Whatever happened to this product?

[dknguyen]

A pot is not the same as a fixed resistor in terms of stability.

And where and in what would you need such a form of stability that also needs to be configured, where you would not just be better off with a fixed resistor?

Wrong. SFRs were pulled from the market long before resistors became inexpensive. If they were still viable, it is not beyond reason that their machine produced large quantities would be competitive with fixed resistors.

Ratch

I think this is wishful thinking because you can get "precision" (which for the purposes of argument I'm going to say is 1% or less) through-hole resistors en masse for under a penny. Less than half a cent for 5% tolerance. Do you recall the precision and stability for these?

I don't think so. Your argument on raw cost alone does not take into consideration the convenience of one unit being the able to substitute for several different resistor values, or having to go to the trouble of maintaining a stockpile of resistors.

I think those are all moot because they are heavily outweighed by cost per part and size (PCB real-estate also costs money) in mass production.

Even hermaphroditic B2B connectors are shockingly rare and yet they have none of the previously outlined drawbacks of the SFRs with regards to cost, size or space. You don't even need to add any complexity a lot of the time to make them hermaphroditic because they already have so many bits and pieces to them...that you just have to rearrange the existing parts, more or less. There's practically zero downside to them.

That is what I would like to find out. It is possible that economics was not the reason. Perhaps they were not as stable or trouble free as a discreter resistor would be. I don't know, but it would be interesting to find out.

Ratch

Then you would be best just e-mail Bourns and asking. Because the way I see it, there are plenty of reasons why they would not be viable on the market if they were introduced right now. I also have doubts about your claims that resistors may have been expensive enough in the past to warrant such a thing.

Not the least of which is that they do not lend themselves to mass assembly, not only because of cost and size but also because the way they need to be configured. You would need to mask them in a separate operation (which is tricky since they aren't level with the board) and then run them through the process a second time. Or have some poor sucker sitting there configuring them all.

 

[Ratchit]

Ask a question, and then argue with the logical replies. Guess it wasn't really a question.

Ask a question, then argue with answers that do not necessarily make sense. Guess I did not get a reasonable answer.

Ratch

 

[dknguyen]

Ask a question, then argue with answers that do not necessarily make sense. Guess I did not get a reasonable answer.

Ratch

I don't think that word means what you think it means. But seriously, you should ask them because I want to see the odds that it's one of the reasons already mentioned which you already rejected out of hand.

 

[Ratchit]

And where and in what would you need such a form of stability that also needs to be configured, where you would not just be better off with a fixed resistor?

I guess you would not if you can make something that goes together correctly the first time and does not need any rework. Then you can look at it as say, "That fixed resistor I was wondering about sure was cheaper than a SFR. I sure hope we don't need to change it."

I think this is wishful thinking because you can get "precision" (which for the purposes of argument I'm going to say is 1% or less) through-hole resistors en masse for under a penny. Less than half a cent for 5% tolerance. Do you recall the precision and stability for these?

No I don't. I am not saying that SFRs in their initial form would be competitive in today's market. But I still wonder if they were taken off the market because of economics.

I think those are all moot because they are heavily outweighed by cost per part and size (PCB real-estate also costs money) in mass production.

I am wondering why back then why they were on the market for such a short time. Yes, things are different now, and no doubt they would not be viable in their past form. But what about yesteryear?

Even hermaphroditic B2B connectors are shockingly rare and yet they have none of the previously outlined drawbacks of the SFRs with regards to cost, size or space. You don't even need to add any complexity a lot of the time to make them hermaphroditic because they already have so many bits and pieces to them...that you just have to rearrange the existing parts, more or less. There's practically zero downside to them.

Connector are connectors and resistors are resistors.

Then you would be best just e-mail Bourns and asking. Because the way I see it, there are plenty of reasons why they would not be viable on the market if they were introduced right now. I also have doubts about your claims that resistors may have been expensive enough in the past to warrant such a thing.

That is an idea and maybe I will.

Not the least of which is that they do not lend themselves to mass assembly, not only because of cost and size but also because the way they need to be configured. You would need to mask them in a separate operation (which is tricky since they aren't level with the board) and then run them through the process a second time. Or have some poor sucker sitting there configuring them all.

Until you hold one and look at it, your speculation on how they are made is dicey.

Ratch

 

[Ratchit]

I don't think that word means what you think it means. But seriously, you should ask them because I want to see the odds that it's one of the reasons already mentioned which you already rejected out of hand.

Maybe I will ask them. I don't necessarily reject your economic reasons, but you seem to keep comparing today's technology and economics to yesterday's.. I can't help thinking that Bourns did take economics into consideration. I think it is very possible that another factor contributed to the SFR demise.

Ratch

 

[be80be]

I seen one of these it was used to set a LM317 it was in a computer main board.

 

[JonSea]

 

[be80be]

You Know Jon do you remember when there was like 5 CPU that fit the same mother board they all fit but the core needed different voltage I did see something like this some had jumpers which is good as long as you set them and leave them but I think even you had some problems with jumpers. Maybe not.

But I one board it had something Like this you could change the core voltage. Maybe where The was thinking cause those days ran by fast 6 months and them
mother board's was off the market.

 

[JonSea]

That wasn't me Bert. Never actually built a pc from pieces.

 

[be80be]

I think you even had some problems with jumpers.

I thought it was you that said you got some jumpers and they was bad sorry if it wasn't you

But I seen this happen a lot bad jumper bad CPU LOL

I just figured you had come across the bad jumpers

Like I said one used this kind of resistor setup and you soldered to set but the next CPU came out fast new boards which it probably why a part like the SFR never made it nowhere.

 

[MrAl]

Hello,

As to the original product, i can see uses for it but they will be limited.

It's basically a resistor substitution box in miniature, but solderable so that it can be permanent.

Of course resistor sub boxes have limited use because of power and frequency, but for hobby stuff like Arduino it would be good to have some as long as they were not expensive.

Another product like this is a min sub box, made from a dip switch and several value resistors. You can get a wide range of resistances but again it is limited as to what you can actually use it for (probably no RF for example).
I would not mind having a few on hand though, for sure.

 

[DerStrom8]

You guys are having the exact same argument I imagine the engineering/sales departments at Bourns had. Obviously the side pushing the release of the product won out, but the real market showed what the "correct" answer was. It may be useful in niche applications but generally speaking, it must be easier, cheaper, or both to use discrete resistors. Otherwise this product would have thrived and would probably still be prevalent today.

It's just a case of a company trying to determine what the market needed and simply making the wrong choice.

Ratchit To answer your question, they aren't really anywhere anymore, except maybe in someone's garage or old lab. The closest modern product I know of is probably the programmable resistor modules from Pickering Interfaces, and it's basically just a bunch of resistors with relays to switch them in and out of circuit. Generally they're used to mimic resistive sensors in test fixtures or used as voltage dividers that can be changed on the fly. Once again, very niche applications, and a completely different (more convenient) method of doing it.

 

[gophert]

but I imagine that one SFR unit would be cheaper than 90 different fixed resistors of the same wattage.

Look at the image in post 1. The alumina substrate alone would cost more than any inventory of 90 resistors. And 90 resistors is only a true comparison if our plan to throw away 89 every time you use one normal fixed resistor. A real fair comparison is. One traditional fixed resistor vs
1 - alumna plate
4 - solderable PCB pins,
1 - High temp plastic cover
1 - stenciled or screen printing on high temp cover
1 - several solder pads (oh, look, they are on alumina - now we'll need Gallium or Indium containing solders)

Have you seen the price of gallium and indium lately?

If you know anything about manufacturing, this thing has lots of parts that makes it expensive to assemble (even if the parts are free - but they are not), expensive in terms of board space, expensive to configure, expensive to install. Also, expensive to advertise (to convince people it is not a stupid idea), expensive to train end-user designers how to take advantage of all features, expensive to train board-level assembly people how to install, expensive in how-the-hell-do-you-do-a-quality-acceptance-test-on-configurable-resistors (or find configuration errors on finished boards after these parts are installed).

Stupid idea.

 

[Ratchit]

Look at the image in post 1. The alumina substrate alone would cost more than any inventory of 90 resistors. And 90 resistors is only a true comparison if our plan to throw away 89 every time you use one normal fixed resistor. A real fair comparison is. One traditional fixed resistor vs
1 - alumna plate
4 - solderable PCB pins,
1 - High temp plastic cover
1 - stenciled or screen printing on high temp cover
1 - several solder pads (oh, look, they are on alumina - now we'll need Gallium or Indium containing solders)

Have you seen the price of gallium and indium lately?

If you know anything about manufacturing, this thing has lots of parts that makes it expensive to assemble (even if the parts are free - but they are not), expensive in terms of board space, expensive to configure, expensive to install. Also, expensive to advertise (to convince people it is not a stupid idea), expensive to train end-user designers how to take advantage of all features, expensive to train board-level assembly people how to install, expensive in how-the-hell-do-you-do-a-quality-acceptance-test-on-configurable-resistors (or find configuration errors on finished boards after these parts are installed).

Stupid idea.

A simple pulse transformer has a lot of parts and futsy assembly, too. That does not make them unusable. If SRFs make things more convenient, then they would be used. I am going to try to find out why SRF's died.

Ratch

 

[dknguyen]

A simple pulse transformer has a lot of parts and futsy assembly, too. That does not make them unusable. If SRFs make things more convenient, then they would be used. I am going to try to find out why SRF's died.

Ratch

Except there aren't a lot of simple and simpler alternatives to everything a transformer does.

 

[Ratchit]

Except there aren't a lot of simple and simpler alternatives to everything a transformer does.

A SFR offers convenience, not irreplaceability.

Ratch

 

[gophert]

A SFR offers convenience, not irreplaceability.

Ratch

If they are such a good idea, ask Bourne's for the equipment they used to manufacture these useless things. If it is sitting in some warehouse, I am sure they would be happy for you to take it and try relaunching the devices. I bet they wouldn't even ask for a royalty.

 

[ChrisP58]

A google search brought up this spec sheet. Looks like there was even a push button selectable version.
**broken link removed**

Here's the patent that covers the pushbutton version.
https://patents.google.com/patent/US3919505

The patent, as well as other references that google found, dates the product around 1974. While I see very little use to this in anything I do currently, I can't personally judge what it's comercial value to the electronics industry might have been in 1974. I was still in high school.

 

[dknguyen]

A SFR offers convenience, not irreplaceability.

Ratch

This sentence has no meaning. Irreplaceability is neither a feature nor something you offer. The so-called "convenience" you keep arguing for is specious at best. All conveniences also come at a price and that convenience must outweigh both its own price tag as well as that of any alternative. Just because something unique is being offered doesn't make it a good idea.

Weren't milkmen more convenient than running to the grocery store? They're not around anymore despite the convenience because it was outweighed by the cost.

 

[Ratchit]

If they are such a good idea, ask Bourne's for the equipment they used to manufacture these useless things. If it is sitting in some warehouse, I am sure they would be happy for you to take it and try relaunching the devices. I bet they wouldn't even ask for a royalty.

What was a good idea then might not be a good idea now.

Ratch