Transistor Identification?

Bordodynov

Joined May 20, 2015
2,995
11A MMBD1501A National Semiconductor SOT23 Si diode 200V 100mA

I advise testing the element using a multimeter (directly on the board).
 

Thread Starter

Andrew Barry

Joined Jun 5, 2018
8
hi Andrew,
Welcome to AAC.
Are you saying the transistor faulty.?
If yes, what tests have you done.
E
Hi

Thank you for the welcome

This a photo of the same component that broke off on another exact PCB.I did locate the transistor on the floor (luckily) and it had the same markings however I have since misplaced it. I have an LCR Pro1 tweezers coming very shortly. What would you like me to check as I am new to testing transistors.

-Andrew
 

Thread Starter

Andrew Barry

Joined Jun 5, 2018
8
For a drone. Buying a replacement board is $100. An electrical repairer will slap it back for me for free only if I find the correct part.
 

Thread Starter

Andrew Barry

Joined Jun 5, 2018
8
The IRLML6401 is only my guess as shown in the last photo. Could even be something different but that is my guess. Not sure if Q2 is 11A 1A or !1A.
 

DECELL

Joined Apr 23, 2018
96
I don't think will be offering bother helping rude people again. Clearly my time is yours to use and waste as you wish.
 

ebp

Joined Feb 8, 2018
2,332
Fairchild marks the MMBT3904 1A. The 2N3904 and its surface mount versions are probably very close to the most common transistor on the planet. DigiKey has half a million MMBT3904s on the shelf.
I'm reasonably certain the first character is not 1. Every detail marked usually has specific meaning, such as date code, country or production facility of origin, etc.
 
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ebp

Joined Feb 8, 2018
2,332
The fact that Q2 in the schematic has a 10k resistor in series with the (gate or base) says it is very unlikely that it is a MOSFET. The only reason to use such a resistor with a FET is if there is some desire to slow the switching or the FET has a built-in zener to protect the gate and the drive voltage exceeds the zener voltage, so current limiting is required. 10k makes perfect sense for a base resistor for a bipolar driven with a 5V signal and with collector current of a couple of milliamps.

[EDIT] Assuming Q1 is a P-channel MOSFET turned on by Q2 and 5 volts is the control signal for Q2, just about any NPN bipolar or logic-level N-channel MOSFET with the pins in the right places and a voltage rating of about 6 or more will work.
 
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Thread Starter

Andrew Barry

Joined Jun 5, 2018
8
Fairchild marks the MMBT3904 1A. The 2N3904 and its surface mount versions are probably very close to the most common transistor on the planet. DigiKey has half a million MMBT3904s on the shelf.
I'm reasonably certain the first character is not 1. Every detail marked usually has specific meaning, such as date code, country or production facility of origin, etc.
Fairchild marks the MMBT3904 1A. The 2N3904 and its surface mount versions are probably very close to the most common transistor on the planet. DigiKey has half a million MMBT3904s on the shelf.
I'm reasonably certain the first character is not 1. Every detail marked usually has specific meaning, such as date code, country or production facility of origin, etc.
Turns it is indeed a Fairchild MMBT3904. The "!" in front of the 1A turns out to be the factory of manufacture and the dot indicates PIN 1. Google "Fairchild sot23 markings" and click on images. You will see other components also marked with the "!" in front of the code marking. Thank you to everyone who helped out on this marking. I have now learnt something new and hope someone else does too.
 
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