There a few tutorials out there which describe how you can add 4 (5) new temperaturesensors to your system using the Smbus and the Maxim 1668 IC. Here are two english ones:
http://www.madhacker.org/mbmsensors.htm
http://www.overclockers.com/tips1059/

And a good german tutorial with a lot of pictures, worth seeing even for people who don't understand german.
http://www.andreas-lenz.de/casemods/de/max1668.php

I thought I need somenthing like that so I made one similar to the german tutorial. It worked and I was satisfied at first. But then I thought I could make a better looking one and at the same time give it a little protection against short circutis and stuff.
I was inspired by my T-Balancer and those are the consequences:
At first I will show you the size of the Maxim 1668 IC which you have to solder on the PCB:


That's how it looked in the end:











The sensors are simple transistors which I made smaller with a Dremel. You might get them even smaller than I have now, but you might damaged them. It would not be a great problem because they cost only a few cent.




The first time I etched (I'm not sure if it's the right word) the PCB in simple bowls. It worked but it was difficult to get the right temperature. Therefore I searched a little bit on the net and made this:



It's made out 4mm polystyrol you can get it here in a lot of places and it sn't very expensive. I cut the polystyrol in pieces of the size I wanted and glued it together with normal plastics glue. I got the heater and the air pump for a few euros on ebay, they are normally for fishtanks.
With this equipment the etching went a lot better.

I hope you liked it and if anyone of you is interested it isn't very difficult to build something like that. You can get free samples of the IC from Maxim. And also the other stuff isn't to expensive at least not in Germany. It's nice to have additional 4 (5) sensors which you can use for example together with the T-Balancer.
If you have any questions feel free to ask.

Damn nice......just how did you cut the clear plastic covers so perfectly? Soldering small stuff is easy, but only after practice, with good equiptment, with good eyesight or a large magnifying glass, and a lot of patience.

I guess I'm a control freak...always wanting to know what's happening, temperatures, etc. I've used DigitalDoc 5 units to check temps. This device is a good alternative....if you've got the correct MB connector.

Thank you.
Yeah I think I'm a control freak too. Add the 4 sensors from the mainboard to the 5 sensors of the T-Balancer to the 5 new sensors from this device. Well that would be 14 temperature sensors =)

I cut the plastic covers with a circular saw. Then I used a file to rounden the edges. And to get the whole thing clear I used different kinds of sandpaper and then a I used a piece of cloth and polishing compund to get it clear. It's not difficult but it will take some time.

At the moment I'm thinking of making a PCI card to use this device on mainboards without the correct connector. I'll keep you informed.

Webfire, that looks a superbly simple solution... are you tempted to etch a few more, solder them up and sell them...?

I use mini-itx systems so don't need a controller for multiple fans and sensors, and also would prefer to hook something up to the I2C pins on the motherboard and use Speedfan and SMBus to monitor temperatures and adjust fan speeds.

The new Via EN boards allow fan speed control (see HERE), and they have a 3-pin I2C header (SMBCK, SMBDT and GND). I only need a couple of extra sensors, would your circuit be ok for this with the Via board with 3 pins?

This is all new to me, so sorry if questions are a bit dumb

It is a basic question, but could you give me the specs of the connectors you used?

I have sourced all the other stuff I need for a temp guage like yours (though based on an LM84 IC) But searching catalogues for connectors is hard.. too many choices, and most of them look the same

They look like molex ones?

Most importantly, what is the connector you use to attach to the smb?

wow! How did I miss this before?!

Unfortunately webfire hasn't logged on to spcr for about a year, so wouldn't get my hopes up for a reply. You might want to see if he's still active at silenthardware.de

I figured out the molex question anyway, Someone at bit-tech gave me a very obvious solution. Try pin headers from a fan, they are .1' as it happens.

Got a coulple of maxim 1668 chips to try it with and some pcb board.

Looking for a good pcb designer thats preferrably free.

I've used ExpressPCB before, they have free software that you can download. Then you can either etch it yourself or pay them to make it.

I'll try it. Being playing with Eagle tonight. Proving difficult for me, but new things always are till you get good at them.

Might give Express a try tomorrow, see if it is more my cup of tea.

What method of transfer did you use? I'm torn between toner or photo etching. Got a kit which will let me try out both.

And I'm full of nerves about soldering that ickle chip...



This piccie gives a good impression on just how small it is.. My camera wont focus on it even.

I simply sent my stuff to them to make. It was for my work, so I didn't have to foot the bill. And it was 4 layers. I've never etched myself, so I can't offer any advice there. Let us know how it works.

If you break out the soldering skills you can use an SMD transistor as a sensor as well. The clear goopy stuff is a bit of hot glue I added to prevent shorts.



EDIT: Actually I could make up an Eagle schematic and board for you guys, but MAX1668 isn't in the standard library. I'd have to search for it or make it up.

So are you saying there's no real need to buy sensors from places like M-Cubed? ...even though these digital ones are free (here are the analogue ones, I don't know the difference...)

M-Cubed have just brought out a Semipassive Kit for ATX power supplies.

Looks interesting, have emailed some questions to them. I use mini-itx cases, so don't need the multi-sensor complexity of the T-Balancer, but it would be great if this could be put in the hottest part of the case and it worked off the SMBus with Speedfan...

I'm sorry that I haven't been too active lately, but I had a lot of work to do in university. Exams and stuff, but I have some free time now.
I didn't know that there so many question here. =) Leem wrote me a PM but I thought that was the only question. I will try to answer all your other question later this day.

@Leem: I looked at the manual of your mainboard and I think it should work fine. The only thing you need is 5V from somewhere. e.g. from a fan header or from the 4pin nt connector.

I just received some new ICs from Maxim a couple of days ago. A new 7 channel precission one , I have to see if I can get one of those working.
And I'm still working at a pcb which you can put in a RAM Slot for people without a smbus connector on their mainboard. Like myself with my shuttle mainboard in one of my PCs. But my two prototypes haven't worked yet. Perhaps with new ICs to experiment I find a solution.

I got mine working the other night. I will have to post a photo.



Stuck it onto a pcb which I designed in ExpressPCB.



I used an OHP to print a photo-resist board with the design, I have put other stuff onto the pcb that I am still trying to get to work. Got a few cables still to make up etc. Hence been too busy to phot and post. I haven't made up the probes yet, but the local temp is just fine, and the remote sensors are behaving as they should when I attach/detach jumpers.

Things I have noticed so far

The accuracy I achieved is superb. I measured it the air temperature at the surface of the chip with a medical thermometer. The two are measuring identical temperatures. Maxim claim =/- 1c, I seem to have achieved a fraction of that error margin.

The local temp is not very responsive however to sudden changes in temperature. I sat the board on my cpu heatsink, then took it away again, the temperature took quite a few minutes to drop down.

The soldering of the maxim chip was a breeze, I had doubts wether I could pull it off, but it turned out to be real easy. Just use a decent amount of flux, clean the contact pads thoroughly and the rest looks after itself.

Here are some piccies of the board, My camera doesn't like closeups, so please be understanding of the fuzziness.




Big thanks Webfire for bringing this one to the attention of the forum here, when I saw it a few weeks ago I just had to give it a try. Truth is i dont really need it that much, but it was fun to build, and it stretched my skills.

I already saw that you figured out which connectors to use. But I can try give you some more information anyways.
They are the same ones used for fan headers, also called molex. I just found a british shop who sells them:
http://www.maplin.co.uk/search.aspx?Men ... s&doy=30m8
They are called 0.1" PCB Header Plugs there.
I used them to connect the sensor cables but also for connecting the PCB to the SMBUS.

Concerning the method of transfering, I used photo etching. I printed the PCB on a transparent film using my inkjet printer. I found an old sun lamp from my mother which was standing around so I used that one to transfer the layout on the PCB.

The only thing I'm not quite satisfied yet are the sensors. The SMD transistor are a nice solution, but they could be smaller yet. Perhaps I can find something better somewhere.

Nice to see that some people are interested in this device and people are trying to make it themselves.
If anyone has more question feel free to ask.

Edit: Just saw your results from your etching. Looks really nice, the picture could have been a little better =)
You got a lot more stuff on there. What's that?
It's nice to have a lot of stuff together but I don't know if you might get some interferences. Another improvement would be a ground shield (I hope it's the right word) saves you your etching solution and makes your electronics less sensitive to intereferences.

I ended up using Molex kk .1' headers and plugs, Got them and all the other components bar the maxim chip and the pcb from Farnell.

The challenge was finding the pins that matched the molex sockets. This was really tough, I stumbled on the right ones eventually. There are a bewildering array of molex sockets on the market, its a pain.

My design is slightly different to yours, component wise I used a .1uf radial cap, alu. I also used two 10k pullup resistors accross the data and clock lines as recommended by Maxim. The length of my traces between the chip and the caps is smaller, as is the distance between the caps and the headers. I downloaded the design you used and tried to toner transfer it, but was not happy with the accuracy I was getting on the print. In the end I got ambitious and decided that I would prefer to do my own design... Allowed me to add the extra stuff, and also it was satisfying to learn something new.

I would be interested in how you rate your for accuracy. I would guess them to be the same unless the line filtering cap or the solder used made a difference. I noticed in the datasheets that the solder resistance of the solder can affect accuracy for te remote sensors.

I dont think it matters to me, for my purposes even =/-3c is more than accurrate enough.

Just saw your edit.

I possibly should have used a grounded shield, wasn't sure which ground point to attach it to. I know the answer should be them all. But as the grounds were coming from the smb, the graphics card and the psu, I was nervous that in fact they may have caused issues. I have only ever star grounded before.

The other stuff is from top down.

Below the maxim is a set of pass through traces for the vga signal I am feeding to my psone screen. I put a gap in, and thought that the signal would be unlikely to interfere.

Then there is a 24lc21 chip. Its an edid that will hopefully tell the graphics card the settings to use on the psone screen. Should mean I dont have to run powerstrip. Its untested so far.

Below that again is a 350t voltage regulator. Having troubles with this, you might be able to help.

Its supposed to take a 12v line down to 7.5 v for supplying the psone screen. I can adjust the output with an adjustable resistor. I plugged it in, and adjusted it to 7.5.

Then I plugged the psone screen in... It didn't do anything.

So next I checked the voltage accross the output. Now its measuring half the voltage? Any Ideas what I have done wrong?

I also had some difficulties with the connectors in the beginning.
We have a nice german online electronics shop where you can find the right molex connectors. www.reichelt.de

Well I haven't read the maxim data sheet when I made the PCB you can see at the beginning of the page. So when I make a new one I will include Maxims design recommendations.
I know the accurracy isn't too important but when I'm doing something I want it to be as best as possible.
When I get the chance to check the accuracy from mine I will post it here.

You also got some more stuff on there what's the VGA thing?

Edit: Just saw your new message, nevermind my last question.

The pullup resistors on hte data lines AFAIK are only to tell the smb bus that it should comunicate. I'm pretty sure that they dont affect the accuracy of the thing. It may be that an IC bus requires them and SMB doesn't. i included them cause I had 10k resistors in my toolbox doing nothing, it seemed daft not to include them.

I take it you cant help me with my voltage regulator issue?

I think you may have used the wrong pins on your LM350T. In your drawing the furthest left pin is connected to Vin, but National semiconductor says that is the adjustment pin. You also have the Vin pin of the LM350 connected to the 7.5V plug.

National's website is confusing, they show a schematic with the chip connected like you have it, but the pinouts are different from what's shown in the schematic.

That was indeed my error. Rerouted a bit a bit of jump wire and the thing is working now.

Thankyou for helping out...

Blair

Well time for the glamour shots... Here is my take on the maxim 1668 temperature controller.



And here is the soldering job on the chip...



And the repair job on the power regulator circuit...



Still got some flux to clean up, but the repair is not to bad..

All in all I am pretty happy with my first attempt. Might try and make a second one, might just be happy with what I have?

I have no use for it myself, but I might pick up a 1668 from Digikey and make up an Eagle layout and board for it. What about other diode sensor chips? Like the LM83 looks like it handles 3 sensors and is $6 rather than $10 at digikey.

I looked at the LM74 which if I remember did 2 remote sensors, higher quoted accuracy. I would have gone for it to but maxim kindly sent me a couple of sensors.

The LM seriers works of a 3.3v input, I was going to use a fixed voltage power regulator and a couple of caps to get the right voltage. The maxim chip on the other hand takes a wider range of input voltages.

I guess that for our purposes the accuracy of any of these chips is fine and dandy. My local sensor at least is working well within the +/- 1c that maxim quote.

I didn't really get to grips with eagle, expresspcb was easier for this noob to pick up and learn.

If people want only 1 or 2 extra sensors, there are plenty of cheap chips out there with internal sensors. The MicroChip TC74 is only $1.39 from Mouser.com and it comes in a easy to wire TO-220 package, though it's a fairly large package. It's both the sensor and interface chip in one, so all you need to do is run the SMBUS wires to it. No board or seperate sensor is needed.

This is interesting but how do you connect it to your mobo? Will it connect to a dfi lanparty ut?

In my case my mobo has a 4 pin riser that connects directly to the SMB (system management bus) bus. It wasn't labelled, but the manual for the mobo identified it. It was in a standard .1' 5 pin header, with one pin removed. I used a molex 1' 5 crimp pin enclosure, leaving one of the holes cableless.

I'll post a photo later.

I have read that on some boards the SMB riser is only 2 pins (Data and Clock). This is still ok for use with these chips. The other 2 of the SMB bus pins on the 4 pin header are for 5v and Ground. These could be be taken from anywhere really.

I dont know the dfi board, but a quick scan of its manual should tell you what you need to know. Just skim it for SMB bus. The SMB is really just a modified version of the IC2 bus as pioneered by intel. This IC2 bus will work also with all of the temp monitoring chips that are designed for SMB... Well the ones that I have seen anyway.


Hope that helps... Its an interesting project to build one of these, I can give you the benefit of my (very enjoyable) experiance if you need further help.

Blair

I2C (Inter-Integrated Circuit) was invented by Philips.

Sorry my bad... AFAIK and I am no expert, the IC2 first appeared on Intel boards. Not that it matters if I'm wrong.