Veraxis
Active Member
Hello all,
A bit of background: I was recently watching a video online describing a circuit which used discrete transistors. The individual making the video was an engineer from Scotland, so all of his circuits were based around the BC-family of transistors commonly used in the UK, which I tend to be less familiar with. This got me thinking about all of the various transistors that are used as "go-to" transistors by hobbyists.
There are plenty of lists online of "common transistors" that recommend what type of transistors to keep on hand, but very few try to give details as to why they are used or how people choose to apply them. This can be especially confusing when different parts of the world have different conventions for which transistor types they use, so I thought I would try to compile my own list of "common transistors" and then try to give some of the reasoning and ways in which they are used so that new hobbyists or hobbyists from other countries could get a better sense of the applications for a particular transistor.
For each transistor, I give a brief summary of how I have typically seen them used. For NPN BJTs or N-channel FETs, I also list its matching PNP or P-channel complement if it has one (in parentheses). Naturally, there are going to be MANY exceptions for all of these, but I think it can be useful to just give the broad strokes on how hobbyists generally use them. There is probably a lot of overlap between regions where a particular value is used in many places, so for the moment I have only broken the small signal BJTs into seperate regions.
tl;dr: I am looking for community input here, so feel free to suggest changes, corrections, or submit your own transistors to the list with descriptions. That said, I am mainly looking to just cover the major hobbyist "staples" rather than list every single transistor, so try to keep it to transistors that you have seen used by multiple people across many designs. I'm looking to avoid just listing tech specs and instead give general descriptions and typical applications.
I dunno, does this seem like a useful direction to pursue that could be used as a reference for people? I would be curious to see what people have to say about the various families and why certain values are preferred over others.
[Purple text in brackets will be used to mark comments and areas that I would like to improve.]
Small signal BJT (TO-92):
US/Canada:
UK/Europe [may need to be broken into two or more regions?]:
[I see the Japanese "2S" family used on many designs, but I'm not sure if they are particular to any countries/regions or what values are considered the most common to use.]
Small signal FET (TO-92):
Power BJT:
IRF2805: N channel mosfet, switching applications, microcontroller applications
IRF1405: N channel mosfet, switching applications, microcontroller applications
IRF5305: P channel mosfet, switching applications, microcontroller applications
RFP30N06LE, FQP30N06L (complement FQP27P06?): N channel mosfet, switching applications, microcontroller applications
Edit credits:
MikeMI (correction about TIP100-family usage)
DerStrom8 (clarification on P-type complements)
kinarfi (addition of IRF3205, IRF4905, and IRF2805)
Cheers,
JLNY
A bit of background: I was recently watching a video online describing a circuit which used discrete transistors. The individual making the video was an engineer from Scotland, so all of his circuits were based around the BC-family of transistors commonly used in the UK, which I tend to be less familiar with. This got me thinking about all of the various transistors that are used as "go-to" transistors by hobbyists.
There are plenty of lists online of "common transistors" that recommend what type of transistors to keep on hand, but very few try to give details as to why they are used or how people choose to apply them. This can be especially confusing when different parts of the world have different conventions for which transistor types they use, so I thought I would try to compile my own list of "common transistors" and then try to give some of the reasoning and ways in which they are used so that new hobbyists or hobbyists from other countries could get a better sense of the applications for a particular transistor.
For each transistor, I give a brief summary of how I have typically seen them used. For NPN BJTs or N-channel FETs, I also list its matching PNP or P-channel complement if it has one (in parentheses). Naturally, there are going to be MANY exceptions for all of these, but I think it can be useful to just give the broad strokes on how hobbyists generally use them. There is probably a lot of overlap between regions where a particular value is used in many places, so for the moment I have only broken the small signal BJTs into seperate regions.
tl;dr: I am looking for community input here, so feel free to suggest changes, corrections, or submit your own transistors to the list with descriptions. That said, I am mainly looking to just cover the major hobbyist "staples" rather than list every single transistor, so try to keep it to transistors that you have seen used by multiple people across many designs. I'm looking to avoid just listing tech specs and instead give general descriptions and typical applications.
I dunno, does this seem like a useful direction to pursue that could be used as a reference for people? I would be curious to see what people have to say about the various families and why certain values are preferred over others.
[Purple text in brackets will be used to mark comments and areas that I would like to improve.]
Small signal BJT (TO-92):
US/Canada:
- 2N3904 (complement: 2N3906): often used for its high gain as an amplifier in low-current applications. Its small signal gain is highest in the 10mA region. Its high frequency range also allows it to be used in some RF applications.
- 2N4401 (complement: 2N4403): Has better gain at high current than 2N3904. It is generally used for medium current and switching applications in the 100mA range.
- 2N2222, PN2222 (complement: 2N2907): Considered to be a good compromise between 2N3904 and 2N4401. It is often used as a kind of generic transistor in applications where “any old transistor” will usually work. Also has a higher voltage “A” variant (e.g. 2N2222A).
UK/Europe [may need to be broken into two or more regions?]:
- BC546, BC547, BC548 (complement: BC556, BC557, BC558): [need descriptions from someone familiar with these families]
- BC337, BC338 (complement: BC327, BC328):
- BC182, 183, 184 (BC212, BC213, BC214):
[I see the Japanese "2S" family used on many designs, but I'm not sure if they are particular to any countries/regions or what values are considered the most common to use.]
Small signal FET (TO-92):
- 2N7000: used as a general purpose enhancement mode MOSFET. Has a relatively high transconductance for a small signal FET.
- MPF102: although discontinued, this high frequency JFET has been a staple in amateur radio for RF oscillator circuits. With no direct replacement, this part is still sometimes used in newer designs. [there may be inaccurate info here. If HAMs have started adopting a replacement, let me know what it is so I can list it]
Power BJT:
- 2N3055 (complement: MJ2955): a TO-3 package power BJT often used as a class AB pair in audio power amplifiers.
- TIP31, TIP41 (complement: TIP32, TIP42): a TO-220 package power BJT used in switching applications. Has moderate gain at high current. Also has higher voltage “A,” “B,” and “C,” variants (e.g. TIP31C).
- TIP100/1/2 (e.g. TIP102), TIP120/1/2 (complement: TIP105/6/7, TIP125/6/7): a TO-220 package Darlington pair power transistor often used for switching applications. Popular with microcontroller enthusiasts for being easily driven by logic-level signals with a resistor in series with the base.
- MJE340 (complement: MJE350): a medium-power TO-126 package BJT often used in audio amplifiers. often used as buffers to the final power transistors or as a “VBE multiplier” for biasing.
- IRF510, IRF540, IRF630, and others (complement: IRF9510, IRF9540, IRF9630, etc.) a large family of TO-220 MOSFETs often used in switching applications or in class AB power amplifiers. Higher current “N” variants (e.g. IRF9540N) also exist. [What would be the best approach to the topic of large families like this where many similar parts from the same family are used?]
- IRF3205 (complement: IRF4905): a TO-220 MOSFET with low on resistance and high current handling capabilities. often used in switching applications and popular with microcontroller enthusiasts as a high current driver.
IRF2805: N channel mosfet, switching applications, microcontroller applications
IRF1405: N channel mosfet, switching applications, microcontroller applications
IRF5305: P channel mosfet, switching applications, microcontroller applications
RFP30N06LE, FQP30N06L (complement FQP27P06?): N channel mosfet, switching applications, microcontroller applications
Edit credits:
MikeMI (correction about TIP100-family usage)
DerStrom8 (clarification on P-type complements)
kinarfi (addition of IRF3205, IRF4905, and IRF2805)
Cheers,
JLNY
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