## One Gigaohm resistors

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I was creating a BOM on the Mouser website and I came across this:

No typo.  1 to 50 GIGAohms.  The 50Gig was 30% tolerance, but the 1Gig was listed with a tight 1%.

I guess my question is.....What would you need a resistor of that size for?  I have rarely gone over 3.3M.

I might have to see what a meter to measure that would cost.....

I checked - \$500.00usd

http://www.ilovefluke.com/Fluke/...

Jim

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

"The critical shortage here is not stuff, but time." - Johan Ekdahl

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB user

Last Edited: Fri. Feb 1, 2019 - 09:07 PM

The first question that raised in my mind was "what's the resistance of fresh air?". In other words, why bother with a resistor at all - why not just leave a "gap"?

However this seems to suggest that the resistance of "nothing" is considerably more than GigaOhms:

http://electronics.stackexchange...

though it obviously depends on how big the "gap" is.

If it's roughly 2x10^16 per metre then that presumably means 2x10^13 per millimetre? That's 20 TeraOhms per millimetre is it?

1. Found its application in megger calibration, insulation measurement device claibrator etc.

2. You can actually measure it by placing a 1M in parallel. With just 1M & no other resistor, meter will measure exactly 1M. But with 1G in parallel, it will measure around 999k

Edit typo: corrected to 999k. Typically cal labs have devices to measure these resistances

Last Edited: Mon. Jan 11, 2016 - 04:22 PM

Don't think I would have use for 5GOhms, but somebody must or nobody would manufacture it.

So, what happens when you breathe on it?

"We trained hard... but it seemed that every time we were beginning to form up into a team, we would be reorganized. I was to learn later in life that we tend to meet any new situation by reorganizing. And a wonderful method it can be of creating the illusion of progress while producing confusion, inefficiency and demoralization." Petronius Arbiter, approx. 2000 years ago.

Lets see, 5V, 5GOhm -> 1nA

Must be some use for that!

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

I have seen very odd resistors in CO2 laser power supplies.

jgmdesign wrote:

I guess my question is.....What would you need a resistor of that size for?

Current to voltage converters for really small currents, leakage etc

Very high value resistors are used in some electrostatic field controlled devices, for focus and bias electrodes.  IIRC, I ran into a string of 10MO+ resistors (200MO+ total) in an old "build your own infrared sniperscope" project, and I would imagine that there are other similar applications.

what size resistor? and package.

I could imagine that if one works in the kilo volts range you also want extreme high impedance if you have a voltage booster going to KV range it might not deliver high current thus you want to limit that.

It can also be a safety measure in a lower ohmic/current environment were if the current rises to much you want to trigger something.

Highest value I have product wise used so far is 10Meg Ohm in a measurement setup we sometimes use 40Meg (4x10) to ensure that the probe does not load the system and causes measurement failure(or a circuit that works when the scope probe is attached but stops working as soon as you remove the probe, that was an irritating problem....

Vishay's TR30 range of thin thick film high voltage resistors range in value from 80M to 3T ohms with a 5% tolerance. Stick that in your pipe and smoke it...

edit. corrected to thick

Ross McKenzie ValuSoft Melbourne Australia

Last Edited: Wed. Jan 13, 2016 - 06:12 AM

Quote:
The 50Gig was 30% tolerance [...]

Ah, that would be due to Johnson (or thermal or Nyquist) noise, which is being produced by all resistances. Given that Johnson noise is present in every circuit, and often puts a limit on noise performance, it is a bit surprising that it was not discovered until 1928 by John B. Johnson at Bell Labs.

Johnson noise bandwidth theoretically goes all the way up to daylight, but in the real world is ultimately limited by the shunt capacitance of the resistor in question. Johnson noise is not produced by reactances --i.e. pure capacitance and inductance. In the real world, however, all the reactive components are never pure...

The RMS amplitude of Johnson noise is easily calculated with the formula:
U = SQRT(4kTRB), where:
- U is the RMS noise voltage,
- k is Boltzmann’s constant (1.38e-23),
- T is absolute temperature in °K,
- R is the resistance in Ohms and
- B is the bandwidth in Hz.

This is a table of Resistances and their Johnson noise at 25°C and, say, 100 kHz bandwidth:
Resistance    Noise voltage
(Ω)        (μV RMS)
-----------------------------
1        0.041
10        0.128
100        0.406
1 kilo        1.28
1 Mega        40.6
1 Giga        1,283
1 Tera        40,558
1 Peta        4,055,811 (yes, this is more than 4 Vrms or 32.9 Vpp of thermal noise!)

Not to mention any additional, strong or weaker, noise sources like the Poisson (or Shot) noise, the 1/f (or flicker) noise, the Popcorn noise, etc., all being nasty traps for young players...

-George

I hope for nothing; I fear nothing; I am free. (Nikos Kazantzakis)

Wow. 3T is a LOT of ohms.

Perhaps you'd use something like this in "hi-pot" testing where you put a big voltage across something that's supposed to be insulated: If you measure a voltage across the 3T resistor, something's not right.

"We trained hard... but it seemed that every time we were beginning to form up into a team, we would be reorganized. I was to learn later in life that we tend to meet any new situation by reorganizing. And a wonderful method it can be of creating the illusion of progress while producing confusion, inefficiency and demoralization." Petronius Arbiter, approx. 2000 years ago.

Last Edited: Tue. Jan 12, 2016 - 03:15 PM

Can you fellas keep it down in here?  I can hardly hear my self tinker!

 "Experience is what enables you to recognise a mistake the second time you make it." "Good judgement comes from experience.  Experience comes from bad judgement." "Wisdom is always wont to arrive late, and to be a little approximate on first possession." "When you hear hoofbeats, think horses, not unicorns." "Fast.  Cheap.  Good.  Pick two." "We see a lot of arses on handlebars around here." - [J Ekdahl]

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

"The critical shortage here is not stuff, but time." - Johan Ekdahl

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB user

jgmdesign wrote:
The 50Gig was 30% tolerance, but the 1Gig was listed with a tight 1%.

Note the similar situation in the Mouser screenshot below.  0 ohm resistors have various tolerances.  So, what would be the low and high ohm values for a 0 ohm resistor with 30% tolerance?

And the power rating runs from a few mW to a few W.  I broke my calculator trying to use Ohm's Law and W=I*V to determine the allowed amps...

;)  The 'Freaks have been down the 0-ohm path before.

https://www.avrfreaks.net/forum/w...

https://www.avrfreaks.net/forum/w...

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

Last Edited: Tue. Jan 12, 2016 - 07:36 PM

Lee,

My OP was done knee jerk reaction as I had NEVER heard of such a high value resistor before.  Much less with the specs posted.  Actually, I really haven't taken it too seriously, until your post, and even that is pretty funny when you think of what it would take to overload one of these units.

Jim

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

"The critical shortage here is not stuff, but time." - Johan Ekdahl

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB user

I am just glad they aren't priced by the ohm!

JC

valusoft wrote:
Stick that in your pipe and smoke it...
No ... it's up in smoke due to one's brain fart.

There's nothing like creating a high voltage mistake.

What's that smell?

Vishay

Resistors, Fixed

TR, TD

Thick Film Planar Resistors and Dividers, Through-Hole, High Voltage

http://www.vishay.com/resistors-fixed/list/product-68000/

"Dare to be naïve." - Buckminster Fuller

Giorgos_K wrote:
all being nasty traps for young players...
One does not have to be young to be trapped; been there, done that

Giorgos_K wrote:
... noise sources ...
A use for such in pseudo (but nearly true) random number generators; "The Art of Electronics" (third ed., pages 982-984, base-emitter avalanche).

"Dare to be naïve." - Buckminster Fuller

Corrected above.

Ross McKenzie ValuSoft Melbourne Australia

DocJC wrote:
I am just glad they aren't priced by the ohm! JC

I guess they are way more expensive than lets say a 10K or 100K resistor, just because they are a lot harder to make and will be used far less.

so that might be true, though not linear as had in mind when writing this.

the 0 Ohm 5% tolerance and power discussions are always fun to have. specially with engineers that are fresh out of school or that have a high hat on themselves but have been nothing else then paper pushers in the past. They indeed think that a 0R resistor is 0R and love to push amps through them and still expect the voltage drop to be 0 Ohm. Or engineers who are reluctant to put a 0R resistor in for safety in a circuit that max does 1mA because of the possible voltage drop......

gchapman wrote:
One does not have to be young to be trapped; been there, done that
Who hasn't?

Alright, next time I'll ditch the euphemisms! :P
What I meant was that anyone, despite of age or expertise, *is* a young player in every new field for them.

Quote:
A use for such in pseudo (but nearly true) random number generators;
That is correct.

The popular method was the use of the reverse-biased B-E junction of a BJT (to work as a Zener) or an actual Zener diode as noise generators. The problem with Zener diodes is their relative low noise output because they are designed to produce minimal noise. On the other hand, the BJT solution needs a relatively high voltage junction bias (>7V) for today's 3..5V (or even lower) voltage supply circuits. The same relatively high voltage bias requirement applies to the resistor noise generators also, in order to produce a usable noise amplitude output. So, the preferred noise generators today are digital, using very long sequences to produce in return tightly defined (in amplitude and spectral content) noise.

-George

I hope for nothing; I fear nothing; I am free. (Nikos Kazantzakis)

In their wisdom, the governments will, surely, some day ban resistors---since they waste power

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

I used a 100 Mohm / 10 Mohm voltage divider to measure high voltages in a Cockroft-Walton circuit with my 10 Mohm multimeter.  The higher resistance was helpful in not draining the capacitors so fast the multimeter couldn't get a reading.

Interesting necromancy...

 "Experience is what enables you to recognise a mistake the second time you make it." "Good judgement comes from experience.  Experience comes from bad judgement." "Wisdom is always wont to arrive late, and to be a little approximate on first possession." "When you hear hoofbeats, think horses, not unicorns." "Fast.  Cheap.  Good.  Pick two." "We see a lot of arses on handlebars around here." - [J Ekdahl]

joeymorin wrote:
Interesting necromancy...

https://www.avrfreaks.net/forum/...

Was split from here.

I'll lock this one

JIm

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

"The critical shortage here is not stuff, but time." - Johan Ekdahl

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown