part of the cutout too big.? I tried just using a razor knife and cutting the lines but could not get the board to break on those lines.

I have in the past been told to use a Dremel tool but I have not found a bit for the Dremel and have not seen the little 1" diameter saw blades for a while,? not that I would trust one to go straight for me anyway.

There has to be a reliable and neat way to make these cuts.? Does anyone know how to do this?

Thank you.

Jim

How do you make nice clean cutouts in pc board material?

 

¿ªÔÆÌåÓý

I need to cut out an area of the top of a pc board enclosure (enclosure made using double sided pc board material).? The cutout is for a 16x2 LCD display.? Can someone tell me how to do that and keep the lines straight?

I used a coping saw to do the first one but needless to say,? the cutout did not stay straight and with filing I ended up with part of the cutout too big.? I tried just using a razor knife and cutting the lines but could not get the board to break on those lines.

I have in the past been told to use a Dremel tool but I have not found a bit for the Dremel and have not seen the little 1" diameter saw blades for a while,? not that I would trust one to go straight for me anyway.

There has to be a reliable and neat way to make these cuts.? Does anyone know how to do this?

Thank you.

Jim

Re: SMD Led

 

Thank you Harvey that sends me off in right direction for future boards ect.
Re: SMD Led

 

Thank you for your ideas. I have a surface mount tester and special probes coming from Bangood.com but 9 volt and usual
5 mm resistor told me two different ends of super small Led. How to get specs on surface mount China parts with no markings
for my Eagle program and Apache lam aspect of this? Any ideas as to where to figure this out?
Re: SMD Led

 

¿ªÔÆÌåÓý

On the bottom of the led look for a bar and a square.? The square is pointing to the cathode.? On the top of the LED, there may or may not be a green marking under the transparent plastic covering the chip.? That should indicate the cathode.

On the physical picture (parts layer) look for the picture of the LED to to have (if you're lucky) the same bar and dot, or perhaps a triangle of 3 dots with the center dot pointing to the cathode.? That varies by PCB program, though.

Do not depend on the body of the chip to be the cathode and the wire to be the anode.? That can vary.

If needed, you can modify one of the little LED testers with a pair of banana jacks, which would connect to one of the measuring tweezers (just the wires, no electronics).? That would allow you to select various currents (5 ma is fine), as well as test other LEDS.

If you're lucky, there might be one that is adapted to surface mount parts.

The common LCR tweezer style testers may not have enough voltage for blue and white LEDS.

Harvey



On 5/24/2019 4:00 PM, Lee Studley wrote:

K is usually cathode(?Greek kathodos( "descent"?) )
I think the dot in the "led_sch_top.jpg"" and the green squares "LED Bottom View.jpg" pictures are on the cathode side.
But the picture Led Top View.jpg is ambiguous

Re: SMD Led

 

"Kevin Byrne via Groups.Io" <kbyrne10@...> writes:
In the clipboard file are three pics of a SMD led project. Question is
the green triangle pointing at K=Anode so as to buy this led in future
from orient? I am new to surface mount and need this clarified.
I've found that the leads on my multimeter happen to have the correct
polarity when in "diode test" mode. So I put it in that mode, and touch
the pads on the SMT LED. If the LED lights up (er, doesn't work for
blue LEDs - use the battery+resistor trick) then I have the red lead on
the + pad and the black lead on the - pad.
Re: SMD Led

 

9 volt battery with resistor on positive red wire led lights up LED with black wire to green squares side. Triangle is bottom side down to board. Pictures are?
wrong. Thanks to your green squares comment. That jpg should read Led Top View. I have it figured out now. Thank you Kevin
Re: SMD Led

 

K is usually cathode(?Greek kathodos( "descent"?) )
I think the dot in the "led_sch_top.jpg"" and the green squares "LED Bottom View.jpg" pictures are on the cathode side.
But the picture Led Top View.jpg is ambiguous
SMD Led

 

In the clipboard file are three pics of a SMD led project. Question is the green triangle pointing at K=Anode so as to buy this led in future from orient?
I am new to surface mount and need this clarified.
Re: New PCB board/Yellow Wire

 

Thank you for all your replies. Best Kevin
Re: New PCB board/Yellow Wire

 

Yellow Wire modification to boards, especially very complex multi-layer boards is not uncommon in the military and space fabrication. If there was a design error in the brass board, subtle change going from brass board to flight boards, parts changes, failure in environmental, vibration, RF leakage or sensitivity, functional testing, and of course Customer Requirements changes it was customary to use the already tested and approved yellow wire changes approach. That allowed incremental re-testing instead brand new board design and layout (new traces probably don't quite fit the current design), fabricate another short run (separate test from deliverable), and began testing again from the ground up.

Of course for contracts that would have more than just one or two deliverable you would eventually do the redesign and retesting to get a production board with the fewest possible re-work spots. But yes Yellow Wire changes, including 'staking' (bonding the wires i place), cutting pins flush with the board and then bending them upright for yellow wires to disconnect from internal traces, dead bugs (chips glued back to back onto existing? chips with pins sticking out) is a well known and accepted practice.


--
"Creativity is intelligence having fun." ¡ª Albert Einstein
Re: New PCB board

 

I use them to fix mistakes when I don't want to wait for a new board.? If it's the first revision, there's likely to be a design error in there in addition to the need for the jumper, or maybe I just come up with a better idea.

I prefer boards without such jumpers.? If I have to break a trace, then I'm likely to note that on a schematic and fix any boards that have been made with that error.

Harvey

On 5/19/2019 4:26 PM, Mark Pilant wrote:
These wires are very often used to implement ECOs/FCOs (Engineering/Field
Change Orders).? I don't think it is as common now, but it used to be the
case where it was fairly costly to spin a new board, and adding some wires,
cutting traces, etc. in the field (now mostly at the manufacturer) was much
less expensive.

- Mark
Re: New PCB board

 

These wires are very often used to implement ECOs/FCOs (Engineering/Field
Change Orders). I don't think it is as common now, but it used to be the
case where it was fairly costly to spin a new board, and adding some wires,
cutting traces, etc. in the field (now mostly at the manufacturer) was much
less expensive.

- Mark
Re: New PCB board

 

I stole from a websearch. was surprised there weren't more good examples. It's really an art-form in is own right.
Re: New PCB board

 

Nice photo by the way. As long as it is connected good and transistor is heat sink protected while soldering all should be well I gather as a newbi home hobbiest only. No formal training.
Re: New PCB board

 

Yup, I have seen some ¡°big brand¡± names with ¡°green wire¡±
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