computer Christmas lights

[MrDEB]

years ago I assembled a Compurterized Christmas light display but since sold the entire setup.
I recall the SSR or triac boards used an opti-isolator, couple resistors but instead of using a computer, I want to just use a PIC to drive the opti_isolator. Just started looking for leftover plans and parts but figure would ask first.

 

[For The Popcorn]

4 leds at one time (one of each color)

Not quite. You can turn on 1 – 4 LEDs IN A GIVEN ROW.

You can't turn on LEDs in different rows, say the upper left red and lower right green at the same time for example. What will happen if you try? Unless you are actually multiplexing at > 30 and turn on ONE LED at a time. Then more than one can appear to be on at a time, with reduced brightness.

 

[MrDEB]

My proposed plan is to turn on row 1 then row 1 off turn on row 2=on then off row 3 = on then off row 4 on then off
repeat

 

[For The Popcorn]

If your plan is turn on one row at a time, why are you supplying V+ from port pins?

Good luck. You're going to need it.

 

[MrDEB]

The Anodes of the LEDs are connected to port pins C.3 to C.6
Cathodes are grounded when desired row is grounded
V= from port pins? got confused thinking I have V+ connected directly to the rows?

 

[MrDEB]

I think I am ready to pull the trigger and order circuit boards

 

[Pommie]

You seem to have the 12V and ground connections as nice thick tracks and your 5V connections very thin. And, is there any capacitors on your layout?

Mike.

 

[MrDEB]

2 caps next to the 5v regulator (top left) and one next to the pic .(pin 19 & 20) Thinking of adding another to pic (pin 20 & 8)

 

[MrDEB]

Made slight addition, added a heat sink on the circuit board for the 7805 voltage regulator.
Been worried about the heat generated by the 7805 going from 12 volts to 5 volts.

 

[Pommie]

I guess your not bothered by the (very) thin trace carrying the 5V supply?

Mike.

 

[MrDEB]

I used the default of .203mm
can increase to .300 or ?

 

[Pommie]

What are the trace widths that are feeding the regulator? All those traces are carrying the same current so should (you would think) be the same width. However, if you're happy with 0.2mm (about 8 thou) then carry on.

Mike.

 

[MrDEB]

Good point
here is revised PCB
has pad for heat sink on 7805 and all 5v and 12v nets are .700mm wide

 

[MrDEB]

An issue I have been thinking about, but need some advice.
I have 32 wires that connect the 16 LEDs to the circuit board.
On the right side of the board pictured I have 16 sockets, but can change to?
Looking at FFC FPC, wire to board or? only 10ma max per wire.
so many different choices.

 

[Pommie]

only 10ma max per wire.

That must be incredibly thin wire. Do you have a link?

Mike.

 

[MrDEB]

some really thin wires from the LEDs to the PCB. Been contemplating different ideas.
These are what I have the LEDs soldered to

100Sets Micro JST 2-Pin Pitch 1.25mm Single End 15cm Wire To Board Connector | eBay

Type: Micro JST 2Pin Wire Connector. Micro JST 2Pin Pitch 1.25mm Single End Wire To Board Connector 100. Length: 15cm. Plug Pitch:1.25mm. Quantity:100 Sets(100Pcs Wire Connector + 100Pcs PCB Socket ).

www.ebay.com

plan to only toggle 4 LEDs at a time (RED, WHITE, BLUE, GREEN)
The link shows some really thin wires, thus stripping to allow soldering. Thought about just adding a length of wire (26g) but would entail two soldered joints per wire.
Last idea is start over with the LEDs and solder the 26g wire to each smd LED.

 

[MrDEB]

Decided to just bite the bullet and redo the SMD LEDs glued to the white plastic.
Connecting 30g wire wrap wire to 26g wire has issues with stripping the small wires in the link I posted.
Thanks for looking at solutions, but will redo the LEDs then solder the 26g wire to the LEDs instead of the 30g wire wrap wire. Redesign the PCB to conform to changes.

 

[Pommie]

I was wondering about the 10mA maximum per wire. Even 30g can carry 860mA according to this page.

Mike.

 

[MrDEB]

I used the wire wrap for the solder connections on the SMD LEDs as well as the LED/Neon strips. It's small and easy to conceal. The single LED is is connected so 10ma or less per LED.

 

[shokjok]

My Christmas light switcher uses a 555 timer feeding a 4017 counter I.C. connected to 4 4N25 optos feeding heatsinked TIC125 triacs wired to open AC outlets. A 9v wallpack powers the switcher. The flash rate is programmable with a trimpot.
My unit has worked outdoors down to -35C/ -31F.

 

[MrDEB]

nice idea but for a better light controller, perhaps look at using a microprocessor.
I have 5 boards ordered but only need one. If you want one PM me.