LVDT sensors unusually expensive - Page 1
Forum section: electronics / general

author: ace1903
author_rank: Regular Contributor
timestamp: April 25, 2017, 07:04:13 am
content: Hi,Couple of years ago I made LVDT senor in DIY style. It wasn't perfect but it worked well.Now when I am looking on e-bay to buy one it seems that price range starts from 150$.For me, that it is expensive for ~100g magnetic wire and ~100g stainless steel. There are a lot of products that contain more copper, stainless steel and machining hours and again are less expensive than 50$.Even digital calipers(not know exact name for that tool that are used in metalworking and looks like watch) with equal precision are in range 30$.When prices are high for me that is indication of patent holding trolls.Does anyone knows whats makes LVDT expensive? Does someone have video or pictures form teardown of some device?I know that they are not common in the industry and well known brands with good reputation dictate price (added price due to reliability and good history).But what stops some manufacturer in China to make them and sell for lot less?

author: ebclr
author_rank: Super Contributor
timestamp: April 25, 2017, 08:58:20 am
content: Try to buy a vacuum tube in now days will be very expensive alsoTake a look on 21 century linear sensorhttp://ams.com/eng/Products/Magnetic-Position-Sensors/Linear-Position/AS5311

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 25, 2017, 09:19:34 am
content: They aren't made in vast quantity, so don't have much cost reduction; but more importantly, you're paying for whatever paperwork follows them. LVDTs are common in aerospace applications.Tim

author: S185149
author_rank: Contributor
timestamp: October 10, 2017, 04:50:24 am
content: Quote from: ace1903 on April 25, 2017, 07:04:13 amI am interested in how you built your LVDT. Could you explain please?

author: Old Don
author_rank: Regular Contributor
timestamp: October 10, 2017, 01:39:32 pm
content: We used to use a lot of LVDT's in industrial products because they were non contacting and therefore won't wear out during use. Today, there's optical sensors and other transducers that are cheaper, I'd guess. So I would hazard a guess that the market for LVTD's has shrunk and any on the market are dregs of prior production. If there was a market then they'd be cheap as chips. More or less like I don't know when I last saw a magnetic amplifier being used. Or a new floppy drive design for that matter! Yikes, I'm starting to feel obsolete myself.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 10, 2017, 04:35:39 pm
content: Quote from: Old Don on October 10, 2017, 01:39:32 pmThe market's big, and they're still just as cheap as chips -- for the same market sector, military and aerospace.Tim

author: thm_w
author_rank: Super Contributor
timestamp: October 10, 2017, 09:43:14 pm
content: It looks like resistance based sensors are cheap:https://www.aliexpress.com/item/KTC-200mm-KTC-200-rod-electronic-scale-linear-displacement-transducer/32754585521.htmlNot sure about lifespan though.Maybe you can post your requirements: stroke length, maximum speed, accuracy, etc.Low availability is not really an indication of patents so much as market demand.bigclive had a pressure transducer that is built down to a very low price, presumably:but getting your hands on one might not be easy.

author: S185149
author_rank: Contributor
timestamp: October 11, 2017, 02:08:51 am
content: I don't have an application in mind. I was interested in the LVDT as a learning aid. I have made coils by wrapping mag wire around non-metallic cores and they seem to work fine when detecting the magnetic field from my metal detectors. I now want to see what it takes to couple two coils.Thanks,S18