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I need to help with a PCB layout on Eagle

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Maxxheadroom

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Hello all, I am trying to build a very basic scanning led circuit with a 555 and a 4017. I am trying to wrap my brain around Eagle PCB and honestly struggling. So I have a two part question, would anybody be willing to put together a PCB design for me based on this **broken link removed** while I figure out Eagle? Can anybody direct me to a very basic this is where you start tutorial for Eagle?

Thank you in advance
Maxx
 
Hi Maxxheadroom,

you won't have much fun with that circuit. With the LEDs connected via 1K resistors to the counter output they will be fairly dim. (The 4017 can source 10mA output current normally, whereas 20mA are required to drive an LED to full brightness).

The 1K resistors in series with the LEDs would supply a max current of 10.2mA for red LEDs with 1.8V forward voltage. This current reduces to 9.6mA for green LEDs with 2.4V forward voltage and to 8.5mA for blue LEDs with 3.5V forward voltage.

I suggest to use an NPN-transistor array (e.g. ULN2803) and two single NPN-transistors (e.g. BC547) for the nineth an tenth LED.

Then calculate the current limiting resistors for maximum current flow through each individual LED.

A PCB layout will be done in no time if everything is well planned.

I'm willing to help you out with a PCB design if you agree to use extra transistors to drive the LEDs.

Boncuk
 
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Have you tried this? It may be useful... Otherwise the Eagle website should be a good place to start.

indestructibles eagle pcb howto:
Create new project

I will check that out thank you very much Edman222

Hi Maxxheadroom,

you won't have much fun with that circuit. With the LEDs connected via 1K resistors to the counter output they will be fairly dim. (The 4017 can source 10mA output current normally, whereas 20mA are required to drive an LED to full brightness).

The 1K resistors in series with the LEDs would supply a max current of 10.2mA for red LEDs with 1.8V forward voltage. This current reduces to 9.6mA for green LEDs with 2.4V forward voltage and to 8.5mA for blue LEDs with 3.5V forward voltage.

I suggest to use an NPN-transistor array (e.g. ULN2803) and two single NPN-transistors (e.g. BC547) for the nineth an tenth LED.

Then calculate the current limiting resistors for maximum current flow through each individual LED.

A PCB layout will be done in no time if everything is well planned.

I'm willing to help you out with a PCB design if you agree to use extra transistors to drive the LEDs.

Boncuk

Boncuk,

I am very much new to all of this and any advice anybody can offer I would greatly appreciate. I have no problem using transistors to drive the leds, also I forgot to mention I will be using white LED's and the circuit will be powered with 12v. a big thanks to both of you guys for the quick response and generous help!
 
OK, that's cleared up so far.

What are the data of your white LEDs? (forward voltage and current)

Boncuk
 
Hi Maxxheadroom,

seems to have been a "misfire". I didn't receive any email from you.

I just have to know the LED diameter (3 or 5mm)?

Boncuk
 
Boncuk,

I really appreciate your stepping up and offering a hand, the LED's I am running are 5mm however they will not be mounted directly on the board. Also I need the 555 to be variable, I know I need to get a pot in there but not 100% sure where or which pot to run. I just got all my components in the mail and realized I goofed up when I ordered. My 555's are all SMD so I am going to have to reorder ARG. Anyway if this is to much of a pain please don't feel obligated, and if there is any other questions please let me know.

By the way your PM inbox is full.
 
Hi Maxheadroom,

the problem of adjustable speed has already been taken into account. You might place the pot off board and connect as shown in the schematic and PCB layout. If the speed is too high using a 10K pot replace it with a 25K pot.

LEDs used are 5mm.

Placing the LEDs off board shouldn't be a problem. Just use the vacant soldering pads of the onboard LEDs to connect the LEDs via cable.

Using an 8 wire ribbon cable connect two wires to +12V and the cathodes of the LEDs to the appropriate solder pads.

Don't mix up the sequence of LEDs since you won't get a "Knight rider" display in that case.

You might replace the 10KΩ resistor (R9) with a wire jump. The CD4017 can take full positive output pulses of the NE555 without damage.

C6 (6.8nF) and R10 (100KΩ) make a power up reset for the CD4017. If you don't require a power up reset omit C6 and use a 10KΩ resistor for R10 or connect pin directly to circuit ground using a wire jump.

If you want the PCB layout (Eagle) PM me your name and email address.

You might omit the ground fill on the PCB, but I recommend to use it for the reasons of saved etchant and less copper to poison our environment.

My inbox has been emptied in the meanwhile.

Regards

Boncuk

P.S. Send your accidently ordered NE555 chips to me. :) I just can get DIP packages here.
 

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Boncuk. I am talking with Max in chat.

He wants to etch the PCB but needs an image in black on a white background without the silkscreen. Or he can work from the eagle files.

Thanks
3v0

Hi 3v0,

I have no problems leaving the original Eagle files to Maxx. If he wants them he should PM me his name and email address.

Regards

Boncuk
 
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