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Author Topic: brain storm an optimal human safety system for back line  (Read 102445 times)

Mark Cadwallader

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Re: brain storm an optimal human safety system for back line
« Reply #400 on: November 19, 2015, 01:35:52 am »

Reasonable is a relative term for whatever value is derived from ownership and use.  I see this as a teaching tool that has great practical value and I'd be willing to spend a bit more, perhaps, because of the dual purpose.

How much?  Not sure yet, but I think the home inspector guys would snap these up at $30 - $40.

The market for this device is much greater than our little world.


Given an internet price of $12 to $20 for a hospital grade right angle 5-15p device, that $30 to $40 price seems like a pretty fair guess, when produced in quantities that would be sold to the electrical and construction trades.  At more than $50, I would probably hesitate to buy one (as a non-construction industry guy).  NCVTs seem to sell in the $9 to $40 range (depending on brand and quality) at stores in my area, so $30 to $40 seems like a very reasonable price to me.

Please note that I have no inside knowledge of JR's UCT device, and I would not presume to speak for JR. I am a beta tester, but I have no financial interest in the product.
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John Roberts {JR}

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Re: brain storm an optimal human safety system for back line
« Reply #401 on: November 19, 2015, 10:01:55 am »


Given an internet price of $12 to $20 for a hospital grade right angle 5-15p device, that $30 to $40 price seems like a pretty fair guess, when produced in quantities that would be sold to the electrical and construction trades.  At more than $50, I would probably hesitate to buy one (as a non-construction industry guy).  NCVTs seem to sell in the $9 to $40 range (depending on brand and quality) at stores in my area, so $30 to $40 seems like a very reasonable price to me.

Please note that I have no inside knowledge of JR's UCT device, and I would not presume to speak for JR. I am a beta tester, but I have no financial interest in the product.

I have no idea what the price will be... In fact I really don't want to start another business (I'm old and tired), but this is too important not to do, IMO.

The company I thought was ideal to partner with apparently isn't interested. So I am bringing the design forward myself. Maybe later it will be easier to get a partner after I do more ground work.

Regarding cost, right now that fancy plug looks like the most expensive component, but I haven't investigated quantity pricing yet, hopefully I don't have to pay onsey-twosey price markups. I don't need hospital grade so there may be some cost savings available. 

The circuitry is not very expensive... I'm looking at using a higher voltage MOFSFET since I have already lost one in beta testing but that may be a fluke. Even with higher voltage mosfet the parts BOM is not too bad... but there is a bunch of parts, over 20 pops in the current version, so machine time may equal parts cost for the several resistors and diodes that are only pennies in production quantity.

Since you can't get a contract manufacturer to turn on their machines for less than a few hundred pieces, even this cheap BOM will add up. Most small parts will be bought on 5,000 piece reels. 

Using a stock off the shelf plug housing will save me some NRE for not having to tool up the plug housing (not trivial or cheap), I will still have the NRE for agency approval. I already spent $400 for the UL spec describing the current outlet tester... When I feel confident I can pass, I need to submit something like 9 units for them to test (which won't be cheap). In fact three of the nine units are for testing associated with the plug, so using an already UL listed component may allow me to forgo that mechanical plug specific testing. 

I have decided not to pursue a patent (already have that wall papered), which means if this is successful, I need to make hay before the competition copies it and under cuts me.

It is premature for me to even think about a firm price, I know that this is never going to compete with the $5 outlet testers (that don't work). My parts will cost me more than that.

I already have enough beer money to drink myself to death, so mainly want to get my capital investment back from this. I expect I am just now starting to spend real money. I actually enjoy the design part of this... This week I am learning about how MOSFETs fail, building stuff not so much fun, selling it even less. 

JR
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Merlijn van Veen

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Re: brain storm an optimal human safety system for back line
« Reply #402 on: November 19, 2015, 11:16:42 am »

Great developments. Happy to read your pushing forward. Does this technology also apply to the EU?

John Roberts {JR}

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Re: brain storm an optimal human safety system for back line
« Reply #403 on: November 19, 2015, 11:40:13 am »

Great developments. Happy to read your pushing forward. Does this technology also apply to the EU?

The general technology concept of using the human touch probe as the local 0V reference would work, but the diodes and MOSFET and resistor values would all need to be different, not to mention a different physical plug housing.

I am already looking at perhaps scaling up to a 400V mosfet (that could handle 230VAC) but I'm only using 300V diodes that can't handle 230VAC.

Yes a version could be made, but no I am not pursuing one at this time.

JR
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Merlijn van Veen

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Re: brain storm an optimal human safety system for back line
« Reply #404 on: November 19, 2015, 11:50:55 am »

Thanks for replying and good to know.

Jonathan Johnson

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Re: brain storm an optimal human safety system for back line
« Reply #405 on: November 19, 2015, 12:43:54 pm »

I am already looking at perhaps scaling up to a 400V mosfet (that could handle 230VAC) but I'm only using 300V diodes that can't handle 230VAC.

I think that designing for 250V is a very good idea, as someone may have wired a NEMA 5-15R or 5-20R receptacle for 240V (in violation of code). I think it was Mr. Sokol that had personal experience with this...  :o

Which means that your tester might need to identify such a beast as incorrectly wired!
« Last Edit: November 19, 2015, 12:54:30 pm by Jonathan Johnson »
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John Roberts {JR}

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Re: brain storm an optimal human safety system for back line
« Reply #406 on: November 19, 2015, 12:54:52 pm »

I think that designing for 250V is a very good idea, as someone may have wired a NEMA 5-15R or 5-20R receptacle for 240V (in violation of code). I think it was Mr. Sokol that had personal experience with this... ;-)

Which means that your tester might need to identify such a beast as incorrectly wired!
I need to beware feature creep... For now I want to KISS and get it working robustly for the basic function (identifying mis-wired outlets).

Too much/not enough voltage is easy enough to determine with a VOM.

At some point in the future I might mess around with trying to parse ground-neutral swaps, and ground quality (impedance), but this is an order of magnitude more complex (I'd use a microprocessor), and much lower demand.

JR
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Jonathan Johnson

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Re: brain storm an optimal human safety system for back line
« Reply #407 on: November 19, 2015, 02:30:06 pm »

I need to beware feature creep... For now I want to KISS and get it working robustly for the basic function (identifying mis-wired outlets).

Too much/not enough voltage is easy enough to determine with a VOM.

At some point in the future I might mess around with trying to parse ground-neutral swaps, and ground quality (impedance), but this is an order of magnitude more complex (I'd use a microprocessor), and much lower demand.

JR

I guess I was figuring that it would somehow indicate voltage on both hot and neutral -- not necessary to parse the voltages. As for designing for 250V, what I meant was that the device would not be damaged by connecting to an outlet that's wired for 240V -- robustness. I agree with KISS.

I expect that people will plug in the "easy" thing first, and your Robert's Outlet Tester (RobOT) will be seen as easier to use than a VOM -- just like they reach for the commodity three-light outlet tester now.
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John Roberts {JR}

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Re: brain storm an optimal human safety system for back line
« Reply #408 on: November 19, 2015, 02:42:13 pm »

I guess I was figuring that it would somehow indicate voltage on both hot and neutral -- not necessary to parse the voltages. As for designing for 250V, what I meant was that the device would not be damaged by connecting to an outlet that's wired for 240V -- robustness. I agree with KISS.

I expect that people will plug in the "easy" thing first, and your Robert's Outlet Tester (RobOT) will be seen as easier to use than a VOM -- just like they reach for the commodity three-light outlet tester now.

I am going to be testing for insulation resistance with 500V, not crazy to push the technology up to 400V it's only money and size... (but people are already whining about price.  :o ).

JR

PS: Like the name (cute), while another promise to myself was never name a company after myself after seeing old obsolete Roberts tape recorders. My working name these days is OD-1 (outlet detective one), but I'll add RobOT to the short list. .
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John Roberts {JR}

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Re: brain storm an optimal human safety system for back line
« Reply #409 on: November 21, 2015, 12:13:25 pm »

I think that designing for 250V is a very good idea, as someone may have wired a NEMA 5-15R or 5-20R receptacle for 240V (in violation of code). I think it was Mr. Sokol that had personal experience with this...  :o

Which means that your tester might need to identify such a beast as incorrectly wired!

For the forum members arguing for lower price, we may need to stop suggesting new features.  ;D

I have upgraded the diodes and MOSFET to 400V technology so accidental exposure to 240VAC will not harm it, some resistors could get hot but should be fine for brief exposure.

I have scratched out a simple indicator for 240VAC mains using a neon bulb, fed from a voltage divider. I haven't tested this on the bench yet but I should be able to pad down the mains voltage enough to ignore 120VAC and indicate when 240VAC is present.

If this extra feature is not needed or wanted I can just not populate the lamp. 

Getting close to cutting this third generation PCB loose. I will need to perform testing on this 3rd generation (like 500V insulation, etc), before i yank UL's chain to open a file and begin expensive testing. There are cheaper test labs, but if I want to actually change the UL spec to reflect my improved functionality that looks like only UL can do that.

Still making good progress. After spending hundreds of dollars on parts, it seems a false economy to not air ship the prototype PCBs from China.

JR

PS: Current working names,,, OD-1 (outlet detective), and RobOT (Roberts outlet tester), ....next?
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Re: brain storm an optimal human safety system for back line
« Reply #409 on: November 21, 2015, 12:13:25 pm »


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