What does the color scheme on this capacitor mean? - Page 1
Forum section: electronics / projects

author: Ben321
author_rank: Frequent Contributor
timestamp: February 12, 2024, 08:23:05 pm
content: I noticed this high voltage module has an electrolytic capacitor on the input, which makes sense because the device uses a high frequency oscillator to generate the high voltage, and the capacitor keeps the high frequency signal from the oscillator from leaking back onto the power wires (which could then radiate and cause RF interference). But what does the green color of the capacitor mean? Does that mean it has a low inductance? I've heard of certain capacitors for high frequency applications that have low inductance, but these are also usually lower capacitance capacitors (like 1uF or less), and they usually aren't electrolytic. But this is an electrolytic capacitor with 100uF capacitance, and it has an unusual color scheme. So I was wondering if the green color here (as well as the gold colored writing on the capacitor) is a color code for being a low inductance high capacitance electrolytic capacitor? If so it would indeed be pretty rare, as I can't find anything on Google regarding low inductance electrolytic capacitors (something I looked up, because I suspected that this might be such a capacitor).Here's a picture of the high voltage module.https://i.ebayimg.com/images/g/nA8AAOSw4gJc65Wi/s-l1600.webpNow this is important to know, because I'm going to have to buy one of these capacitors. I bought the high voltage module (not the one from eBay, but one that's even cheaper from AliExpress), and it doesn't have the power input capacitor. Instead, there's a blank place on the circuit board to solder your own. So I'm going to need to buy one of these capacitors, and I want to make sure I'm buying the correct type.

author: tggzzz
author_rank: Super Contributor
timestamp: February 12, 2024, 08:38:55 pm
content: Quote from: Ben321 on February 12, 2024, 08:23:05 pmThe colour means nothing significant.Important features: voltage, ripple current, operating frequency (100Hz or >10kHz), temperature, lifetime. Deduce those from looking at the capacitor's manufacturer and markings indicating the manufacturer's type.Good replacement brands: Nichicon, Panasonic, Rubycon, Vishay, Wurth.

author: Ian.M
author_rank: Super Contributor
timestamp: February 12, 2024, 08:46:09 pm
content: +1The color scheme of the wrap on electrolytic capacitor cans means precisely *nothing*. A manufacturer chooses a base and ink color to suit their branding and maybe visually differentiate product ranges, then the usual far east cloners copy it on inferior parts.However the only downside of using a low ESR 105° C part to replace an ordinary electrolytic on the supply input would be a slightly higher inrush current when power is first connected. Find one the right voltage and value and same can size from a reputable supplier, fit it and stop worrying!

author: floobydust
author_rank: Super Contributor
timestamp: February 12, 2024, 09:05:23 pm
content: The green coloured caps are low ESR electrolytics, as far as china is concerned. Ordinary electrolytics are black, again as far as china is concerned.Interesting to note that OP's board has an Ethernet LAN transformer H1106NL (it appears to provide gate-drive), as well as the usual "15kV" igniter transformer.The microcontroller STC 16W101 no data. Very clever cost savings.

author: Ben321
author_rank: Frequent Contributor
timestamp: February 12, 2024, 09:57:33 pm
content: Quote from: floobydust on February 12, 2024, 09:05:23 pmWhat does ESR stand for? Also, the brand of electrolytic capacitor used on the eBay version of this appears to be from a Chinese company called Thangxin (going by the name in the logo on the capacitor). Any idea if that's a reputable company?By the way, the board on the eBay one is slightly different too, compared to the one I bought on AliExpress. Not only is the AliExpress one missing the input capacitor, it also uses different components (though overall has the same appearance, and seems to be designed as a high frequency high voltage AC output module). There's quite a few more components on the AliExpress version, and none of them are through-hole components (with the exception of the capacitor solder points and the output transformer, and 5 solder points for test wires to be soldered in place at the factory but have nothing soldered to them when shipped out). On the eBay version, there's 3 power transistors and all of them are through-hole. On the AliExpress version, there's only one power transistor, and it's surface mount.Here's a picture (taken from the website) of the AliExpress one that I actually bought.https://ae01.alicdn.com/kf/S9acf707591964fc28fdeaa4ae9797044K/DC-7V-15V-12V-To-15KV-20KV-High-Frequency-AC-High-Voltage-Generator-Inverter-Boost-Spark.jpg_.webp

author: tggzzz
author_rank: Super Contributor
timestamp: February 12, 2024, 10:09:41 pm
content: Quote from: Ben321 on February 12, 2024, 09:57:33 pmSee the first reference athttps://duckduckgo.com/?q=capacitor+esr