Hello

I need some help with a working design. I would like to build a 5 LED ( SMD 0603 in that size/shape range) circuit. The circuit should turn on LED1 then off then LED2 on then off till LED5 same thing then start at LED1 again in order.

I would like to use a 555 I.C with a 5 - 6v range, main battery. I would like to be able to adjust the flash rate to speed up or slow down the flash rate.
I want the circuit to be as small as possible on a circuit board because of size restrictions; 1"x1" or 1"x2" in that range.

For my First attempt, I would like to use 5 average LEDs on my experimentors board to see if it works and get assembly practice.

Hope someone can help me with this circuit.

Thanks

George

 

A 74HC/HCT4017 chip will take a clock input from the 555 and drive up to 10 LED's at 4-5ma (in sequence - one On at a time).
It works on a 5VDC power supply. This is one way to do it.

See page 15.

View attachment 74HC_HCT4017.pdf

 

If you want to do only 5 LEDs in sequence then connect output "6" to the reset input of the 4017.

 

Is this small enough (0.5 by 0.65 in?)



one PIC12F1840 (or other 8-pin pic) in SOIC 8 package
one 0603 100nF bypass capacitor
5 0603 LEDs (top row)
5 0603 resistors

Bob

 

Whoops, I missed that fact that you wanted an adjustable flash rate. So it is now 0.5 x 0.9 in. with the addition of a trimpot. Fortunately there was 1 pin left for the analog input from the pot.



Bob

 

Or, if you prefer the 555 and 4017 route:

1 555 SOIC-8
1 4017 TSSOP-16
1 capacitor, 1 resistor 1 trimpot for 555 astable
1 tank capacitor
5 LEDs
5 current limiting resitors

1.0 x 0.6 inch

Probably need a 2 sided board to wire this, the PIC based one is 1-sided. I didn't route this one.



Bob

 

Hi BobTPH

Thanks for your help and circuits. I forgot to mention that the LEDs are NOT to be mounted on the board BUT are wired and mounted elsewhere and the wires get soldered to the board.

So next question, since I can`t make the boards myself, how do I get them made and the PIC, do they require a program? Where is that done?

George

 

Assuming you are a hobbyist and need only a small quantity, Osh Park will make 3 double-sided boards with all the bells and whistles (solder mask, silk screen) for just $5 per square inch. That come to $3 for the board I posted! You use Eagle (PCB CAD software) to design the board, and just upload the file to order. A limited version of Eagle, which would be fine for these boards is free.

I have my first order with them in progress right now, so I can't comment on quality until I receive it, but, from everything I see, it looks like they will be professional quality.

If you are not familiar with PICs, you might be best to go with the 555 / 4017 version since no programming would be necessary. If you do want to go with PICs, you need to get a programmer, the PICKIT 2 or 3 are recommended. All the tools you need for programming are free from Microchip. Do you have any programming experience? You can write in either assembly language or C.

Since you said you wanted to use 0603 LEDs, I assumed you are okay with surface mount soldering, is this true? These things are smaller than you think! I usually stick with 0805 or larger myself. You would still want the LEDs on a small PCB, would you not?


Osh Park: http://www.oshpark.com/

Eagle: http://www.cadsoftusa.com/

Microchip: http://www.microchip.com/

Bob

 

Hi Bob

Thanks for the info. I do not have any experience with Pics or their programming. So I think I will go with the 555 and 4017 combo. I like your circuit design you posted. As for the LEDs Yes they 0603 OR 1206 either or should be ok with me, I will see later. The LED`s are soldered onto Very thin wires and then each attached in a circle and covered in a plastic cap. that way when they are operating, it looks like a safety light on a heavy construction vehicle.

I can run it off of my main model battery; 12v or 6v with a 5v regulator to supply this circuit. Which is better for this circuit, 5v or 6v supply?

Since I have NO idea about that circuit design you said, any chance you could email me the deign circuit or whatever it is called and tell me how to get it to the circuit board maker OR is it too hard to try to make a working circuit from a point to point circuit board?

I want to make sure with the 555 and the 4017 I have the ability to adjust the flash rate.

Thanks Again for your help.

George

 

Hi Bob

Thanks for the info. I do not have any experience with Pics or their programming. So I think I will go with the 555 and 4017 combo. I like your circuit design you posted. As for the LEDs Yes they 0603 OR 1206 either or should be ok with me, I will see later. The LED`s are soldered onto Very thin wires and then each attached in a circle and covered in a plastic cap. that way when they are operating, it looks like a safety light on a heavy construction vehicle.

I can run it off of my main model battery; 12v or 6v with a 5v regulator to supply this circuit. Which is better for this circuit, 5v or 6v supply?

Since I have NO idea about that circuit design you said, any chance you could email me the deign circuit or whatever it is called and tell me how to get it to the circuit board maker OR is it too hard to try to make a working circuit from a point to point circuit board?

I want to make sure with the 555 and the 4017 I have the ability to adjust the flash rate.

Thanks Again for your help.

George

Hello George0039.

You originally stated using a 5 volt supply. If you can use a 12 volt battery
then a normal 555 with a CD4017 would work on the 12 volt supply.

Point to point is quite difficult with surface-mount devices. Thus the PCB pattern generously supplied by BobTPH.

 

Hello tubeguy

So will this circuit then work with either a 6v main battery with No 5v reg. feeding this circuit OR a 12v main battery with NO 5v reg. feeding this circuit. Just direct power to the circuit from either main battery?

I looked again at the circuit drawing BobTPH graciously supplied. I am NOT sure but are those pads for the LEDs on the circuit pattern? If they are, I only need soldering points for the LED wires to the board plus a variable resistor so I can adjust the flash rate.

Most important question, when BobTPH can draw that circuit with my modes in it, how do I get that to the circuit board maker, which the link BobTPG also graciously provided.

Thanks Again for Both Your Help.

George

 

Do you know how big an 0603 is? It is about 1/16 in. in length! You do not want to try to connect wires to this. If you want them in a circle, I would make a circular PCB for it. How big? You might be able to get the whole circuit on there.

The Design I did for 555 and 4017 was not complete, it had all the parts I think were needed, but I did not do the connections. The PIC one had the connections, except that I noticed since that one trace was missing (the ground for all the LEDs).

I did these with ExpressPCB, free software from another PCB manufacturer that I have used in the past. They are much more expensive than Osh Park. Osh Park is so cheap because the way the work is to batch many peoples small PCBs onto one large sheet that can be handled as a single PCB by the manufacturer. They then send out the entire batch, and cut it up afterwards. They take about 2 weeks from order to delivery.

You didn't answer my question about surface mount soldering. If you have not done this before, you are in for a surprise. But don't despair, I learned how to this at 59 years of age, (which much help from magnifiers).

So let's slow down a little. My PCB layouts were just examples of what you might do, not finished products. You first have to let us know what your experience level in soldering PCBs is. Then we should develop a schematic, then a PCB. It sounds to me like you would rather have it done for you. I think you should learn how to do it yourself.

So, to summarize, please answer the following two questions:

1. What is your experience level in soldering components to a PCB?
2. What is the size of the circle of LEDs that you want?

Bob

 

Hello tubeguy

So will this circuit then work with either a 6v main battery with No 5v reg. feeding this circuit OR a 12v main battery with NO 5v reg. feeding this circuit. Just direct power to the circuit from either main battery?


George

George.

Read the chip numbers that I mentioned carefully.
The 74HC4017 works on 5 volts only, but will supply enough current to operate LED's directly.

If you can use 12 volts then the CD4017 can be used without a regulator because it works at up to 15 volts.
With a 12 volt supply it can sink enough current on the output to drive a LED directly.
But as the supply voltage decreases, so does it's available current output.
This is common behavior with the 'CD' CMOS family of logic chips.

 

Hi BobTPH

Sorry I forgot to mention that I have already soldered the wires to the 0603 LEDs. I have lots of experience with soldering surface mounted devices. I just can`t design or fabricate the circuit boards.

My other problem, little one I think, is I`m NOT sure if I will have a 6v or 12v main battery. So my question to you is will the circuit still work with either and I don`t need a regulator then.

George

 

It depends what version of 4017 you use.

 

Hello Again

I just finished measuring the area where the main battery will go. I will have to use a 6v, not enough room for a 12v.

So from now on, only dealing with 6v main power for everything including this flasher circuit, which I can put a 5v reg. on to supply 5v if needed.

George

 

Hi BobTPH

Thanks for getting back to me. I don`t know what happened but I thought you were going to get me a schematic circuit for what I wanted?

George

 

Well, I think you said that you were trending toward the 555 4017 solution. I would not feel comfortable doing a schematic using those chips unless I actually built it. Others here would be better suited to the task.

I basically gave you a circuit using a PIC, in the form of a PCB (though it has an error and would have to be revisted.) If you want to pursue that route we could continue.

Bob

 

Hello again BobTPH

Yes lets go with the pic version. When you can, I appreciate the help.

Thanks Again.

George

 

The trouble with a PIC version, is that you have to program it. You will need a programmer and a lot of learning.

Bob