SMD code 8I in SOT-23
Marking codes are not standardised, and the same code is reused by unrelated makers for unrelated parts. Below is every part in our tables printed with it, and any printed with a code that is easy to misread as it, from the manufacturers' own marking tables and published code lists.
3 parts in SOT-23 are printed 8I
Not sure which one you have?
Answer up to 4 quick questions and these 5 parts are ranked, with a meter test that settles it. It works on a dead part too.
DTC123TN3SOT-23Digital transistor (NPN, resistors built in), CYStekDigital transistor (NPN, resistors built in)CYStek
- What it is
- Digital transistor (NPN, resistors built in)
- Maker
- CYStek
- Package
- SOT-23
- Pins
- 3
- Details
- NPN digital (resistor-equipped) transistor, R1 2.2K, R2 None
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Digital transistor.
UN2218SOT-23PanNot recordedPan
- What it is
- Not recorded
- Maker
- Pan
- Package
- SOT-23
- Pins
- 3
- Details
- Si-npn-Digi: Sw, 50V, 100mA, 200mW, 150MHz, R1/R2=510R/5k1
- Source
- Published code list
Is it dead? The meter test is below: This part.
UNR2218SOT-23PanNot recordedPan
- What it is
- Not recorded
- Maker
- Pan
- Package
- SOT-23
- Pins
- 3
- Details
- Si-npn-Digi: Sw, 50V, 100mA, 200mW, 150MHz, R1/R2=510R/5k1
- Source
- Published code list
Is it dead? The meter test is below: This part.
2 more parts have no package on record. Nothing rules them out, so they stay.
UN9218JPanNot recordedPan
- What it is
- Not recorded
- Maker
- Pan
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Si-npn-Digi: Sw, 50V, 100mA, 125mW, 150MHz, R1/R2=510R/5k1
- Source
- Published code list
Is it dead? The meter test is below: This part.
UNR9218JPanNot recordedPan
- What it is
- Not recorded
- Maker
- Pan
- Package
- Not recorded
- Pins
- Not recorded
- Details
- Si-npn-Digi: Sw, 50V, 100mA, 125mW, 150MHz, R1/R2=510R/5k1
- Source
- Published code list
Is it dead? The meter test is below: This part.
Is it dead? One meter test per kind
Parts of the same kind are tested the same way, so each test is here once. Each part above points to its own.
Digital transistor
Ohms range, part lifted. The datasheet gives the built-in resistors: R1 in series with the base, R2 from base to emitter.
Working, it reads
Base to emitter reads about R1 plus R2 either way round, about 20 kΩ on a 10 k and 10 k part, give or take their wide tolerance. Collector to emitter reads open. A part with no R2 reads a junction behind R1 one way instead.
Dead, it reads
- Collector to emitter the same both ways, near 0 Ω with a continuous beep: shorted.
- From the base, open or far above R1 plus R2: R1 has failed. Static damage shows here most often.
- Base to emitter near 0 Ω: failed short.
- On the board
- this is a first look only: the meter reads every path between those pins, and a short can be a neighbour. Lift one leg before you condemn it.
- Compare:
- The readings depend on the resistor values, so an identical part elsewhere on the board is the surest reference. Measure it the same way.
- Watch for:
- On the diode range a good part with 10 kΩ resistors reads open on every pair, so a good part looks dead there. Use the ohms range.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
This part
Diode range and ohms range, part lifted.
Working, it reads
Depends on what it is. The datasheet, or an identical part, says.
Dead, it reads
- Between two pins, the same reading both ways, near 0 V with a continuous beep: shorted.
- Open between every pair of pins: failed open, or a part that reads open when working.
- On the board
- this is a first look only: the meter reads every path between those pins, and a short can be a neighbour. Lift one leg before you condemn it.
- Compare:
- If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
Printed with a code easy to misread as 8I
One character differs, and it is one that is easy to confuse under a lamp. Each code has a page of its own.
Codes not listed here are printed on 3 more parts.
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