Need help identifying Mosfet - Page 1
Forum section: electronics / repair

author: lmagalhaes
author_rank: Contributor
timestamp: December 27, 2021, 09:30:05 am
content: Hi there,I have a nebulizer board from TDK that has a faulty mosfet. I can find similar mosfets online in Aliexpress and sites like that, but fail to get a datasheet. I'd rather get the datasheet and look for a similar mosfet that is available either on Mouser or Digikey or any other distributor. Can you guys help me identify this little mosfet ? I've searched the web and found that this guy is probably made by Sanken Semiconductors, but their datasheets are really incomplete.Here's a picture of him:And I'm betting is this one, but I wanted to make sure:https://www.semicon.sanken-ele.co.jp/ctrl/en/product/category/MOSFET/detail/?product=2SK2701AAny takers?Best regards,Luís

author: abdulbadii
author_rank: Frequent Contributor
timestamp: December 27, 2021, 12:39:03 pm
content: Device/schematic please ? To help id its property/function..

author: DavidAlfa
author_rank: Super Contributor
timestamp: December 27, 2021, 04:04:23 pm
content: Here they talk about it:https://mobile.donanimhaber.com/asagidaki-transistorun-kodunu-bilen-varmi-t01a--81829927

author: lmagalhaes
author_rank: Contributor
timestamp: January 03, 2022, 09:17:12 am
content: The MOSFET is from a nebulizer from TDK. I have seen replacements online but wanted to get one from a reputable source. Here's a photo of the board:

author: asis
author_rank: Frequent Contributor
timestamp: January 03, 2022, 02:37:40 pm
content: Hi,Are you sure all the components are installed on the PCB?You have no inductances L1, L2, L3 and the emitter of the transistor (rightmost pin) is not connected anywhere.You will show the PCB from below.At the same time, ring the transistor. This is probably n-p-n.

author: lmagalhaes
author_rank: Contributor
timestamp: January 03, 2022, 05:08:36 pm
content: The board is not complete. The inductors have been removed. This board is NOK and I was pulling some components to try and fix another one that is NOK. The center contact of the MOSFET is connected directly to V+ (Output of the full bridge rectifier), which is why I was getting confused... because, usually, you use a PMOS to switch V+. And the center pin is connected to the heatsink, which I assume to be the drain. But testing the mosfet with a multimeter I'm not figuring out which one is which. Either this isn't a switching configuration or I don't know.Here's a picture of the back:

author: BrokenYugo
author_rank: Super Contributor
timestamp: January 03, 2022, 07:09:26 pm
content: Some digging suggests this board is sold by TDK as a whole module, so it's probably a secret part number. You'll have to reverse engineer it to spec an appropriate part or buy some salvaged ones from China and hope at least one of the lot are good.https://product.tdk.com/en/search/sw_piezo/sw_piezo/nebulizer/info?part_no=NB-59S-09S-0

author: asis
author_rank: Frequent Contributor
timestamp: January 04, 2022, 09:23:09 am
content: Hi,You break spears in vain.The probable cause is the ultrasonic emitter itself.Titanate - barium emitters fail if there is no water, in fact - load.Therefore, there is no generation in your case.

author: fzabkar
author_rank: Super Contributor
timestamp: January 04, 2022, 06:54:08 pm
content: FWIW, this TDK patent contains a simple circuit based around an NPN transistor:https://www.google.com/patents/EP0546964A1TDK has many more patents on this subject. I got tired of reading them. :-)

author: lmagalhaes
author_rank: Contributor
timestamp: January 05, 2022, 10:11:07 am
content: But in those patents there's always a crystal or a timer to generate the 1.6MHz output response. I can't see either of those components on this board ... Maybe it's inside that package ?

author: lmagalhaes
author_rank: Contributor
timestamp: March 17, 2022, 11:05:29 am
content: Reviving this old post. So, I couldn't get the datasheet for this BJT, however I identified it, using a multimeter, as a NPN. After that, I searched for a package name and searched for other NPN BJTs on Mouser with the same package and ordered a couple. Analyzing the datasheets, they are rather different from each other and I had one working well, one somewhat working and the other two barely work (in terms of the nebulizer unit working). I've noticed that the one that works best has the highest transition frequency and the highest minimum hFE, however it is described in the datasheet as DC gain and this circuit is working at 1.6MHz.Instead of keeping purchasing other BJTs blindly, I'd like to simulate the circuit in LTSpice and "experiment" with different transistors. However, after copying the circuit to LTSpice, the output doesn't oscillate. Here's the circuit:And here's the simulation result:Can anyone point me in the right direction ?

author: RoGeorge
author_rank: Super Contributor
timestamp: March 17, 2022, 11:19:03 am
content: If you want LTspice help, then attach the .asc file of your schematic, so others can run debug your circuit without spending time to redraw it.Also try adding "startup" and/or "uic" after .tran 100ms (corresponding to the check boxes "Start external DC at 0V" and "Skip initial operating point" in the GUI for setting .tran parameters), might help starting the oscillations faster.

author: lmagalhaes
author_rank: Contributor
timestamp: March 17, 2022, 11:51:57 am
content: Here you go. Adding "uic" did, in fact, show some oscillations. However, it seems like it's rectified ... only the positive part of the wave is showing.

author: jasburg
author_rank: Newbie
timestamp: November 21, 2023, 02:40:00 pm
content: Hi there,Long shot since this post has not been active in ages.The BJT of my nebulizer board is also not working so I was wondering if you managed to identify a suitable alternative for it in the end?Cheers

author: Jwillis
author_rank: Super Contributor
timestamp: November 22, 2023, 06:01:47 am
content: Quote from: jasburg on November 21, 2023, 02:40:00 pmSanken Electric T01A Unable to find data sheet. Probably obsolete . Seems to be some new old stock available from different sources.

author: eurgenca
author_rank: Regular Contributor
timestamp: November 22, 2023, 06:29:34 am
content: https://si.farnell.com/epcos/nb-59s-09s-0/ultrasonic-nebulizer-1-6-1-72mhz/dp/3490715

author: Vovk_Z
author_rank: Super Contributor
timestamp: November 22, 2023, 10:12:42 am
content: Isn't it a some kind of a thyristor?

author: jasburg
author_rank: Newbie
timestamp: November 22, 2023, 11:01:52 am
content: I am not entirely sure what exactly it is since there is no data available anywhere..I now ordered a replacement from aliexpress according to which it is TO-3P Power Transistor hoping that it has the same specs:https://www.aliexpress.com/item/4000874311455.html?spm=a2g0o.order_list.order_list_main.5.21ef1802KxQR0fI'll send an update once I have tested the board with the new component

author: Jwillis
author_rank: Super Contributor
timestamp: November 23, 2023, 08:12:42 am
content: Quote from: Vovk_Z on November 22, 2023, 10:12:42 amQuote from: jasburg on November 22, 2023, 11:01:52 amBased on a circuit diagram that closely resembles the TDK nebulizer board, I would reckon that it's a NPN BJT. The circuit show here shows a BUX40A. But that's in a TO3 package and not a TO3P.I'm curious to know what it is really.

author: altair
author_rank: Newbie
timestamp: December 25, 2024, 07:34:12 pm
content: Changed the simulation file a little.