Looks like these units are manufactured by Labmetric, they also sell a variant of this instrument as the "Ohmstar" for quite a bit less than the one from IET with slightly different specifications.
Hey @ddrl46, good eye! Yep, we’re Labmetric, a small team here in Arizona assembling each unit ourselves (and debating resistor tolerances over way too much coffee). Thanks for giving us a shout-it’s a big deal for a team our size to get noticed.
What a coincidence, just looked at the listing of this thing today. "Slow" reading update is because you have digital filter engaged on K2002. By default that's moving 10 filter, so you need 10 samples to get fresh new value fully refreshed. You can also null out the offset by using MATH NULL, when IET box configured to source "0 ohms". Also calling adjustment procedure by "calibration" is non-metrologically sound ;)
Talk about timing, xDevscorn_EE! Clearly, the universe wants you to think about resistors today. We’re just a small team here in the US trying to make precision tools a little less frustrating for engineers like you. I encourage you to join the resistance! If you’ve got any questions or feedback, we’re all ears-our team loves geeking out over this stuff!
I made a resistor substitution box. It is a matrix of 4mm sockets with resistors between them. There are a few thick jumper cables I can use for summing values, but most values I can get with no switch contacts intervening.
Hi donepearce, love the DIY spirit! That’s exactly where the Ohm Source started-just a couple of us brainstorming ways to ditch the fiddling and improve precision. We’re still a small team here in the US, and trust me, every resistor we solder reminds us of how much we respect setups like yours. Hopefully, we’ve saved some engineers a bit of wiring frustration along the way!
A good additional feature would be a 0.1ohm 10 turn potentiometer so you could adjust it to _EXACTLY_ the resistance you want. The low values are reading a bit high.
At the other end of the scale from the OS-270, I purchased a cheap decade unit from Aliexpress with 1% SMD resistors and manual selected with jumpers. I can see the benefits of an electronic version, but none that I would use. If I needed precision, I would tune the jumpered resistance values with a potentiometer. Time consuming but workable.
You may want to watch behavior of this thing under oscilloscope. It might get really nasty spikes at the moment of switching. It does not make it useless, but it is a thing that needs to be considered
I'm curious about what latching relays are used, and how they are configured. I would hope that there is an option to select the switching behavior. Without thinking about it too deeply, there are at least three useful behaviors. The obvious ones are the equivalent of make-before-break and break-before-make -- short the output before selecting a new value, or open the output before selecting. For some uses a more reasonable behavior would be limiting the excurion from the target value, either minimizing the difference or always being minimally higher or lower. It's obvious why you need to have the right behavior with a ratiometric divider of a voltage regulator, and the safe switching behavior depends on which side of the divider the resistance box is on.
Given all the resistors above and below, it seems it should be able to dial in almost perfect values with a detailed enough adjustment routine. I was wondering, if you did a manual bisection search through entering custom values, how close can you get it to perfect orders of 10 values?
I have designed a resistance box myself after considering to buy this one first but then realizing that it is not precise enough. The one I built can do 1 Ohm to 1.6 Mohm with 0.001 Ohm of resolution. It also uses very low EMF relays. But it is a lot bigger, the size is roughly that of the usual half 19 inch devices like Keysight 34401 multimeter. I also added all sorts of ratiometric devices to the menu. Usually I use it for PT100 simulation and simulation of saltwater conductivity.
Hey ChipGuy, that’s impressive-sounds like you’ve put a lot of work into your design! As a small engineering team based in the US, we totally get the drive to build your own solutions. The Ohm Source was actually born out of that same desire for precision and reliability. Our latest version has tighter specs and an improved form factor, and we’re always refining it based on feedback from engineers like you! We just made a huge improvement to our software, making it even easier to integrate into automated systems.
Awesome idea to use ratiometric devices! I have too designed a programmable decade box. Mine is from 999.999999 megohm to 1 ohm with resolution of 100 milliohm. The best feature of my device is to calibrate automatically when connected to a PC with a keithley 2001. After updating the calibration offsets, it is +-500 milliohm on any set value, even up to 100meg. The calibration process is very slow, though.
pretty neat little gadget! unrelated: whats the difference between a TSP and TNP video? I haven't quite been able to discern the logic behind that😅 Is it just the video length?
The major consideration with this (and other "substitution" boxes) is the RF characteristics. It is not good, but more troublesome is that the frequency response, and RF characteristics vary, since it changes the path through the resistors and relays to ensure you get the exact R value you want. Keep the signals below 1 MHz, and you'll be OK. This was designed and built by a friend on mine to develop and calibrate Conductivity and PH test equipment.
Hey @shazam6274, you nailed it-RF quirks are always a fun (read: annoying) part of the game. The Ohm Source is very much a DC and low-frequency tool, which is where our small team focused all our energy. We’re not trying to play in the GHz sandbox yet-maybe one day when we have a bigger coffee budget! Appreciate the technical insight-it’s great seeing these kinds of discussions.
I just started my electrical engineering and wanted to explore. Found this channel luckily but I'm not able to surf thru the channel, it is confusing. Can you please tell me how to go thru the channel?
@@ansarraza6855 I am not sure what you mean by “surf through the channel”. Every video title is as descriptive as possible and the video description gives you more details.
sometime I wonder if there is something like infinite resistance.. I mean technically .. or will it be something like 4.2x10²³¹³²³² Ω from one side of the universe to the other. 😅
Long before you get to such an extremely high resistance, you would notice that electrical charge is quantized and equations like Ohm's law that assume a continuous electrical current are only approximations, so the meaning of "resistance" becomes ill-defined at some point, I think. You will always have some tiny non-zero probability of charges tunelling through even the best isolator, so I think the answer is: No, there is no such thing as infinite resistance.
You quickly venture out of 'resistance' into 'charge transport'. Resistance is an approximation that is good enough to solve most problems, just like classical Newtonian physics is good enough for almost every use. Thinking about how much mass photons would have if photons had mass doesn't help the spherical cow approximation.
When you search price of this little gadget, you probably will still using your vintage decade resistance box with rotary switches style..Unaffordable to me..🤯
Hey Bob, we hear you-this method is tried and true, and we still keep some of those classic resistance standards from IET’s past in our own shop. The Ohm Source, though, is more like a precision scalpel-it’s there when you need spot-on accuracy without the guesswork (or the hair-pulling). As a small US-based team, we’ve got plenty of old-school tools on our workbenches, too-they’ll always have a special place in our hearts (and toolkits)!
Looks like these units are manufactured by Labmetric, they also sell a variant of this instrument as the "Ohmstar" for quite a bit less than the one from IET with slightly different specifications.
Hey @ddrl46, good eye! Yep, we’re Labmetric, a small team here in Arizona assembling each unit ourselves (and debating resistor tolerances over way too much coffee). Thanks for giving us a shout-it’s a big deal for a team our size to get noticed.
Note that an updated nearly identical device is available from LabMetric for about 1/3 the price mentioned in this video.
What a coincidence, just looked at the listing of this thing today. "Slow" reading update is because you have digital filter engaged on K2002. By default that's moving 10 filter, so you need 10 samples to get fresh new value fully refreshed. You can also null out the offset by using MATH NULL, when IET box configured to source "0 ohms". Also calling adjustment procedure by "calibration" is non-metrologically sound ;)
Talk about timing, xDevscorn_EE! Clearly, the universe wants you to think about resistors today. We’re just a small team here in the US trying to make precision tools a little less frustrating for engineers like you. I encourage you to join the resistance! If you’ve got any questions or feedback, we’re all ears-our team loves geeking out over this stuff!
@@maxmetrix4256 We? :) Resistance is futile but would be cool to see more players in metrology. PPMs market does feel a little bit stale these days.
I made a resistor substitution box. It is a matrix of 4mm sockets with resistors between them. There are a few thick jumper cables I can use for summing values, but most values I can get with no switch contacts intervening.
Hi donepearce, love the DIY spirit! That’s exactly where the Ohm Source started-just a couple of us brainstorming ways to ditch the fiddling and improve precision. We’re still a small team here in the US, and trust me, every resistor we solder reminds us of how much we respect setups like yours. Hopefully, we’ve saved some engineers a bit of wiring frustration along the way!
A good additional feature would be a 0.1ohm 10 turn potentiometer so you could adjust it to _EXACTLY_ the resistance you want. The low values are reading a bit high.
At the other end of the scale from the OS-270, I purchased a cheap decade unit from Aliexpress with 1% SMD resistors and manual selected with jumpers. I can see the benefits of an electronic version, but none that I would use. If I needed precision, I would tune the jumpered resistance values with a potentiometer. Time consuming but workable.
You may want to watch behavior of this thing under oscilloscope. It might get really nasty spikes at the moment of switching. It does not make it useless, but it is a thing that needs to be considered
I'm curious about what latching relays are used, and how they are configured.
I would hope that there is an option to select the switching behavior. Without thinking about it too deeply, there are at least three useful behaviors. The obvious ones are the equivalent of make-before-break and break-before-make -- short the output before selecting a new value, or open the output before selecting. For some uses a more reasonable behavior would be limiting the excurion from the target value, either minimizing the difference or always being minimally higher or lower.
It's obvious why you need to have the right behavior with a ratiometric divider of a voltage regulator, and the safe switching behavior depends on which side of the divider the resistance box is on.
1:11
BCF Status, RP0
BSF Status, RP0
Aaaargh, bane of my life.. (but fun, at the time)
Given all the resistors above and below, it seems it should be able to dial in almost perfect values with a detailed enough adjustment routine. I was wondering, if you did a manual bisection search through entering custom values, how close can you get it to perfect orders of 10 values?
I have designed a resistance box myself after considering to buy this one first but then realizing that it is not precise enough. The one I built can do 1 Ohm to 1.6 Mohm with 0.001 Ohm of resolution. It also uses very low EMF relays. But it is a lot bigger, the size is roughly that of the usual half 19 inch devices like Keysight 34401 multimeter. I also added all sorts of ratiometric devices to the menu. Usually I use it for PT100 simulation and simulation of saltwater conductivity.
Hey ChipGuy, that’s impressive-sounds like you’ve put a lot of work into your design! As a small engineering team based in the US, we totally get the drive to build your own solutions. The Ohm Source was actually born out of that same desire for precision and reliability. Our latest version has tighter specs and an improved form factor, and we’re always refining it based on feedback from engineers like you! We just made a huge improvement to our software, making it even easier to integrate into automated systems.
Awesome idea to use ratiometric devices! I have too designed a programmable decade box. Mine is from 999.999999 megohm to 1 ohm with resolution of 100 milliohm. The best feature of my device is to calibrate automatically when connected to a PC with a keithley 2001. After updating the calibration offsets, it is +-500 milliohm on any set value, even up to 100meg. The calibration process is very slow, though.
pretty neat little gadget!
unrelated: whats the difference between a TSP and TNP video? I haven't quite been able to discern the logic behind that😅 Is it just the video length?
Generally TNP videos are (potential) repairs or smaller tear downs, no?
Noise Path is for stuff he's moreso repairing, Signal Path is for stuff he's moreso demonstrating.
The major consideration with this (and other "substitution" boxes) is the RF characteristics. It is not good, but more troublesome is that the frequency response, and RF characteristics vary, since it changes the path through the resistors and relays to ensure you get the exact R value you want. Keep the signals below 1 MHz, and you'll be OK. This was designed and built by a friend on mine to develop and calibrate Conductivity and PH test equipment.
Hey @shazam6274, you nailed it-RF quirks are always a fun (read: annoying) part of the game. The Ohm Source is very much a DC and low-frequency tool, which is where our small team focused all our energy. We’re not trying to play in the GHz sandbox yet-maybe one day when we have a bigger coffee budget! Appreciate the technical insight-it’s great seeing these kinds of discussions.
I just started my electrical engineering and wanted to explore. Found this channel luckily but I'm not able to surf thru the channel, it is confusing. Can you please tell me how to go thru the channel?
@@ansarraza6855 I am not sure what you mean by “surf through the channel”. Every video title is as descriptive as possible and the video description gives you more details.
Hell yeah, fresh signal path!
sometime I wonder if there is something like infinite resistance.. I mean technically .. or will it be something like 4.2x10²³¹³²³² Ω from one side of the universe to the other. 😅
Long before you get to such an extremely high resistance, you would notice that electrical charge is quantized and equations like Ohm's law that assume a continuous electrical current are only approximations, so the meaning of "resistance" becomes ill-defined at some point, I think. You will always have some tiny non-zero probability of charges tunelling through even the best isolator, so I think the answer is: No, there is no such thing as infinite resistance.
You quickly venture out of 'resistance' into 'charge transport'.
Resistance is an approximation that is good enough to solve most problems, just like classical Newtonian physics is good enough for almost every use. Thinking about how much mass photons would have if photons had mass doesn't help the spherical cow approximation.
When you search price of this little gadget, you probably will still using your vintage decade resistance box with rotary switches style..Unaffordable to me..🤯
I have never used one of these...I always use a Potentiometer instead....
Hey Bob, we hear you-this method is tried and true, and we still keep some of those classic resistance standards from IET’s past in our own shop. The Ohm Source, though, is more like a precision scalpel-it’s there when you need spot-on accuracy without the guesswork (or the hair-pulling). As a small US-based team, we’ve got plenty of old-school tools on our workbenches, too-they’ll always have a special place in our hearts (and toolkits)!
Eh, I'd still rather have and use the one on the left, at the end. Just saying.