Fluke 742 resistor hardware clone ? any interest ? - Page 1
Forum section: electronics / general

author: Overspeed
author_rank: Frequent Contributor
timestamp: December 07, 2024, 10:53:12 am
content: HelloI plan to manufacture CNC enclosure base on the 742 design so :Main enclosureLead enclosure drilled for 4 mm post ( will be designed to allow opening to BNC )Foam insulationCopper bladeInternal blades support in Perplex / PEHD1000 ??S304 screws setlet me know your feed backRegardsOS

author: Dr. Frank
author_rank: Super Contributor
timestamp: December 07, 2024, 11:06:51 am
content: That's interesting.I suggest to add a precision temperature sensor, and a feature to thermally couple the resistors, because that is a design flaw of the Fluke 742A, and the WEKOMM RS9010A, compared to the SR104.

author: Overspeed
author_rank: Frequent Contributor
timestamp: December 07, 2024, 11:33:24 am
content: Quote from: Dr. Frank on December 07, 2024, 11:06:51 amHelloYes I have planed to install a Pt100 sensor well through the front panelRegardsOS

author: maat
author_rank: Regular Contributor
timestamp: December 07, 2024, 11:57:15 am
content: Are you interested in open source the design files?If so, I would be interested in manufactured units as well.

author: Overspeed
author_rank: Frequent Contributor
timestamp: December 07, 2024, 02:05:02 pm
content: HelloYes perhaps asap I have supply my own need and make some tests , take in considerations that request CNC machining or at least time and manual milling machine , as all ''electronic guys '' have this equipment.I use slice cut of square 100 mm x 100 mm 6061 extruded tube to avoid machining from a block of light alloy and keep the price low as possibleThat a front and back lead enclosure so that allow to pour the enclosure with insulation balls if needed or even to use the enclosure both faces to avoid the need of two enclosures for two different refs as 10 K and 100 K for example .RegardsOS

author: MiDi
author_rank: Frequent Contributor
timestamp: December 07, 2024, 03:25:36 pm
content: Alternative to manufacture from scratch e.g.https://de.aliexpress.com/item/32884407649.html

author: Mickle T.
author_rank: Frequent Contributor
timestamp: December 07, 2024, 07:49:34 pm
content: When I made the Fluke 742 clone, I used a silumin Gainta electrical enclosure with a thermally and electrically insulated inner copper case.

author: Overspeed
author_rank: Frequent Contributor
timestamp: December 07, 2024, 08:03:08 pm
content: Quote from: MiDi on December 07, 2024, 03:25:36 pmHelloYes but that thin aluminium and also not really easy to install the copper rails , can be a solution for simple foil resistor , I need to use parallel resistors with robust setup .RegardsOS

author: Overspeed
author_rank: Frequent Contributor
timestamp: December 07, 2024, 08:09:12 pm
content: Quote from: Mickle T. on December 07, 2024, 07:49:34 pmHelloNice setup , I like the ceramic castle slotted rest with the copper linkI have some extruded square tube in aluminium I have designed lead look a like Fluke 742 with a temperature well made in a SS304 bolt blind drilled , to keep the price low as possible .RegardsOS

author: laichh
author_rank: Regular Contributor
timestamp: December 09, 2024, 03:05:22 am
content: There are some pretty decent off-the-shelf aluminum enclosure to choose from. Personally I would go for ROSE Enclosure Aluform series 040808080 (80*80*81 mm), or 041212080 (120*120*81 mm) if the size does matter.https://www.rose-systemtechnik.com/en/rose-products/040808080/https://www.rose-systemtechnik.com/en/rose-products/041212080/

author: aronake
author_rank: Frequent Contributor
timestamp: December 09, 2024, 09:59:12 am
content: Someone in China has allready made "Fluke 742 inspired" boxes and sell these.One way forward could be that instead of making something that look like a 742 box, critically think (and maybe experiment) how a box can be made better. Good arrangements for thermal coupling and temperature measurements as mentioned here. Good arrangements for mounting or soldering resistors. Maybe some thermal insulation.

author: Overspeed
author_rank: Frequent Contributor
timestamp: December 09, 2024, 01:38:16 pm
content: Quote from: aronake on December 09, 2024, 09:59:12 amHelloImpressive including the front label .... Question : do you know the price as my Chinese speaking and reading is quite poorRegarding how the box can be good yes , as that possible to include shielding ( double metal skin outside in aluminium alloy internal in copper nickel plated or even steel nickel plated ? ) and thermal insulation and a temp sensor wellSee Zlymex DIY resistor boxhttps://www.eevblog.com/forum/metrology/teardown-standard-resistors/25/RegardsOS

author: laichh
author_rank: Regular Contributor
timestamp: December 10, 2024, 02:31:02 am
content: My approach, the enclosure is Hammond R196-082-000, the two side plastic covers were broken by accident.

author: aronake
author_rank: Frequent Contributor
timestamp: December 10, 2024, 12:17:39 pm
content: Quote from: Overspeed on December 09, 2024, 01:38:16 pmThis is from a Chinese app called Xianyu. Main purpose of the app is for private people to sell used things. Seems there are some volt-nuts selling all sorts of interesting things there as well. It seems to me that a chinese phonenumber is needed to register as a user, and I have not figured out how to sort that out yet.

author: zrq
author_rank: Frequent Contributor
timestamp: December 15, 2024, 04:09:27 pm
content: Quote from: Overspeed on December 09, 2024, 01:38:16 pmJust checked that out in Xianyu, the price is 5555 CNY and the seller said lower offers are not considered. Probably not worth it.

author: shenxiaoming
author_rank: Newbie
timestamp: December 19, 2024, 02:12:24 pm
content: 5555 cny contains four Fluke resistors.

author: ddrl46
author_rank: Regular Contributor
timestamp: December 19, 2024, 03:35:11 pm
content: How did you make those front panel labels? Did you make them yourself or have them manufactured?

author: Overspeed
author_rank: Frequent Contributor
timestamp: December 19, 2024, 03:39:29 pm
content: HelloNo , front panel label can be ordered bespoke made from sticker companies if you send the CAD file , price is very reasonable if you order per 10 or morePrinter have cutter so they can cut hole all around the postsRegardsOS

author: Overspeed
author_rank: Frequent Contributor
timestamp: January 01, 2025, 09:27:09 am
content: HelloA screen print of my 742 enclosure , as I have 150x150 mm 6082 tube I have designed twin resistor value enclosure to group 0.1 and 1 Ohm or use two same value side by side one very low tempco and one other ''general purpose'' a lower cost or with higher current valueThere is one central temp sensor well .the box is set to add four post in a raw to use the the resistors as dividerfront milled pockets are made to install stickers not flush so protectedInternal is a clone a the Fluke 724 with PTFE support on aluminium plate , perhaps SS304 as I want to avoid aluminium conversion surface treatment as alodine to keep price low.RegardsOS

author: Overspeed
author_rank: Frequent Contributor
timestamp: January 02, 2025, 03:34:27 pm
content: HelloProgress . the rear lidI plan to use polystyrene ball as insulationRegardsOS

author: mendip_discovery
author_rank: Super Contributor
timestamp: January 02, 2025, 07:59:12 pm
content: does that not cause static electricity?

author: Overspeed
author_rank: Frequent Contributor
timestamp: January 02, 2025, 09:39:59 pm
content: Quote from: mendip_discovery on January 02, 2025, 07:59:12 pmHelloyes ,but antistatic polystyrene existhttps://productpackagingsupplies.com/Category/Anti-Static-Polystyrene-Packing-Peanutsother method is to increase thermal inertia by using block of metal all around the resistors . zlymex on this forum have a different assessment I link a screen-printRegardsOS

author: Overspeed
author_rank: Frequent Contributor
timestamp: January 04, 2025, 03:44:49 pm
content: HelloAs technical solution I go with a clone of IET solution ,that allow a wide range of setup and drilling is easy even with a hand drill.I link two pictures from Zlymex forum memberRegardsOS

author: fisherman1999
author_rank: Newbie
timestamp: January 13, 2025, 05:32:27 am
content: I thank "hardware clone " shouldn't be "brand clone"

author: Overspeed
author_rank: Frequent Contributor
timestamp: January 13, 2025, 10:12:03 am
content: Quote from: fisherman1999 on January 13, 2025, 05:32:27 amHelloI have tried to make some improvements I think that double set side by side is interesting for personal use / small lab as I can use ''working resistor '' side by side with my resistor standard in the same enclosure OR use the 4 additional banana posts ( not drilled but center drill ) to built a divider OR .... but save room and moneyCost or a double enclosure is not really higher than a single unit.I don t want to challenge Fluke but I am not ready to pay thousands of Euro in a standard resistor .Xdev have succeed built valuable standard resistor by using surplus resistors .RegardsOS

author: aronake
author_rank: Frequent Contributor
timestamp: January 20, 2025, 05:22:04 am
content: Here is someone who have done something similar.https://www.ebay.com/itm/205234014314?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=cazmjidtttq&sssrc=2047675&ssuid=A39wMAAfQHS&var=505985273668&widget_ver=artemis&media=COPYThe two types of terminal used are very recognizable. I would think the designer of these is present here in the metrology section of eevblog forum.

author: Overspeed
author_rank: Frequent Contributor
timestamp: January 20, 2025, 06:18:48 am
content: Quote from: aronake on January 20, 2025, 05:22:04 amHelloNice looking unitKey FeaturesRS-3 Ultra Low Drift & TCRDouble Hermetically Sealed in Silicone Fluid.Specially aged and TCR-matched 10 resistor array providing the lowest possible TCR and drift with cutting-edge resistor technology.TCR < 0.5 ppm/C 15°C to 30°C.1 Year Drift < 2.5 ppm/yr.Includes Temperature characterization and Calibration certificate.RS-7 Low Drift, Low TCRSingle Hermetically Sealed in Argon.Specially aged 3 resistor array providing low TCR and drift.TCR < 2.5 ppm/C 15°C to 30°C.1 Year Drift < 4 ppm/yr.Includes Temperature characterization and Calibration certificate.sound interestingRegardsOS

author: manganin
author_rank: Regular Contributor
timestamp: January 20, 2025, 07:56:50 am
content: Quote from: fisherman1999 on January 13, 2025, 05:32:27 amExactly.It is just a matter of time when the clones end up for sale in Ebay. And later get sent for calibration to the Fluke lab...

author: aronake
author_rank: Frequent Contributor
timestamp: January 20, 2025, 09:17:21 am
content: Quote from: manganin on January 20, 2025, 07:56:50 amyes, too nice and talented work to print Fluke on it.

author: Overspeed
author_rank: Frequent Contributor
timestamp: January 20, 2025, 09:54:00 am
content: HelloI have modified the design to avoid any ''illegal'' copy claim , my goal is to built useful equipment / affordable and more specifically to allow bespoke low value resistor.RegardsOS

author: Overspeed
author_rank: Frequent Contributor
timestamp: January 21, 2025, 06:55:48 am
content: HelloI link a 3D pic of the exploded viewRegardsOS

author: manganin
author_rank: Regular Contributor
timestamp: January 22, 2025, 01:19:40 pm
content: How about a simple sealed diecast aluminium enclosure?That is what Guildline and Mintl use nowadays.Not as pretty as those profile boxes, but provides an extra layer of protection for free.Close enough to hermetic, if you rubber or epoxy seal the binding posts.

author: Overspeed
author_rank: Frequent Contributor
timestamp: January 22, 2025, 04:52:07 pm
content: Quote from: manganin on January 22, 2025, 01:19:40 pmHelloI want to keep the internal Fluke design with the plate and the possibility to handle all the parts with the front panel so an easy assembly and wiring , I want also to group two resistor value in the same enclosure ( with the option to wiring them as a divider , that why the front panel can handle 4 more banana posts )Rear panel can be opened to install thermal insulationYes for simple unit that possible to use commercial enclosure if the quality is good and not cheap cast aluminiumRegardsOS