Component Challenge! What is this Mystery Component? - Page 1
Forum section: electronics / projects

author: TheRuler8510
author_rank: Regular Contributor
timestamp: June 05, 2014, 12:07:14 am
content: Component Challenge! What is this Mystery Component?It looks like a MOV, but I don't think it is. I'll give some clues if nobody can figure it out. It will spoil the fun if I give up too much info too quick.Regards,-----------------------------------------------------------------------

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 05, 2014, 12:28:22 am
content: If it's not a capacitor (too obvious?), maybe it's a PTC or NTC?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 05, 2014, 12:58:07 am
content: Obvious to less obvious options:MOVHV cap (I have some 10kV radial ceramics that are ridiculously thick)Resistor, esp. high energy / bulk typeNTC, e.g. inrush limitingAnything printed on the other side, or would that spoil it too?Tim

author: mrflibble
author_rank: Super Contributor
timestamp: June 05, 2014, 01:02:48 am
content: Well, first guess actually would be a MOV since it looks so movish. Second guess would be one of them inrush limiters, as in ntc.

author: TheRuler8510
author_rank: Regular Contributor
timestamp: June 05, 2014, 01:08:36 am
content: It is not a cap. There is nothing printed on the other side.It reads 9 ohms, so it does not figure with the "0013" that is printed. It is undamaged (I think).It comes from a power supply, and is in series with mains power. It seems like a waste to have 9 ohms there.Thanks,

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 05, 2014, 01:12:51 am
content: Quote from: TheRuler8510 on June 05, 2014, 01:08:36 amOnly seems like a waste at room temperature

author: fluxcapacitor
author_rank: Frequent Contributor
timestamp: June 05, 2014, 01:17:45 am
content: It looks like a resettable fuse .

author: tom66
author_rank: Super Contributor
timestamp: June 05, 2014, 02:03:09 am
content: NTC. It limits inrush from the empty bulk capacitors charging.It's 9 ohms at 25°C, which means peak current at 230V (325Vpk) is 36 ampsCompared to 100+ amps without an NTC, which can pop breakers, fuses, and damage bridge rectifiers.Once the NTC warms up its resistance drops to a low figure so it does not waste much power.

author: TheRuler8510
author_rank: Regular Contributor
timestamp: June 05, 2014, 02:41:25 am
content: Ah-ha, thanks guys--it makes total sense. I had not heard of an "NTC" before.Regards,

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 05, 2014, 02:54:16 am
content: The NTCs I usually come across are in dull green packages. A shiny blue one is new to me. MOVs often come in shiny blue, while PTCs often come in shiny yellow.If it was in series with the input, it's most likely a NTC. I have, however, come across an oddball design (in an old TV) that had a 10 ohm (at room temperature) PTC with a relay bypassing it. My guess is they decided to reduce the part inventory since another PTC was used in the degauss circuit. The relay was two pole with one doing the bypass and the other energizing the degauss circuit.

author: tautech
author_rank: Super Contributor
timestamp: June 05, 2014, 03:27:06 am
content: Quote from: TheRuler8510 on June 05, 2014, 02:41:25 amNegativeTemperatureCoefficient Thermistor

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 05, 2014, 10:59:57 am
content: Okay so... just saying...Quote from: TheRuler8510 on June 05, 2014, 12:07:14 amQuoteFor it to be a challenge... one presumes the challengeralready knows the answer, and therefore can verify that the challenge has been answered correctly...

author: TheRuler8510
author_rank: Regular Contributor
timestamp: June 05, 2014, 12:00:51 pm
content: Quote from: T3sl4co1l on June 05, 2014, 10:59:57 amGood Point...