3 ms·

There are bajillions of mosfets; you can certainly find another one that works even if it's a tiny bit more expensive.

by kayson 4y ago

dragontamer 4y ago
Sure. So name one, that's cheap, readily available from many manufacturers, through hole, with 100mA+ or so Ids, low enough capacitance to be used with a microcontroller like ESP32. Most of the good MOSFETs I'm aware of are SMT only, which is not beginner friendly. 2N7000 through hole is extremely available damn near everywhere. All companies have a clone of the venerated, classic MOSFET. EDIT: Its also been used in various beginner circuits for 40 years, so you can pickup an old book from the library and see those 2N7000 around and use those designs today. ---------- Honestly, if you're doing through-hole on ESP32, I suggest using a resistor + 2N2222 BJT instead of the MOSFET. But I think 2N7000 is easier (fewer parts, in particular no resistor needed). But that's a 5V design. The 2N2222 also requires you to leak a decent amount of current through the Vbe / Ibe (while 2N7000 is like 1uA or less leak Vgs / Igs). But... 5V and 2N7000 Jellybean + throughole is really easy to use. Its definitely a big advantage to Arduino IMO, and I'm glad that they're keeping the 5V driving capability in this newest version.
- taylorportman 4y ago
  There is an IRL series. I just got some IRL540N's https://learnarduinonow.com/2017/06/02/logic-level-mosfets-irl-or-irf.html https://learnarduinonow.com/2017/06/02/logic-level-mosfets-i... But I got arduinos to go with them because I doubt they will work directly from an esp. I think the big reason arduino can get away with charging so much is they must have some sort of educational institution market buying their products. The software and community support that comes with them is nice to have.
  - deleted 4y ago
    [deleted]
- exmadscientist 4y ago
  The 2N7000 has the minor, trifling, potentially catastrophic flaw that many (most?) of them have completely unprotected gates. (In fact, it's one of the few parts you can reliably source that still offers this feature if you should need it, say for FET party tricks.) This means that the bloody things blow up if you so much as look at them funny. You absolutely need proper ESD precautions to use these things reliably. Many a student has come to the false conclusion that they didn't understand how to use MOSFETs when, in fact, they had just inadvertently blown up some or all of their crappy old 2N7000s. This is not really what you want for a "jellybean" part. Yes, you can be careful about this and order the right part number to get a newer protected-gate version, but at that point please do us all a favor and specify some non-stone-age part.
  - dragontamer 4y ago
    > In fact, it's one of the few parts you can reliably source that still offers this feature if you should need it, say for FET party tricks. Few? Tons of MOSFETs have no ESD protection, because that ESD protection diode has uA levels of leakage current in practice. Both MOSFETs discussed in this subthread (IRL540 and AO3401A) are both unprotected MOSFETs that blowup from ESD. In fact, no one has even listed an ESD-protected MOSFET yet. > Yes, you can be careful about this and order the right part number to get a newer protected-gate version Unprotected MOSFETs have nothing to do with "old" or "new". Its because that protection diode has a number of characteristics (in particular: sucking currents in a different direction than expected and changing the circuit) that needs to be carefully considered. You can't just replace unprotected MOSFETs with protected ones and hope that your circuits work. You very well could be shorting out some circuit inadvertently.
    - exmadscientist 4y ago
      Gate protection zeners are much more common in the more modern, higher-performance parts. So if you are used to using dinosaurs, you might think they're rare. Also, manufacturers occasionally get sloppy about noting their existence; you really need to see an I_GSS spec to be sure. (And because, well, if you're concerned about gate leakage, that is the spec!) The 2N7000 is significantly worse than other MOSFETs. I don't know if that's because it's older, because its fab process is worse or was worse at one time, because it's easy to get those TO-92 legs into trouble, or just because of the die's low C_iss, but it's one fragile little bastard. The 2N7002 seems to be much better! > Unprotected MOSFETs have nothing to do with "old" or "new". Yes, they do, because the 2N7000 is older (1986) than integrated gate protection devices! Anything you see with them isn't a "true" 2N7000, even if it might meet the JEDEC spec sheet (which is rather hard to turn up...). Modern versions might have protection or might not (check the letters at the end of the part number... and hope you've got the right era of datasheet... and hope you've got the original MPN and don't have to read the condensed markings on the parts themselves... oh and hope you know the actual manufacturer!), but if they're older then they certainly won't have protection. So it kind of is an old (nope) versus new (maybe) thing. > You can't just replace unprotected MOSFETs with protected ones and hope that your circuits work. You very well could be shorting out some circuit inadvertently. Okay, technically, yes. In practice, no. Enhancement MOSFETs are usually used for power/switching applications, which won't care one damn bit about a silly diode, or in feedback loops for analog applications, which again won't care much. For various reasons, JFETs and depletion MOSFETs are usually preferred in analog-land, along of course with ICs. That's not to say you don't see discrete enhancement MOSFETs, but it's very, very uncommon. (And when I try to design that sort of stuff, I always seem to get stuck on not being able to find a FET without the pesky diodes built in. Sigh.)
cellularmitosis 4y ago
But could a hobbyist who is following one of the bazillion tutorials which calls for a 2N7000 or other non-logic-level mosfet? Does that hobbyist even know what a threshold voltage is? These are barriers to entry which are removed by 5V IO. While I love digikey’s parametric search, I’ve gotten feedback from more than one budding hack after that it is “too complicated and confusing”

There are bajillions of mosfets; you can certainly find another one that works even if it's a tiny bit more expensive.

by kayson 4y ago

There are bajillions of mosfets; you can certainly find another one that works even if it's a tiny bit more expensive.

Sure. So name one, that's cheap, readily available from many manufacturers, through hole, with 100mA+ or so Ids, low enough capacitance to be used with a microcontroller like ESP32. Most of the good MOSFETs I'm aware of are SMT only, which is not beginner friendly. 2N7000 through hole is extremely available damn near everywhere. All companies have a clone of the venerated, classic MOSFET. EDIT: Its also been used in various beginner circuits for 40 years, so you can pickup an old book from the library and see those 2N7000 around and use those designs today. ---------- Honestly, if you're doing through-hole on ESP32, I suggest using a resistor + 2N2222 BJT instead of the MOSFET. But I think 2N7000 is easier (fewer parts, in particular no resistor needed). But that's a 5V design. The 2N2222 also requires you to leak a decent amount of current through the Vbe / Ibe (while 2N7000 is like 1uA or less leak Vgs / Igs). But... 5V and 2N7000 Jellybean + throughole is really easy to use. Its definitely a big advantage to Arduino IMO, and I'm glad that they're keeping the 5V driving capability in this newest version.

taylorportman 4y ago
There is an IRL series. I just got some IRL540N's https://learnarduinonow.com/2017/06/02/logic-level-mosfets-irl-or-irf.html https://learnarduinonow.com/2017/06/02/logic-level-mosfets-i... But I got arduinos to go with them because I doubt they will work directly from an esp. I think the big reason arduino can get away with charging so much is they must have some sort of educational institution market buying their products. The software and community support that comes with them is nice to have.
- deleted 4y ago
  [deleted]
exmadscientist 4y ago
The 2N7000 has the minor, trifling, potentially catastrophic flaw that many (most?) of them have completely unprotected gates. (In fact, it's one of the few parts you can reliably source that still offers this feature if you should need it, say for FET party tricks.) This means that the bloody things blow up if you so much as look at them funny. You absolutely need proper ESD precautions to use these things reliably. Many a student has come to the false conclusion that they didn't understand how to use MOSFETs when, in fact, they had just inadvertently blown up some or all of their crappy old 2N7000s. This is not really what you want for a "jellybean" part. Yes, you can be careful about this and order the right part number to get a newer protected-gate version, but at that point please do us all a favor and specify some non-stone-age part.
- dragontamer 4y ago
  > In fact, it's one of the few parts you can reliably source that still offers this feature if you should need it, say for FET party tricks. Few? Tons of MOSFETs have no ESD protection, because that ESD protection diode has uA levels of leakage current in practice. Both MOSFETs discussed in this subthread (IRL540 and AO3401A) are both unprotected MOSFETs that blowup from ESD. In fact, no one has even listed an ESD-protected MOSFET yet. > Yes, you can be careful about this and order the right part number to get a newer protected-gate version Unprotected MOSFETs have nothing to do with "old" or "new". Its because that protection diode has a number of characteristics (in particular: sucking currents in a different direction than expected and changing the circuit) that needs to be carefully considered. You can't just replace unprotected MOSFETs with protected ones and hope that your circuits work. You very well could be shorting out some circuit inadvertently.
  - exmadscientist 4y ago
    Gate protection zeners are much more common in the more modern, higher-performance parts. So if you are used to using dinosaurs, you might think they're rare. Also, manufacturers occasionally get sloppy about noting their existence; you really need to see an I_GSS spec to be sure. (And because, well, if you're concerned about gate leakage, that is the spec!) The 2N7000 is significantly worse than other MOSFETs. I don't know if that's because it's older, because its fab process is worse or was worse at one time, because it's easy to get those TO-92 legs into trouble, or just because of the die's low C_iss, but it's one fragile little bastard. The 2N7002 seems to be much better! > Unprotected MOSFETs have nothing to do with "old" or "new". Yes, they do, because the 2N7000 is older (1986) than integrated gate protection devices! Anything you see with them isn't a "true" 2N7000, even if it might meet the JEDEC spec sheet (which is rather hard to turn up...). Modern versions might have protection or might not (check the letters at the end of the part number... and hope you've got the right era of datasheet... and hope you've got the original MPN and don't have to read the condensed markings on the parts themselves... oh and hope you know the actual manufacturer!), but if they're older then they certainly won't have protection. So it kind of is an old (nope) versus new (maybe) thing. > You can't just replace unprotected MOSFETs with protected ones and hope that your circuits work. You very well could be shorting out some circuit inadvertently. Okay, technically, yes. In practice, no. Enhancement MOSFETs are usually used for power/switching applications, which won't care one damn bit about a silly diode, or in feedback loops for analog applications, which again won't care much. For various reasons, JFETs and depletion MOSFETs are usually preferred in analog-land, along of course with ICs. That's not to say you don't see discrete enhancement MOSFETs, but it's very, very uncommon. (And when I try to design that sort of stuff, I always seem to get stuck on not being able to find a FET without the pesky diodes built in. Sigh.)

cellularmitosis 4y ago

But could a hobbyist who is following one of the bazillion tutorials which calls for a 2N7000 or other non-logic-level mosfet? Does that hobbyist even know what a threshold voltage is? These are barriers to entry which are removed by 5V IO. While I love digikey’s parametric search, I’ve gotten feedback from more than one budding hack after that it is “too complicated and confusing”