Source of useful thermal imaging plastic sheeting is LCRHallcrest - Page 1
Forum section: electronics / general

author: cdev
author_rank: Super Contributor
timestamp: February 04, 2019, 08:25:52 pm
content: A number of times I've raved on here about how useful its been to have "LCR" (liquid crystal based) "thermochromic" plastic sheets around for use in troubleshooting.Its almost an understatement to just use the word useful, as it can be used just like an expensive thermal imaging camera to detect shorts and small gradations in heat on a PCB. Invaluable would be more appropriate.It can allow devices to be fixed that are difficult to troubleshoot any other way.its non-invasive visual troubleshooting showing what is heating up is a major time saver.To use it its about as simple as can be, however, I think the most useful way to use it is with a current limited supply. When a device has an internal problem -you dont want to create any more damage, by applying full power, but you still want to figure out where the abnormal power usage is.What I do is use it I energize a device with a lower voltage while I set the current limit much lower than its expected draw but high enough to generate some heat, then if I dont see where the heat is, I raise the voltage a bit until I can visualize where the energy is going but with the current limiting set to trigger fairly low, not high enough to allow damage. You'll have to pick a good value based on what you know about the current draw normally.Anyway, the company that makes this thermochromic material is LCRHallcrest, they are a scientific company that sells their products to a wide variety of companies, their web site ishttp://hallcrest.comand they have two offices, one in the US and one in the UK.LCR Hallcrest LLC - US1911 Pickwick Lane - Glenview, IL 60026847.998.8580sales@hallcrest.comcustomerservice@hallcrest.cominfo@hallcrest.comTheir international address and phone number issalesuk@hallcrest.com+44 (0)1244817107LCR Hallcrest Ltd – UKRiverside BuildingsDock RoadConnah's QuayFlintshireCH5 4DS+44 (0) 1244 817107salesuk@hallcrest.comThe sheeting flavors that I have personally found to be the most useful are R20C5W (20-25 degrees C) and R25C5W (25-30 degrees C) they have higher and lower temperatures too. It would be useful to have a wider range. Depending on your troubleshooting style.They claim they have a limited shelf life but in my experience they last quite a long time if kept in a binder when not in use, and if you only use them briefly, to find whats hot.They are most useful to have for troubleshooting anything thats malfunctioning either where there is a short OR when you have one working and one nonworking unit, by comparison. That covers a lot of use cases."Almost everything"I have "a number" of items here at home which are good candidates for a demo repair. When I have a bit of time to do that, hopefully today or tomorrow, I will add some images to this thread.If anybody from Hallcrest reads this, you really should make a small, low cost package of a few sheets, specifically aimed at people like us. Price it cheaply but high enough to cover your cost of mailing and add a web page to your site briefly explaining how useful they are in troubleshooting for both electronics hobbyists and pros, especially when used with a bench power supply with both adjustable voltage and current limiting capability.I'm sure there are many other applications in electronics as well.

author: Fraser
author_rank: Super Contributor
timestamp: February 04, 2019, 09:48:10 pm
content: In the UK, mine came from this company.....https://www.sfxc.co.uk/products/lc-liquid-crystal-thermochromic-sheetsIIRC I got it cheaper via eBay. I will check.FraserUpdate: the auction for my Thermochromic sheet is herehttps://www.ebay.co.uk/itm/Liquid-Crystal-Thermochromic-Thermocolour-Sheet-35C-to-36C-150mm-by-150mm/231769563934?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649Less than £9 including postage for a sheet and there were other temperature ranges available. I chose the most sensitive sheet for some tests. Sadly it looks to be out of stock but it may be worth contacting the seller as my sheet came from SFXC so this eBay seller may be their outlet.Fraser