Would... (but already did)
Thx Star :)

this keeps getting better and better

Groth
I understand the need/benefit of the optical isolation (std in other things),
but how does that resolve the floating ground issue, or is it then moot ?

Care to guess how much it'd cost to ship a kit transatlantic timelord?

Groth,


That circuit looks pretty easy... can you give me a part number on the optical isloators.


Bill,

moot (I think... Groth verify :D )

By isolating the two busses optically, you are never actually connecting the two devices to the same power supply and can power the measureing devices on a separate PSU without the floating ground issue.

Butcher,

It could fit in a letter sized evelope or one of those larger letter bubble pack ones...

How much?

count me in for one unsoldered

I'd get one or two soldered

Spoon fed, eh? :D

The isolation is of course only an issue if you want to measure the voltages of a target system from another PC, the temperature reading circuitry is internally isolated.

Powering the reader IC from the target computer eliminates the ground float related to current return though the PSU power cords, plug, and some wall wiring (if you don't have your two computers plugged into the the same socket). You still have the potential for float/noise from things like the ATX connector, long strings of molex connectors, wimpy power planes, etc.

My prime concern was the CPU power. Accurate measurement of Vcore was more important that accuracy of 12V, or Vdimm, or any others. So I grounded the reader IC at the back of the CPU socket. It's ground will float relative to others' due to the 60+ amps the CPU can dump into the ground plane, but it's ground will match the CPU's ground. Not allowing for that float overestimates Vcore and CPU power.

So, yeah, the bus optoisolator resolves between-computer ground float/noise. And it moots local float/noise if you ground it to match your measurement of interest.

MMZ_TimeLord, I used Digikey part number PS8701-ND (I like SMD), but TLP550-ND would work just as well. I'm sure there are others, they just have to be faster than around a microsecond, to keep the bus from timing out.

spoon fed ? LOL
you bet (Thanks), I last studied electronics in the Navy in '63
- a bit different then, always been catch-up since - topic by topic

You can put me down for a 6655!!!

My international shipping (letter envelope, USPS Global priority) was about $6. I had the packing materials already, but if you wanted to account for that it would be around 7 or 8.

thanks pug :)

Add me
 

You can also put me down for a 6655.
Thanx :cool:

Update!

I hope to have the sample 6655s (two) and the 1668s (two) by next week. I should be able to make the prototypes at that time.

I may go ahead and make the optical isolator board for those that want it. I should be able to add the additional board and parts at minimal cost to the first kit.

Give a shout if you're interested in that board too. :D

setup as a separate board ?
probably more interested in those than the 6655s

any specs ?

Groth has mentioned the part number for the Optical Isolators (DigiKey# PS8701-ND)... I would presume (pending Groth's verification) that the transistors could be SMD and general purpose types. Resistors would probably be the same package I'll be using for the temp modules (0805 type).

Other than that there wouldn't be much to it... SMBus connectors on each side with the same pinouts as the temp modules, for consistancy. :p

As to the design... I'm looking at Groth's schematic from his link. I would be interested if he has completed version 3 or has an updated version with recommended part numbers. That way you would get what Groth has already verified as working.

I don't know enough about electronic circuits to verify or trouble shoot designs like that. But I'd be willing to add that to the board runs so everyone could be happy... not just me. :D

That schematic is the final version of the isolator (the version .3 referrences were to the ammeter it was isolating). I've put that very circuit in into a couple things without problem.

The choice of transitors is very forgiving; I used some bog standard SOT-23 packaged, type 2n3904 and 2n3906 that I had around. The resistors can easily be the common 1% tolerance, tenth-watt 0805.

The only thing that might give folks problems is the 'optional resistor'. SMBusses can use either 5V or 3.3V signalling. 5V devices will function correctly with 3.3V signals, so I made it 3.3 on the slave side. On the master side, you have to match the existing signal voltage (easily checked with a multimeter). A jumper would be way cool, to make that selection easier.

I'll take a couple of the isolators if they're separate.

MMZ_TimeLord
kudos for the effort you're putting into this great geek stuff
(of course Groth too)

BillA,

No problem, I am only trying to return some of what I got from this wonderful community [/brown-nose] :D

Groth,

Yeah, I could do a jumper with no problem for that. I'll see what I can get up on here for a design today. Kinda slow here at work anyways... (BORING! :p )

would the unsoldered kit have solder on the pads already? so all you have to do is place the component and apply a little heat? or is this going to be a happy-hacker real DIY thing?

the idea of soldering tiny SMD things makes my eyes hurt lol

i am interested in two of the unsoldered kits with voltage/temp monitoring...

great project, cant wait for an update :D

well hello there shirley

do something cool for this forum too :D


everyone, this is one of the smartest guys in the computer scene.

So MMZ_TimeLord...how is this project is going?

Just wondering...

Sorry I've been away... Got laid off on the 24th of May, so I've been a little preoccupied. :cry:

I do have the design for the optical isolator circuit almost done. I will then be putting up the final designs and part numbers for review.

After everyone seems happy, I will post an e-mail for placing orders. I hope to get enough to make purchase of the parts worth it all.

Until then... please be patient ... thanks... :D

I'd like one or two, but I am a little confused on my options...will go re-read the thread, or if someone could sum it up, that'd be great

so the 1668 has 4 remote sensors, and a 5th onboard?

what is being offered here by MMZ_TimeLord?

oh man that blows, my condolences!

OH man that really sux. I feel your pain. I've been off since the end of February. Put me down for one of the dual 6655s. Hopefully shipping to up here in Canada is not too much.