Fake diode bridge - Page 1
Forum section: electronics / beginners

author: Olegkuskhov
author_rank: Contributor
timestamp: December 31, 2024, 02:21:33 pm
content: Hi guys, just curios to ask. The entire time im using this diode type bridge, the voltage drops after load after diode bridge and after the filter capacitor is huge.For 1 A off current the voltage drop is 2 voltI notice that the bridge is hot although it is advertised to be 35 A 1000 V bridge.Tired of the result, i try to crushed it and found the silicon die to be this small. I've seen much bigger die but in transistor that i belive only rated for 10 A.Is this diode bridge fake?.I place pliers next to it so you guys can imagine the size of it.

author: CaptDon
author_rank: Super Contributor
timestamp: December 31, 2024, 02:43:59 pm
content: What a joke. A bridge with wire leads like that would be maybe 6 to 10 amps continuous with perhaps a 35 amp non-repetitive peak rating. The 'real' 35 amp sustained world would have spade terminals or some sort of clamping like a screw terminal. That thing looks like a 3 amp 200 volt kind of bridge.

author: wraper
author_rank: Unknown
timestamp: December 31, 2024, 02:59:58 pm
content: First of all what actual part number? Secondly, for 35A you need a heatsink regardless of what part you use. Not to say for a part like this you already need heatsink above 5-10% of rated current. Side cutter for scale makes no sense as they vary in size a lot.QuoteAnd what did you expect?Quote from: CaptDon on December 31, 2024, 02:43:59 pmIf you think about thin leads lying around, it seems there are 2 different rectifiers on the picture with thin lead part on the right side.

author: RoGeorge
author_rank: Super Contributor
timestamp: December 31, 2024, 03:02:36 pm
content: - 1V per diode, so 2V per bridge is not unusual- I guess the 35A is the max repetitive peak current the bridge can withstand, and not the continuous RMS. Add the part number and the datasheet, to see what is the 35A referring to- same for heating, it is normal for a bridge to heat under 1A, the datasheet will tell by how much

author: wraper
author_rank: Unknown
timestamp: December 31, 2024, 03:09:57 pm
content: Quote from: RoGeorge on December 31, 2024, 03:02:36 pmWhy, 35A peak repetitive would be some small rectifiers. This one looks to be something like thishttps://www.mouser.com/datasheet/2/1057/GBJ3510-2949762.pdf

author: CaptDon
author_rank: Super Contributor
timestamp: December 31, 2024, 03:16:27 pm
content: Well Wraper, What would you estimate looking at that bridge?Sure as hell isn't 35 amp continuous rated with leads like that. I am very sad that I "don't know components" since I have been a design engineer for over 45 years since a time when we were replacing selenium bridge rectifiers with silicon bridge rectifiers that looked like a multi plate selenium bridge with little top hat style diodes pressed into the fins. I can't guess the voltage rating of that bridge pictured but I can damn sure get a ballpark figure on what amount of current it may safely pass by its construction. 20 amp and up bridges don't generally look like that one! A 35 amp rated bridge would probably include a mounting hole for heatsink mounting as well as one surface being metallic or ceramic substrate to mate with the heatsink.

author: RoGeorge
author_rank: Super Contributor
timestamp: December 31, 2024, 03:18:22 pm
content: Quote from: wraper on December 31, 2024, 03:09:57 pmCould be, but it looks bigger than the crashed one, and for 35A it has to be put on a radiator. Without radiator can withstand only 3A. The crashed one doesn't have a hole to fix it on a radiator. Anyway, without the part number and the datasheet of the crashed bridge we can not be sure.

author: wraper
author_rank: Unknown
timestamp: December 31, 2024, 03:32:25 pm
content: Quote from: CaptDon on December 31, 2024, 03:16:27 pmI edited it before you posted. If you think about leads lying around, it seems bits of 2 different rectifiers are lying around. Part with silicon die is certainly rated for more than a few amps.QuoteThere are signs of the mounting hole. And nope for the latterhttps://www.lcsc.com/product-detail/Bridge-Rectifiers_Diodes-Incorporated-GBJ3510-F_C705327.htmlQuoteThat would be for a tiny 1A rectifier like thishttps://eu.mouser.com/datasheet/2/345/db101_db107-1774120.pdf

author: SteveThackery
author_rank: Super Contributor
timestamp: January 01, 2025, 02:54:37 pm
content: I wonder if the OP has disappeared. If not, it would be helpful to know the exact markings on the device. "35A" isn't meaningful on its own: it could be peak or it could be continuous. If it's a peak rating, then the physical size of the die might be about right.Please give us the device markings.

author: schmitt trigger
author_rank: Super Contributor
timestamp: January 01, 2025, 03:20:51 pm
content: Exactly, post the part numbers or at least a focused, close up photo of the device before nuking it.