Rewiring An Old Router to Blink

It's been a few years since I fiddled with electronics. But, a recent project has me digging out my old breadboard and ordering parts again .

Basically, the goal is to rewire an old busted router to appear powered up, and a couple ports blink as if it were a working router. It's primarilly to irritate an over-zealous network admin here at work who will definately flip out if he saw a non-standard router on someone's desk blinking away, but I don't want to spend an arm and a leg on putting it together.

I'm guessing I'll use a 9v battery, or possibly an external power supply - I'm not entirely sure yet. I'd like to keep as much of the router in it's original form as possible, as I'd hate to waste and have to re-engineer LED alignments etc.

The board for the router is definately multi-layered, so I'm not sure if scraping the topmost and bottom most tracings around the LED's solder-pads and directly soldering to the existing "stands" of LED's will be ok - but I can't imagine that it should be an issue.

Originally I thought to try and get a pseudo "random-ish" looking blink, I'd have two or three 555 timer circuts, one to do the fast-blinking, and a second (or third) to switch on the blinking through a transistor. By using two "switching" timer circuits at slightly varying cycles, I'd get a more random-ish "switching on" of the blinking.

This is probably overly simplistic, but I've not touched electronics for some time, and I'm not familiar enough with PIC programming or even where to get parts for some of the ocillator circuits as suggested in some of the other threads involving randomness. I'm pretty sure I've got enough parts to put together a handful of your standard 555 "LED blinking" type circuits, but would be open to getting additional parts if necessary.

Any ideas or suggestions or feedback would be greatly appreciated!

A site note, as I was digging through my old prototyping gear, it looks like my old multimeter was damaged beyond repair. Logic probe is still in tact, but any suggestions on a decent multimeter? I'm not afraid to spend money on a good one if anyone has any suggestions.

Thanks again!!!

 

A real router is so cheap($29.95) and I assume that your time is valuable. So I can't imagine why you would want to spend time on this project. If you just want a reason to get back in the swing of things then just open the router case and throw away the circuit board inside.

LED alignment? Glue new leds to the pannel and use flying wires to connect them to the circuit board. This project is supposed to irritate your boss -- not you.

Start by connecting each LED to its own oscillator. Tune the oscillators to different frequencies. They will beat against each other for an interesting pattern.

After you get this working you can try some variations. Learn to crawl before trying to run a marathon.

Multimeter? Wavetek has some fine ones for under $100.00

Hope this helps

 

Thanks PB!

The goal is to have a router that looks like it's working, but really isn't (we really aren't supposed to have any outside networking equipment). So using the shell of an existing router seemed like the easy choice, and having it run off a 9v battery makes it easy to carry around without having to plug it in.

I thought about just directly gluing LEDs in the faceplate, but the way the router comes apart, it will be increadibly difficult to get down into the faceplate to glue anything. But given your suggestion, I'm guessing my original plan probably won't work as I think anyway. Oh well.

Thanks again for your help, and the multimeter tip . My poor Fluke died a horrible death.

 

It shouldn't be too difficult. You could use an NE555 timer to make an oscillator and drive a few transistors to flash the LEDS. Could all run from a 9V battery as you suggested.

 

Thanks for the reply WK.

I'll have to dig up my old EWB CDs and see if I can whip up a schematic, see if it makes sense what I'm thinking. What I meant by it won't work, is my original throught to try and basically keep the guts so the existing LED stacks (LEDs are in plastic housings) still align with the holes in the front face. I was basically going to dremel around the stacks to separate the LEDs from the old circuitry and wire them from their existing pads at the bottom of the circuit board. Keep them on the board, but just scrape away the old traces. I think that's what PB was referrring to not working.

Any suggestions on where to pick up parts? I'm not going to pay $2 for a resistor at Radio Shack .

 

You could try Digikey. they have everything.

 

Well, I've got my circuit all setup and working. I've got one other strange issue. The circuit is designed for running on a 9v battery, but when I use the 9v adaptor (DC/300ma), the blink-pulses are really irratic. Is there a better alternative for an external power supply?

 

I'm assuming that it is 9 Volts DC. Check the unloaded output; you would be surprised how high the open circuit voltage on one of those things is. The specification is that the output will be about 9 volts WHEN the load is drawing 300 mA. If your only drawing 3 mA the output voltage can be just about any higher voltage.

You could add a regulator to the wall wart's output.

 

Thanks everyone for your help with this. What I ended up doing was using two identical 555 timer circuits that output into a a NAND (LS7400N) gate. The two circuits are adjusted using 20k trimmer pots so they are slightly out of sync (100k & 70k respectively). This gives an offset output between them.

The output of the NAND drives yet another 555 circuit (with trimmer at around 4.7k) that actually blinks the router lights in a believable way that mimmics the traffic blinking you would see on a regular router. I've taken the output from the NAND to an inverter (LS7404N) to drive the opposite blinker to give the illusion of a file copy between the two ports. The pdf does not show both "output" 555 blink circuits due to space, but the upper-most LED was replaced wiht the secondary blink circuit.

I've attached the circuit in the hopes it may help someone else. Feel free to critique!

Thanks again!

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