Detection of a sot-23 Transistor marked y1

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Hello guys

 

On a board i have a component that on the top overlay its marked Q1 so its likely a transistor. The package is SOT-23 and top of it its written y1.

When testing it by diode tester, a pin behave like the Base pin but the voltage across that pin and two other pins are equal.

So i can not find out which pin is Emitter or Collector. I made a circuit for test it directly the result was that it conduct two way from pin1 to pin2 and vice versa when the base is connected to the vcc through a resistor.

 

 

regards.

Last Edited: Mon. Jul 31, 2017 - 12:23 PM
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A quick Google suggests it might be a zener diode.

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Could be a bipolar resistor or (MOS) fet also.

Some time ago I got an older kit of a transistor tester for my birthday and they work amazingly well for such an affordable piece of equipment.

(My older version has a 16x2 character LCD)

 

https://www.aliexpress.com/whole...

 

These little testers can (often) tell you what is connected to it's leads.

N / P channel (mos) fets

N / P bipolar tansistors, darlingtons ( Measure Hfe also)

diode (single dual)

triac, thyristors,

resistors.

capacitors (Also measure  ESR).

 

hidian wrote:
result was that it conduct two way from pin1 to pin2 and vice versa when

Looks like a MOSfet then.

All MOSfets have an inherent paracitic diode between the drain and source. That is probably the diode you have measured.

https://en.wikipedia.org/wiki/MO...

Paul van der Hoeven.
Bunch of old projects with AVR's:
http://www.hoevendesign.com

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Sot-23, looking at the side with two pins, base is on the left, emitter is on the right and collector is the single pin on top.

 

When I google "SMD CODE Y1", most of the sot-23 devices are zener diode, with one npn transistor. 

Try tracing the rest of the circuit to determine of it is a diode or transistor. 

 

Post a good pic of the board if you need help.

 

Jim