Picture of Wireless home router with analogue utilisation meter
I grew up in and around boats making wiring looms and control panels, and have a collection of gauges & dials that would normally be found connected to small marine diesel engines.

Today I work as a designer building interfaces to networking equipment. As such, I like re-using the old analogue gauges to display network information in a more human readable analogue form. Tying my past to the present to some degree.

I used a 3" rev counter, simple clean design, that came of one of the boats my dad owned when I was a kid and wired it in to a wireless router I had lying around at work.

The rev counter is a rough approximation of the traffic utilisation between my home network and the internet.

Step 1: Overview of how it works

Picture of Overview of how it works
There are a number of ways to find out how much bandwidth is being used. This being the first pass at a digital to analogue conversion of the utilisation, I opted for simply using the uplink LED as an indication of the amount of traffic passing between my home and the internet.

This has some serious limitations. I do not know whether the hardware (broadcom chipset) or firmware (dd-wrt) contains the sampling algorythm that drives the LED, probably the chipset. Here's the first issue, an LED must be on for around 30mS for the human eye to register it properly. Networking packets are much much shorter than this. So the router must do a little math and translate real network traffic in to slower LED blinking. So there is a sampling loss, the LED is a rough approximation of the actual traffic.

Then, I must boost the 3.3V which drives the LED up to 14V required for the rev counter (most automotive dials and meters like this are linear 0-12 or 14V) For this I used a basic op-amp circuit. Without some swanky Digital to Analogue conversion I again loose a lot of resolution.

In the end, this is not a very good representation of the traffic bandwidth being used, but the further I got in to the project, the more it became an interesting object of art and less a solution to the original problem.

Note: I've been working with the guys from http://dd-wrt.com/dd-wrtv2/index.php I highly recommend you upgrade your current software to this feature rich open source firmware.
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Freshbott24 years ago
Would it be possible to display how much download has been used in total in a month?

You see, in Australia, our service providers are stingy and give download quotas according to how much you pay for your service. Running over this quota means you have one of two choices, use your connection at 60kbps until the monthly reset, or pay heaps of money for data blocks.
radiorental (author)  Freshbott24 years ago
That is a fantastic idea. They've started doing the same thing in Canada I hear.

Two things you could do.

1) The DD WRT software that runs on the linksys (& similar routers) tracks how much network you use. You can set it up as a server and then with software (I forget the name) on your computer... just track it that way.

2) In the same theme as this instructable, in parallel to my circuit you would need to build another circuit that counts the LED flashes. Figure out what the total count is for your bandwidth cap and then it's up to your creativity to display that.

My circuit is analogue, to figure out a gauge for the bandwidth cap you will need to do some programming somewhere. An arduino might be overkill but could be the easiest option. Digital in - count it, drive a fuel gauge with the same 5 to 12v op amp circuit in this instructable

Hope that helps

Sounds like I've got a future Instructable on the way!
radiorental (author)  Freshbott24 years ago
feel free to ask any questions -good luck
ddewson6 years ago
I have to say I was browsing out of boredom and I am amazed at the creativity that goes into some of these projects. Although I may never use this particular piece I will say that it is an amazingly creative work. The thought put into making it a) Work and b) look so good. Congratulations! it is a stunning work.
It will be a sad day when someone uses this design for one of those 10 inch "Ricer" tachs with the big shift light mounted on top of an LCD. Great Instructable though, although, I agree with eliminating the opamp in favor of a BJT or FET.
kanika6 years ago
hey i also need to make a project but purely on maths if u have an idea contact kanika_thecoolgal@yahoo.com ur idea is too gud . i really got inspired
agis686 years ago
excellent job and nice idea....bytheway.....i have the same VDO rmp console from my dad's old car....(DKW -AUDI 1957)
Vyui37 years ago
Is there any way I can get a copy of that 'icon strip'? I'd love to do something similar to this, and I absolutely adore what you've done here. -- Thanks
Too Cool
Esque7 years ago
Very very cool, a little more embellishment and it would be incredibly steampunky :-)
jimtran937 years ago
this is so f***ing amazing

great job =D
K8ROX!!!7 years ago
I like this web site it is fun and cool
frenchfrie7 years ago
mrsayao7 years ago
i was wondering about heat issues? my linksys wrt wireless gets pretty warm... anyway, do you have any pictures of the back of the unit??? great job, your creation is damn sexy!
wasgij57 years ago
he3r07 years ago
This is awesome, I really love analog gauges like that in computer equipment. I will definitely try to do this since i have a couple of routers that I do not use. Also I have a question, How difficult would be to wire tach to show processor speed?
Love it. But I think your idea of the wooden case might be the best part ad suggest you contact D-Link and such and see of they wouldn't be interested in doing a line of "wooden" routers and such. I suspect the industry never thought of anything but the "high tech" look when designing accessories for the computer/network and that, now that the Home Networking is a bigger thing, it might well fit in nicely. Imagine your "box" as a wireless cable modem w/or w/o the speed dial! The "industry" could replicate the style with a cheap Chinese blow mold and adapt it to hang on a wall or sit prettily upon a desk. Send me 1% of gross sales of you pull this off 828-394-0035 Charles
Nice work! The whole package screams art deco and puts a new twist on tech cabinetry. Adding this one to my favorites. BST
ewilhelm8 years ago
This project was mentioned here in the New York Times!
momo!8 years ago
This is truly inspiring! And I think it's damn rad that it's as much personal as it is functional.
true_geek8 years ago
this is freaking awesome, you have spawned many new ideas into my head like adding a gauge to show how many connections or IP's are being used on the network. hmmmm.....
Mourtegoul8 years ago
Hiya. Is it really necessary to get into OpAmps at all here? I don't really know much about the tachometer, but I'm assuming it displays proportional to the applied voltage from 0-12v or 0-14v from the descriptions. Why not use the square wave output that's driving the activity LED to drive the base of a fairly hefty BJT between one pole of the tach' and ground, and tie the other end of the tach to 12volts? Is the tach' inductive?
radiorental (author)  Mourtegoul8 years ago
Very true, there is any number of solutions to the problem. Some suggested a microcontroller. The op-amp works, and I will look at a simple transistor. The thing to think about is smoothing, with a flat out sqr wave driving the meter you will notice every little 'blip', I wanted some form of cumulative gain. Even with the op-amp I have achieved the desired output, it still swings a lot. Thanks for your feedback
Goose12208 years ago
Defenetly a GOOD conversation starter... "Hey what the hell is that??" "Oh.. It's nothing really..just my homemade... and so on and so forth..." 2 thumbs up :)
thrudd8 years ago
Good point about the router power needs.

Simplest solution would be to take your +12v output and split it with a ladder bridge. Energy wasteful but easy to build and pretty much rock solid.
Next is just feeding the +12v into a +5v regulator circuit (chose your flavour).
The last is just salvaging a small enough switching supply with the needed voltage outputs. (ah salvage) =D
maestro8 thrudd8 years ago
The output impedance of a ladder bridge is so low that it is not suitable for use as a power supply; a ladder bridge is best used for a voltage reference, as when sourcing a comparator (which ideally draws zero current). Simply put, the more current one draws from a ladder bridge, the more the output voltage will sag (towards 0V). Remember Ohm's law!
thrudd maestro88 years ago
D'oH .... you have me there . But with the bridge havinging a smaller efective resistance than the load there is negligible effect, besides, you always design with the load already known right? (joke) A better suggestion by me would have been just as cheap, a zener diode regulator setup. Heck, most cheap (ahem price point) brick dc supplies use the design. Goes to show you how much knowledge you loose when you dont use it. *sigh*
I'm sure this message was intended to be (dare I say it) coherent. But with ladder bridges, solid rocks and feeding 12 volts into 5, you lost me, although my preferred "flavour "is lemon. I'm still busy chipping away the corners on my new invention: I call it "wheel", but am concerned about lawsuits with the dang thing rolling away. Can you elaborate for us dummies? Thanks!
I believe he was referring to powering the router by either a resistive divider circuit on the 12 volt supply, or by using one of any number of 5 volt regulator ICs, such as the LM7805. This would make it unnecessary to provide separate 12 volt and 5 volt power sources.
radiorental (author)  cylver8 years ago
resistor divider = ladder, I thought thats what that was - thanks!
radiorental (author)  thrudd8 years ago
You'll have to forgive me, I was off sick the day they went over ladder bridge... can you send a link, I couldnt find anything I have a few 24v wall warts lying around, I expect that I can somehow get -12, 0, +5 & +12 out of that, right?
cylver8 years ago
One thing that would improve the project would be to include variable resistors in series and parallel with the meter movement, to fine-tune the range and offset. If I were making this, I'd use the op-amp as an integrator, to measure the duty-cycle of the LED directly, then put a pass transistor at the output to control the meter movement.
maestro8 cylver8 years ago
Connecting resistors to the meter would change its impedance; a better solution would be to correct the behavior of the op-amp... using variable resistors in the op-amp would allow one to make the same adjustments.
radiorental (author)  maestro88 years ago
I have a variable pot controlling the op-amp. The issue with the 741 I used was that its output is a range within its supply. That is, it never reaches down to 0V. I am looking at better amps and building a dedicated switching psu for these devices. Thanks for your help/advice on the design.
thrudd8 years ago
Ah, I can see why you are not ever getting a zero signal and never max out either. Try a split supply setup for the amp plus a few more passives to tweek the circuit balance. You can dig out a useful circuit from any old Op amp cookbook. You should then be able to get your zero reading at least. The other thing to note when working with mixed op amp circuits is that they are challenging to run rail to rail when you want to (and do when you dont want to) XD
maestro8 thrudd8 years ago
A split supply is unnecessary to achieve the "zero signal" you seek. An LM358, or any op-amp with a FET in the final stage (such as the 3130/3140) will give you output voltages that are within millivolts of the bottom rail. As for your choice of circuit, an integrator would be a better use for the op-amp. Your current usage could be accomplished just as well with a transistor or two. Furthermore, you don't need the 7404s since most op-amps draw fractions of microamps of current (much, much less than the LED in the router). Build the low-pass filter into the feedback loop of the op-amp to keep its input impedance high (to ensure it draws a minimum of current) and you won't have to worry about overloading the router's output signal.
radiorental (author)  thrudd8 years ago
thanks very much, when I get around to rev'ing this design I'll get in contact. Didnt want the initial complexity of a split supply... but I now have a few more designs in mind I might do a small production run. Some routers like 5v, the linksys's like 12... so I should maybe create -12, +5 & +12v rails?
You can find meter gauges at electronic surplus stores. Ugly, but functional. Check JC Whitney for analog car gauges. Pretty and pricey, but hey, you only need one, and they're backlighted! Of course an auto wrecking yard might have a battery gauge which would work, or maybe that old "beater" in your neighbor's back forty? "The only thing better than Wholesale is Free." -D
xhx8 years ago
Why not use a printed overlay in the gauge? You could print one up like you did with the other front panel displays. Just open it up, pull out the old overlay, and put in the new one - you could make it display whatever you wanted.
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