What component is this? - Page 1
Forum section: electronics / general

author: mvno_subscriber
author_rank: Regular Contributor
timestamp: November 06, 2024, 12:30:16 pm
content: I found these components the other day while looking for NTC thermistors. I grabbed a couple since the shape was similar, and thought maybe the bars indicated resistance at room temperature.However, both of them act as an open circuit - no connection between the legs. Capacitor tester reports 0nF.Anyone know what these are? The discs are a little less wide than my thumb.

author: pcprogrammer
author_rank: Super Contributor
timestamp: November 06, 2024, 12:57:24 pm
content: I think they are capacitors. The left one 36pF and the right one either 360pF or 3.6nF, but since your tester reports 0nF it is 360pF, assuming your tester does not measure these low values.This based on what the following site shows.https://www.electronics-tutorials.ws/capacitor/cap_5.html

author: PA0PBZ
author_rank: Super Contributor
timestamp: November 06, 2024, 03:20:58 pm
content: It really doesn't look like any capacitor I've ever seen, so if they are not NTC's my guess would be varistors (VDR's) so you would need a high voltage to get it to react.Edit: look at this:https://www.ebay.co.uk/itm/402363750824Edit 2: VDR Color code:https://frank.pocnet.net/other/Philips/ColourCodeRC1966.pdfNot your colors but maybe different manufacturer/series.

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 06, 2024, 08:04:52 pm
content: Yes I would also say these are varistors.

author: mvno_subscriber
author_rank: Regular Contributor
timestamp: November 07, 2024, 08:58:42 am
content: Thanks! Yes, that seems to match. Tried to measure pF capacitance, got 50-70pF so that rules out it being a capacitor (at least based on the color codes).Wondering what interesting projects I could use these in

author: tigrr
author_rank: Contributor
timestamp: December 02, 2024, 11:35:35 am
content: Quote from: mvno_subscriber on November 06, 2024, 12:30:16 pmEven by their appearance it is clear that these are varistors. Typical for old-type varistor housings, a disk with a rough surface and soldered terminals to the center. Again, all varistors are "quite thick".

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: December 02, 2024, 12:35:57 pm
content: Quote from: tigrr on December 02, 2024, 11:35:35 am... and have some residual/parasitic capacitance.I would also say that the pictured parts are rather VDR'sI measured two VDRs found in the scrap drawer (aka 'mixed parts repository') :250 VAC VDR white (maybe Epcos) : 410 pF60 VAC VDR S&H : 1nF

author: tigrr
author_rank: Contributor
timestamp: December 02, 2024, 01:05:44 pm
content: Quote from: tigrr on December 02, 2024, 11:35:35 amI can't find their color code marking yet...

author: tigrr
author_rank: Contributor
timestamp: December 02, 2024, 01:56:32 pm
content: Here is another example of an old VDR from one of the auctions, they also have color code marking. The color of the stripes is orange, black, brown.

author: tigrr
author_rank: Contributor
timestamp: December 02, 2024, 02:02:34 pm
content: Quote from: timeandfrequency on December 02, 2024, 12:35:57 pm410 pFand1 nF- these are quite large capacitance values ​​compared to the example above.

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: December 02, 2024, 02:43:43 pm
content: Quote from: tigrr on December 02, 2024, 02:02:34 pmIt is certainly manufacturer and technology dependant.Best verification might be performed if you could have access to a semiconductor analyser (something like aTektronix 576or 577, or similar TE)

author: PwrElectronics
author_rank: Regular Contributor
timestamp: December 03, 2024, 08:43:12 pm
content: Was going to say this, varistors.We used to use these for transient protection at my company. Most commonly for clamping against load dump on 12v automotive power inputs but the ones we used were just marked with the p/n and voltage rather than color codes. Also have seen them used on 120/240V AC power inputs for spike clamping, etc.

author: tigrr
author_rank: Contributor
timestamp: December 03, 2024, 09:07:26 pm
content: Quote from: mvno_subscriber on November 06, 2024, 12:30:16 pmHere's what I found on the color code marking ofVDRandNTC. This is thePhilipsmarking of the1966standard. VDR in the upper left corner, NTC in the right.But! It is not yet entirely clear how to decipher the varistor ratings using the tables. And, this especially concerns the second black and white table... What color codes are meant there? If anyone knows, please write!