Jellybean hobbyist general purpose transistors.. - Page 1
Forum section: electronics / beginners

author: Vtile
author_rank: Super Contributor
timestamp: October 12, 2017, 11:28:44 pm
content: I have started to think that I stock a few hundredgeneral purpose through hole transistors (an investment of a few tens of bucks). To be sure I will have them to tinker around as to me it seems that the jellybean variety is vanishing or vanished already from THTs.I'm mostly thinking of small signal, low freq (<200MHz), throw in buffer etc. general purpose uses of tinkering and maybe slobby repair or hack here and there.BJTs:BC547B(npn) & BC557B(pnp) comes to my mind.Is there other worth to look that are still readily available.Darlington models to maybe look at?.JFETIs there cheapish (<$0.50 ) replacement for 2n4117 other than mbf4117(smd). It seems to be pretty alone in fart detector range.MOSFETFor logic level switching use. Any ideas, in leds/signals on/off range of power. Should be also as robust as possible for ESD and ideally should have the protective diodes. 2N7000 ?? or were it JFET&BJT hybrid, hmm.Known matched pairs (for that random differential stage) that wouldn't cost arms and legs and could still be found as THTs. ..none or should I look from IC listings..Any other than TO-92 cases to look at for jellybean THT parts. Metal cans seems to be premium only now.

author: rstofer
author_rank: Super Contributor
timestamp: October 13, 2017, 12:09:29 am
content: 2N2222A2N3904,5,6

author: Cerebus
author_rank: Super Contributor
timestamp: October 13, 2017, 12:31:30 am
content: BJTs: There's always the old 2N3904 and 2N3906, widely available, cheap as chips, both quite quiet (NPN 1.8 nV/sqrt(Hz)), easy to get through hole and SMD versions, 300 MHz Ft.JFETs: In the low leakage JFET arena, nope nothing cheap. As you say, MMBF4117 is widely available at low cost but that's about it. PN4117 can be had in TO-92 but expect to pay around £1.50-£2 GBP each in small quantities. 2N4117A is also still available at similar prices. Both from Linear Systems.And if Sir needs to ask the price of dual monolithic JFETs then Sir might find them to be *ahem* beyond his budget. I'm seriously considering a bulk purchase of some dual JFETs and laying them down, like a fine port, for the next generation.J113 in most packages and PN/MMBF4393 in most packages are easy to find and inexpensive. Both good switches and fair amplifiers up to VHF at least.MOSFETS: BS170 is my go to for a discrete, breadboardable N-Channel MOSFET in TO-92. BS250 for a roughly complementary P-Channel. If you can find a small signal discrete MOSFET with a separate substrate terminal (so you can dodge the body diode problem) in current production at sane prices, I want to know about it.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 13, 2017, 01:49:25 am
content: FWIW, low leakage parts aren't jellybean, it's kind of contradictory there.I go with:2N3904/6, 4401/3 for more current, and PBSS303NX/PX for even more. Change 2N/MMBT when SMT.Lower current, and faster: MMBTH10/81, BFR92A (though this exact one I think is obsolete now, so pick another similar part instead).Higher power: TIP31C/32C, 2SD1273 (hah, not jellybean at all, but I picked up a few before they went obsolete), MJE15020, FJPF13009 (high voltage)MOSFETs:2N7002, BSS84NDT3055LIRF510, 540, 640, etc.IRFZ46NSTP6N60M2etc.I rarely use JFETs, but I've picked '4393, '5486, J105, and such before. Others (who are actually experienced with low noise wideband design) are very fond of BF862 (which is now going obsolete, but there are newer equivalents from On Semi).Tim

author: JustSquareEnough
author_rank: Unknown
timestamp: October 13, 2017, 03:31:49 am
content: while may not always hold true i've found it helpful to learn what the "jelly bean" part # of a particular component is by going to mouser or digikey, go to the components category, sort by either lowest price OR stock on hand. doing this on the BJT will see 390x that were mentioned already at the top of the list.

author: jaromir
author_rank: Unknown
timestamp: October 13, 2017, 04:41:04 am
content: Quote from: Vtile on October 12, 2017, 11:28:44 pmI tend to use BC327/337, as those have higher Ic (800mA versus 100mA), being more useful for switching loads like relays or common anode/cathode of MUX-ed displays.

author: CJay
author_rank: Super Contributor
timestamp: October 13, 2017, 05:44:52 am
content: BC639/BC640BC54x/BC55xBD139/BD140TIP41/TIP42BS170, 2N7000 and I've a small stock of VN10KMAs T3sl4co1l says, I don't often use JFETs but have a small stock of them, I'll be looking for an alternative before they run out, BF862 and newer equivalents/versions look very promising.

author: David Hess
author_rank: Super Contributor
timestamp: October 13, 2017, 05:54:49 am
content: I would go with the 2N4401 and 2N4403 as the general replacements for almost all small signal general purpose bipolar transistors unless working above 30 volts a lot like with higher power audio amplifiers in which case the 150 volt 2N5401 and 2N5551 would be more suitable. But it is really difficult to go wrong with other choices like the PN2222A/PN2907A and BC327/BC337. Be warned that the BC series uses the CBE instead of more common ECB pinout. These are all higher current parts which can replace most lower current parts however this is also an advantage in switching applications where hfe will be more consistent.For matched pairs except in precision applications, I match them myself by measuring Vbe at the operating collector current (collector and base shorted) and thermally bonding the pair together.Darlington parts can always be built as needed.I agree with T3sl4co1l's commendation for the MPSH10/MPSH81 and MMBTH10/MMBTH81 as faster TO-92 and surface mount parts. Just do not expect RF transistors to perform well as fast saturated switches in switching applications.Get a small signal schottky diode like the 1N5711, BAT41, or BAT83 for use in baker clamps if you want to improve switching. The BAT41 with its 100mA current rating can do double duty in low current switching regulators.For 1 amp rectifiers, I tend to standardize on the fast recovery 1N4937 but there are lots of choices.The D44H11/D45H11 are 70W 80V 10A TO-220 bipolar power transistors suitable for regulation, audio, and switching applications with an Ft of 50 MHz. The MJE172/MJE182 are similar 12.5W 80V 3A transistors in the smaller TO-225 package.The situation with JFETs is annoying.There are too many MOSFET options for me to make a good recommendation. The problem with many of them is marginal switching on 3.3 or even 5 volts; the true logic level ones are more expensive.

author: CJay
author_rank: Super Contributor
timestamp: October 13, 2017, 06:03:59 am
content: Quote from: David Hess on October 13, 2017, 05:54:49 amThis is not always true.BC639/640 are ECB for instance.Cheap Chinese transistor tester is a very handy thing to have on the bench.

author: chris_leyson
author_rank: Super Contributor
timestamp: October 13, 2017, 06:42:23 am
content: I think at one time there were two different pin-outs for the BC184/214 so they are parts I would avoid.

author: Zero999
author_rank: Super Contributor
timestamp: October 13, 2017, 08:32:47 am
content: Quote from: jaromir on October 13, 2017, 04:41:04 amThe BC547 & BC557 have a higher current gain than the BC327 & BC227. I like to get the BC547Cand BC557Cbecause they have a high beta and aren't much more expensive than the B variants.

author: capt bullshot
author_rank: Super Contributor
timestamp: October 13, 2017, 09:01:34 am
content: As stated, there are too many MOSFETs.For small signal purposes up to driving LED matrices, IMO BS170 / BS250 are a good choice (I've done few hobby projects using them in the past)For some more current / voltage: IRF540, IRF840 (these are not logic level)For logic level: IRLZ44These are parts that I've used in the past, were easy to obtain and quite common back then.

author: Vtile
author_rank: Super Contributor
timestamp: October 13, 2017, 09:18:14 am
content: Thank you all for the information. I see what I can find with decent overall cost (product+shipment+handling+taxes).Good points that I also need to go through.For dual JFETs the only one I do know is the 2N5909 for (serious) instrumentation. I kick myself that I didn't get two (to just see what kind of animal it is) when they still were locally available way below ebay prices. Not that I would need one, but..The 4117 were my list just because it is what it is and it still is available in the discrete form. Unfortunately the A-subtype is not hobbyist friendly priced in any form, while MMBF4117 is. (unfortunately in SMD, but luckily SOT23 is still somewhat usable, without PCB and professional equipment.)It is true about handpicking and doing Darlingtons and pairs when needed (when you have the stock where to pick!!!). I just thought if there is known decent general types (BJT and/or JFETs).I'm personally accustomed to check the leg order as I traditionally have had that one piece of every transistor type pulled out from that random device (starting from ancient OC-series). So yeah a slight leg order variation doesn't put me (personally) down. I also have a bag full of old free soviet/VEF-riga parts including about ½kg of transistors my father did bring to me in late 90's when he traveled in the Baltic, but they are so wild and random.True also, if someone doesn't have the "$20 transistor tester", get one, I still wonder how I survived before.

author: Vtile
author_rank: Super Contributor
timestamp: October 13, 2017, 11:02:03 am
content: Quote from: Hero999 on October 13, 2017, 08:32:47 amBC547/557 is interesting as the A type have the least gain, while the C type the most. I settled in B-type in my own choice (as now), because the pricing, but let see what is the final decision.

author: jaromir
author_rank: Unknown
timestamp: October 13, 2017, 11:10:28 am
content: BC327/337 is also binned by manufacturer by gain - see herehttps://snag.gy/fzlU1o.jpgtaken fromhttp://www.mouser.com/ds/2/149/BC337-193546.pdf

author: Zero999
author_rank: Super Contributor
timestamp: October 13, 2017, 12:37:59 pm
content: If you want low cost, then the BC327 and BC547 with no prefix will be cheapest but the gain is pot luck.Use the BC327 & BC337 for switches. The Hfe is specified with VCE= 1V, which is low enough for most applications.Use the BC547 & BC557 for linear amplifiers. They have a higher bandwidth than the BC327 & BC337 and I believe are lower noise too.

author: David Hess
author_rank: Super Contributor
timestamp: October 13, 2017, 02:55:00 pm
content: Quote from: Hero999 on October 13, 2017, 08:32:47 amThe BC547/BC557 have higher current gain at lower collector currents, much lower collector currents. Where they are useful is low input bias and low collector current amplifiers where the input impedance is higher. The 2N equivalents are the 2N5087/2N5089 which are designed to operate at an even lower current. You can identify transistors like these by the test current used for their hfe and noise specifications:BC639/BC640 - 150mA Test Current2N4401/2N4403 - 150mA Test CurrentBC227/BC327 - 100mA Test Current2N3904/2N3906 - 10mA Test CurrentBC547/BC557 - 200uA Test Current (from noise figure)2N5087/2N5089 - 100uA Test CurrentIf I was doing low level audio work or building log/antilog amplifiers, then I would add the BC547/BC557 or 2N5087/2N5089 to my list of jelly bean parts.Quote from: Hero999 on October 13, 2017, 12:37:59 pmThe BC547/BC557 have lower current noise at low collector currents so may be used in higher impedance circuits. The BC327/BC337 would be more appropriate in low impedance circuits where voltage noise needs to be lower at the expense of current noise although they were intended as output drivers.

author: Vtile
author_rank: Super Contributor
timestamp: October 13, 2017, 05:19:46 pm
content: Thanks..Now I can navigate in this transistor jungle much easier.These coding methods started to hunt me, here is a simple explanation for Bxxxx types.http://www.audiobr.com.br/old/forum/kb.php_mode=article&k=267.htmlorhttp://www.radio-electronics.com/info/data/semicond/bipolar-transistor-bjt/numbering-codes.phpQuoteSo the European system actually have some information coded in, compared to JEDEC 2Nxxxx codes.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 13, 2017, 05:25:29 pm
content: Quote from: David Hess on October 13, 2017, 05:54:49 amOr the similar MPSA46, or whatever they are, from that family. MJE350 and complement are also quite popular for audio (driver stage), though the datasheet is sorely wanting. I think On Semi makes a detailed datasheet? Or, there are equivalent parts with good data out there, shop around.QuoteAlso, beware of oscillation, especially as you go over fT > 1GHz. Keep ferrite beads handy for use on the base or emitter pin.QuoteI'm partial to BAT85 and BAT54 (especially BAT54S, handy ESD clamp for logic I/O!), but they're all fine.And BAV99 for analog / low leakage ESD clamping.UF4004/7 for fast, higher voltage diodes, or SiC schottky for higher current and high speed, or Si schottky for low voltage and high speed. Protip: junction diodes are good for snubbers as they have lower capacitance. The forward recovery voltage (and thus peak voltage overshoot) isn't usually a problem in such application, but the capacitance is.QuoteFWIW, this is physics: MOSFETs rated 30V and up are physically different from those below. The Rds(on) tempco is large (usually 1.8-2.5 times higher at 150/175C than at 25C), and the gate threshold and turn-on-ness (i.e., transconductance) isn't very good. You can always adjust threshold (from negative Vgs(th) depletion mode, to enhancement with Vgs(th) up to 5V), but you can't adjust the slope of how fast it turns on. Point being, you can get "logic level" power FETs, with Vgs(th) around 0.8V, and they're usable at 5V drive, but they still turn on harder if drive is stepped up to 9V, say. They're also very slow at 5V, because drive current is limited by series resistance.Devices 20V and under, however, have a shallower Rds(on) curve, and much more transconductance. 12V devices are effective at 2.5V logic level and below. There's one part out there with Rds(on) in the microohms (for battery management)!So if you have an application that's on the borderline between choosing 20 and 30V devices, try to use 20V. To keep the circuit safe, put more effort into controlling peak voltages (add snubbers, use slower commutation, or a resonant design).Tim

author: orolo
author_rank: Frequent Contributor
timestamp: October 13, 2017, 08:23:32 pm
content: Quote from: Hero999 on October 13, 2017, 08:32:47 amI also stock the C series for the same reason, and the 'low noise, higher voltage' 550/560s since there is no great price difference.But there is a catch, that I first heard of from Bob Pease: the higher the beta, the lower the output impedance. It can be seen inthis datasheet: the 547A has 55.5k typical output impedance, the 547B 33.3k, and the 547C 16.6k, and it could go as low as 9k!. This can be very important when building current sources/sinks, active loads, etc. The beta-output impedance relationship seems to be (rougly) inversely proportional. This has led me to think seriously about stocking low beta versions of the transistor.TheVishay datasheet for the PNP partsquotes the same output impedances for the A,B,C series. IIRC, in the Art of Electronics, data suggested that PNP parts often have even lower output impedance (lower Early voltage).

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 13, 2017, 10:15:23 pm
content: Quote from: orolo on October 13, 2017, 08:23:32 pmOnly relevant to pure current mirrors without degeneration.Tim

author: bd139
author_rank: Super Contributor
timestamp: October 13, 2017, 10:58:37 pm
content: Jellybeans for me. I don't do SMD really. Well I do, but it's done with TH parts2n3904 (gp npn)2n3906 (gp pnp)2n2222 (plastic - switch/high Ic)bd139/bd140 (complimentary / med power npn - make nice compliance range current sources/sinks!)j113 (jfet)IRF510 (medium mosfet)bs170/2n7000 (same part! tiny mosfets).BD139 is my favourite if you didn't guess. They are literally the swiss army knife of transistors. Nice package, high Ft (150MHz+), Reasonable Ic, High Vce, quite difficult to blow up, cheap as chips.One thing to note, your average crappy 2 cent Fairchild 2N3904 has a better NF than any BC transistor, including the low noise 549 until you start getting into RF transistors. Keep the gain reasonable and there's a huge mileage in that part. Literally 90% of my designs use just the 2n3904/2n3906.Edit: also I've got a tube each of CA3096 and CA3028. CA3096 is a few well matched transistors in a DIL package. Great for current sources, compensated feedback for log amps. CA3028 is a can package with a diff amp in it which can be reconfigured in more ways that I care to imagine. Makes nice cascode amps etc. Shame they're both obsolete.

author: David Hess
author_rank: Super Contributor
timestamp: October 14, 2017, 02:26:59 am
content: Quote from: T3sl4co1l on October 13, 2017, 05:25:29 pmDid you mean the MPSA43/MPSA93? They are a little slower.The Motorola/On MJE371/MJE521 are the same way. They are recommended for specific applications but lack a full set of specifications. I ran across them when doing a search for fast TO-126, TO-225, and TO-220 parts to use in high performance regulators.The BD135 through BD140 are like that also. The ST and Fairchild datasheets say nothing about dynamic performance but there are SavantIC Semiconductor (who?) datasheets which say 190 MHz for the NPNs and 160 MHz for the PNPs. What?

author: CJay
author_rank: Super Contributor
timestamp: October 14, 2017, 07:33:46 am
content: Quote from: David Hess on October 14, 2017, 02:26:59 amThe BD139 makes an excellent little RF power transistor, 2-3W output across the HF bands and probably into low VHF (never tried it above 30MHz), it's not been a secret but it's also not that widely used, people seem to prefer the long obsolete 2SC Mitsubishi devices

author: bd139
author_rank: Super Contributor
timestamp: October 14, 2017, 08:50:44 am
content: Indeed. Most transistor selection appears to be religion.Recently I stopped someone paying £8 for an OC transistor in a circuit they didn’t understand just to copy it verbatim. A 2n3906 would do the job, arguably better as well!

author: orolo
author_rank: Frequent Contributor
timestamp: October 14, 2017, 09:59:33 am
content: Quote from: T3sl4co1l on October 13, 2017, 10:15:23 pmSorry for going a bit off topic, but honestly, I'm confused beacuse this beta thing has been bothering me for a time. Do you mean that there is a workaround for low rout, or that it's not relevant for current sinks and active loads? I've gone back to basics to see if I got this wrong, redoing example 2 here:http://leachlegacy.ece.gatech.edu/ece3050/notes/ISources/isources.pdf[There is an errata in the exercise: they changed m for n]. I attach the python code I used:Code:beta = 100.0 # Current gain.Va = 75.0 # Early voltage.Vbe = 0.65 # Base-emitter voltage.Vce = 8.00 # Collector-emitter voltage.rx = 40.0 # Base spreading resistance.Ic = 1.5e-3 # Collector current.Vcc = 15.0 # High rail.Vdd = -15.0 # Low rail.n = 2.0 # Emitter resistor Vbe multiplier.m = 10.0 # Stiff current multiplier at the base.Vt = 300.0*1.3806e-23/1.6022e-19 # Thermal voltage.alpha = beta/(1+beta)Re = (beta*n*Vbe)/((1+beta)*Ic)R1 = beta*(Vcc-Vdd-(n+1)*Vbe)/((m+1)*Ic)R2 = (beta*(n+1)*Vbe)/(m*Ic)r0 = (Va + Vce)/Icrep = (R1*R2/(R1+R2) + rx)/(1+beta) + alpha*Vt/Icrout = (r0 + rep*Re/(rep+Re))/(1.0 - (alpha*Re)/((rep+Re)))print "beta ", betaprint "va ", Vaprint "Vt ", Vtprint "Re ", Reprint "R1 ", R1print "R2 ", R2print "r0 ", r0print "rep ", repprint "Output resistance: ", routFor the same circuit, if beta=100, Va=75, the resistance of the sink is 379k, in agreement with the exercise. Now take beta=200, Va=75/2=37.5. The resistance drops to 215k. Even if beta=400, Va=37.5, the resistance is still 218k. Beta does not compensate for Va drop. If we go to the extreme, beta=600, Va=12.5, resistance drops to 100k. At least we can say that high beta parts underperform in this role. Isn't it just the same with a common emitter with active load: will a piece with 15k-9k output impedance give the same gain than a piece with 50k?Found Pease's article warning about high beta:http://www.electronicdesign.com/power/whats-all-vsubbesub-stuff-anyhow-part-2.Edit:Aha, I found it! What was spoiling the resistance of the current source was not the Va, but the choice of resistors R1 and R2. For high beta you need a much stiffer current at the base divider, m=100 or so. I think I'll need to think this over, much deeper.Thanks!

author: Vtile
author_rank: Super Contributor
timestamp: October 14, 2017, 10:38:43 am
content: How disturbing it is that VHF means very high frequenzy in a 30 MHz to 300 MHz range while every dog collar today transmit in Gigahertz range Wifi. Anyone else annoyed.

author: Vtile
author_rank: Super Contributor
timestamp: October 14, 2017, 11:38:29 am
content: Quote from: edavid on October 13, 2017, 10:54:48 pmIf the seller do refuge to sell outside the US. why you would suggest he would change his mind if someone in Europe would asks. Will no happen, especially since the products are in "high-tech" category, which have had traditionally paranoid export limits / licencing.In general ordering something from US ebay to Europe is far from hobby priced if the miracle happens and you find a seller who will ship to Europe.PS. I'm not angry to you, your intention is/was good and someone in US propably will benefit on that information.

author: bd139
author_rank: Super Contributor
timestamp: October 14, 2017, 12:07:52 pm
content: Indeed. China to Europe is cheaper than US to Europe!

author: David Hess
author_rank: Super Contributor
timestamp: October 14, 2017, 01:21:13 pm
content: Quote from: bd139 on October 14, 2017, 12:07:52 pmChina to the US is cheaper than the US to the US.But buying semiconductors and other electronic parts of questionable heritage does not strike me as being particularly economical.

author: bd139
author_rank: Super Contributor
timestamp: October 14, 2017, 01:29:58 pm
content: Depends on what you're buying really and what for. If it's for hobby purposes, it's difficult to justify a 10-15x price multiplier on some parts for an assured supply chain. If you're building industrial or commercial electronics, then there's no question however.

author: Vtile
author_rank: Super Contributor
timestamp: October 14, 2017, 04:50:08 pm
content: Quote from: Cerebus on October 13, 2017, 12:31:30 amObsolete, according to Farnell

author: Cerebus
author_rank: Super Contributor
timestamp: October 14, 2017, 05:08:29 pm
content: Quote from: Vtile on October 14, 2017, 04:50:08 pmThat's Farnell's odd way of sayingwearen't stocking this any more.Digikey have about 45,000 MMBF4393 on hand and about 1000 each of 2N4393 and PN4393. Looks like OnSemi are dropping the TO-92 packages soon, but there are lots of others out there who aren't e.g. PMBF4393 from NXP, marked active.Nevertrust Farnell or RS's indications of part lifetime status.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 14, 2017, 05:19:34 pm
content: Quote from: orolo on October 14, 2017, 09:59:33 amDegeneration was the key I mentioned. Negative current feedback improves the constant-current-y-ness of the output. It doesn't take much: a current mirror at 1mA (r_e ~= 26 ohms) benefits greatly from R_E = 100 ohms, while losing only 0.1V in saturation.QuoteHmm, I'll have to think about that.Does Vbe change much with respect to Vce? I know that it does -- it's an oft-overlooked mode of operation of the BJT, and can be used for detecting saturation -- but I don't have a feel for how much, and if it's exaggerated for high hFE or not. (I can imagine it might, as the base-thinning effect should act to increase r_bb' and Vbe. This would also be consistent with Vbe falling in saturation.)Tim

author: Vtile
author_rank: Super Contributor
timestamp: October 14, 2017, 07:12:42 pm
content: My go to list atm..BC549/559 C-type, low-noise version of 547/557. Vcb is substantially lower though. I think I get them in 2(npn):1 relation. For those frontend project failures.What about BC550/560 the noise figure seems to be specked even a bit lower, with same other specs.PN2222/PN2907 For true general use, rather low beta compared to BC459, 2n2222 is a such a classic, comparable to ua741 and 1n4148 and PN-series is fraction of the price.BD139/140 hmm...Small amount of bothJ113 as a general purpose JFETMMBF4117 as for a toying around partFor a igfet, BS170/2N7000, seems to work with 5V logic, while not fully on, but usable. I need to search on the mosfets a bit more.Anyone seen sot-23 to to-39 canning machine cheaply on chinese evilbays???

author: Zero999
author_rank: Super Contributor
timestamp: October 14, 2017, 07:30:23 pm
content: Quote from: Vtile on October 14, 2017, 10:38:43 amThe designations LF, MF, HF, VHF, UHF etc. came about when electronics were much slower, than they are today.

author: Vtile
author_rank: Super Contributor
timestamp: October 14, 2017, 07:40:24 pm
content: Quote from: Hero999 on October 14, 2017, 07:30:23 pmYep, when the silicon were still used for rectifier casings and not rectifying material.

author: David Hess
author_rank: Super Contributor
timestamp: October 14, 2017, 08:43:20 pm
content: Quote from: Vtile on October 14, 2017, 07:12:42 pmThat would be nice; there is a much larger variety now in small signal surface mount than leaded components. There are SOT-23 to leaded adapters but I have not seen any that I like.

author: floobydust
author_rank: Super Contributor
timestamp: October 15, 2017, 09:23:11 pm
content: Whatever happened to transistor technology improving?I found TIP30's in my junkbox date code 1973. hFE measured 5. Tossed them in the garbage.40+ years later, TIP30 still available and same specs. fT 3MHz, hFE 15-40, 30W.Planar, perforated emitter, epitaxial, mesa, alloy junction etc. I thought improvements occurred over the past few decades.I don't see why antique part numbers are still around.edit - added some silicon crystal configs

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 16, 2017, 12:23:27 am
content: TIP30 is another one of those ancient parts, tied to ancient specs. I don't know if TIPxx is JEDEC registered (they're originally Texas Instruments Plastic transistors), but they're widely available and genericized.You might get one that overperforms, or you might get one that's shite.I would be surprised to see a modern (since 80s) part perform as poorly as the originals, for the same reason I suggested regarding 2N3055 and such: the old diffusion lines are long since scrapped. Compatible parts are made on newer processes, but not benefiting from modern designs, so they still suck, like in hFE linearity and switching performance.You're more than welcome to buy new-designed parts, but, surprise surprise, they're more expensive.....Tim

author: bd139
author_rank: Super Contributor
timestamp: October 16, 2017, 07:00:54 am
content: 2n3055 is an interesting one. Modern ones are a lot better which means in some older kit the damn things oscillate violently. Have to stick a few pF across base/collector to make them shit again

author: Vtile
author_rank: Super Contributor
timestamp: October 16, 2017, 01:46:28 pm
content: But back in the day they used to handpick the 3-transistors used to every lunar lander and much details were given to select the right biasing currents for certain tolerance lot of transistors....But I can bet that at least half of the writers on this topic do have hands-on experience on this particular thing and not just "I have read about this historic procedure" like me.

author: David Hess
author_rank: Super Contributor
timestamp: October 16, 2017, 07:41:38 pm
content: The 2N3773 is another ones of those parts which morphed from 0.2 MH to 4.0 MHz.At one point Tektronix was using both the 0.3 and 0.8 MHz versions of the 2N3055 in the 76xx oscilloscopes and grading the 0.8 MHz parts for something (hfe or Ft?) to make 3 versions in the same product. The 2.0+ MHz 2N3055s came later and I gather that they are the junk bin of TO-3 power transistors where other parts which meet the 2N3055 specifications but not their own get tossed.I know of a couple times now where people had problems with oscillation in Tektronix high voltage inverters when replacing old and slow 2N3055s with fast modern ones. Using a 2N3771G or 2N3772G which are 0.2 MHz or a 2N3055AG or MJ15015 which are 0.8 MHz solved it. Tektronix changed something in their later inverters so they could use the 40 MHz D44H11 series (ring or perforated emitter transistor?) but I am not sure what, maybe the transformer?Quote from: Vtile on October 16, 2017, 01:46:28 pmIn designs which rely on matching, trivial grading can be the difference between excellent performance and adequate performance or working and not working. I try to avoid designs which rely on absolute specifications.

author: exe
author_rank: Unknown
timestamp: October 16, 2017, 09:34:19 pm
content: Quote from: floobydust on October 15, 2017, 09:23:11 pmThat's how it supposed to be. Manufactures should not change specs for the same part number. Besides that, I'm not sure BJTs are evolved much last ~20 years.Still, there are nice things like 2STA1942, MJE15028, BD139 (I like it because of low Vce(sat), there are smd equivalents). Use them, why using old junk?EDIT: fixed typo

author: bd139
author_rank: Super Contributor
timestamp: October 16, 2017, 09:58:12 pm
content: bd139 ftw

author: floobydust
author_rank: Super Contributor
timestamp: October 18, 2017, 02:19:53 am
content: I don't know the politics of jelly bean transistors. TIP31 is the cheapest TO-220 in town and not very sexy.I believe all these old parts got moved over to modern lithography, standard semi fab processes.Any improvements in the technology gave a "die shrink" to get costs down and fT up.I learned from IC's such as Signetics/Phillips/Raytheon NE5534 which I think was 28 masks.The TI NE5534 part behaves totally different, so I called them and asked WTF. They told me they purchased the rights and are using modern op-amp lithography/standard process that still "meets the specs" of the old part. So it's a different part with an old number and new fab process. Old parts don't have a lot of tests and datasheet specs so they are easy to rip off.The TI NE5532 I found terrible, literally kicked out of a recording studio for using it in repairs. Noisy and crappy sounding, compared to the old Signetics version.

author: exe
author_rank: Unknown
timestamp: October 18, 2017, 10:20:53 pm
content: Quote from: floobydust on October 18, 2017, 02:19:53 amYeah, this what I don't understand at all. There are many parts with the same part number, but from different manufacturers. And they are different! Esp. opamps. How can I make purchase decisions? For example, I measured bandwidth of NE5532 from TI and from ONSemi and there is a noticeable difference. Same for MC33079. Or transistors, I found 2STA1942 from ST to be better in my use-case than corresponding part from Toshiba (although, I tested only one of each).What's worse, nobody tests this. And even worse, manufacturers keep adjusting their processes... And on top of this a lot of rumors (esp. about audio stuff where audiophiles "reason" about sound quality with no understanding of how opamps work and no measurements).

author: Vtile
author_rank: Super Contributor
timestamp: October 18, 2017, 10:41:16 pm
content: Most of the shared parts what I see, are from the low end and/or old designs. OPAs in general aren't "amps" in sense of audio amp, but arithmetic calculators. If I set up the LM358 as a PID-controllerI doubt(since I haven't tested) that I would see really any difference between the manufacturers.

author: bd139
author_rank: Super Contributor
timestamp: October 18, 2017, 11:13:11 pm
content: This is why people buy stuff from Linear.Datasheets not datashits and proper specifications that are reliable.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 19, 2017, 04:58:41 am
content: Quote from: exe on October 18, 2017, 10:20:53 pmIf it meets the datasheet, and your application works based on datasheet information, then you're fine.A perfect reason against designing something to be critical on the parts used. Like hFE ("suicide") versus emitter degeneration bias, to use a simple and popular case.Tim

author: floobydust
author_rank: Super Contributor
timestamp: October 19, 2017, 05:28:11 am
content: 1970's Tektronix tested and ranked all transistors and diodes; ranked by hFE, leakage current, avalanche voltage etc.Some manufacturers have crap datasheets and I buy from those that have good information, like On-Semi and NXP.Diodes Inc datasheets are terrible, missing tons of the usual specs. If a spec is absent, it's not tested so buyer beware.Example BC846A datasheet:Infineon 13 pages, 17 graphsFairchild 7 pages, 17 graphsTaiwan Semi 6 pages, 12 graphsOn-Semi 13 pages, 10 graphs ea.NXP 15 pages, 8 graphsDiodes Inc 7 pages, 3 graphs

author: Vtile
author_rank: Super Contributor
timestamp: October 19, 2017, 09:35:03 am
content: Is there a general rule of thumb for high(ish) voltage (ie. 100V to 140V range), but low leakage (Vce and maybe Vbe) BJT transistor type. ...Or is the higher voltage the rule of thumb to find lower leakage type.** Low leakage, <15nA ****When searching that transistor model***PS. If we still try to stay on "general purpose" category.

author: David Hess
author_rank: Super Contributor
timestamp: October 19, 2017, 01:09:15 pm
content: Quote from: Vtile on October 19, 2017, 09:35:03 amLeakage depends more on area, construction, processing, and temperature than voltage rating. For small signal transistors, it is only tested down to a level of 10s of nanoamps because that covers almost all applications and a more sensitive test would take longer.Voltage rating has more of an effect on recovery time.A thorough search will turn up transistors tested down to 10 nanoamps but I think of low leakage as 10 picoamps and lower which I have had no trouble finding in common parts like the 2N3904.

author: exe
author_rank: Unknown
timestamp: October 19, 2017, 01:36:20 pm
content: Quote from: T3sl4co1l on October 19, 2017, 04:58:41 amThe problem is many parameters are not specified, or only "typical" values are specified. Or how this parameters change with temperature, supply voltage, etc.

author: Vtile
author_rank: Super Contributor
timestamp: October 19, 2017, 02:18:37 pm
content: Quote from: David Hess on October 19, 2017, 01:09:15 pmMakes sense, thx. PS. I just noticed that at least some types of PN2222 are "rated" to 10nA Icbo max. at 25 deg.C. I'm more and more confident the bulk box of cheap as dirt (they are sand after all) parts (from reputable source) is right way to go formostall non-production hobbyist needs, most critical feature seems to be that you have the stock pile to pick from.It would be interesting to know if the garden variety actually do have different internals between models or are they actually just from one outcome from a machine and then sorted to meet differentkeyspecifications of garden variety part numbers. I wouldn't be too surprised (without having even general knowledge of semiconductor production) if this would be the case looking at how close the specks are in many parts.

author: David Hess
author_rank: Super Contributor
timestamp: October 19, 2017, 09:00:25 pm
content: Quote from: Vtile on October 19, 2017, 02:18:37 pmIt is common for one design to result in multiple part numbers and it happens with some ICs as well. Bipolar transistors are often graded for Vce and of course hfe to be divided into different part numbers. Some power MOSFETs are graded for Vds like Vce in bipolars. Besides things like offset voltage, bias current, and offset voltage drift, many old bipolar operational amplifiers were also graded into 28, 36 and 44 volt versions.And as mentioned earlier, some part numbers like the 2N3055 become a dumping ground for other parts which did not meet their intended specifications.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 19, 2017, 09:10:05 pm
content: I recall measuring a random 2N4401 in the low nA. It was a cold day, YMMV.If it's not on the datasheet, you have to test it yourself. Fine for breadboarding, or small run test equipment, say. Not so great for production.Again, jellybeans aren't tested for leakage, because it's slow -- expensive to test! There may be special-purpose designations which are, but they'll be expensive for that reason (and also the much smaller quantity of product being moved).Tim

author: Cerebus
author_rank: Super Contributor
timestamp: October 19, 2017, 09:30:26 pm
content: Quote from: T3sl4co1l on October 19, 2017, 09:10:05 pmBut doable nevertheless. The HP/Agilent/Keysight 34401A had a selected JFET* in the input amplifier and they made 25,000 a year of the suckers.*Q104, selected for a given range of VGSat an IDSof 1.36 mA.

author: SeanB
author_rank: Super Contributor
timestamp: October 20, 2017, 08:38:34 pm
content: Simple reason they do not change the spec is because the specification is for a MINIMUM requirement, that the transistor is guaranteed to meet when manufactured. That your device you bought is so much better is moot, you are buying one that gets that minimum spec exceeded.As to different devices getting different part numbers, randomly opened the NS small signal transistor book, and looked at process 63, PNP medium power device. There the same die can be put into 5 different packages, and be variously a 2N2905A, 2N2907A, 2N4403, 2N3702, 2N3645 or a 2N4143.Then you get the interesting ones, like process 59, a dual small signal MOSFET in TO99 package that is a whole series of FM3954 or FM1100 series.Then process 1, which is graded into various power parts, including the venerable 2N3055.Fun one is a MPQ6502, which is not a processor.

author: Cerebus
author_rank: Super Contributor
timestamp: October 20, 2017, 09:17:59 pm
content: Wouldn't life be easier if, instead of the JEDEC/whatever part numbering scheme evolving, we'd had something like the National book. Here's the set of dies, here's the parameters we actually test and here's the bins we put them into and the part numbers for those bins.I still find myself going to the (defunct) National databook to find a suitable part from time to time just because the layout by process makes it easier to navigate.

author: Lassivv
author_rank: Contributor
timestamp: October 29, 2017, 07:55:26 am
content: Try to buy some good "middle-way" mosfets on my stock.Normally i drive something 12-24vdc (leds, motor etc) with mosfets (90% different leds).Now i have stock- ULN2003- IRFZ44N- Here maybe need one more cheap option (trough hole) model.Then i need some SMD models. (use many hours on Mouser find and Nexperia chips seems interesting)cheaper, not that good RDShttps://www.mouser.fi/ProductDetail/Nexperia/PSMN7R5-30YLDX/little pricier, better RDShttps://www.mouser.fi/ProductDetail/Nexperia/PSMN2R4-30MLDX/Find so many different voltage/Ampere/RDS models and same footprint. Quite cheap parts and because Mouser/Farnell i think they are good quality and not any fakes or something like that.Every hints/tips are welcome. Need one more good/cheap throught hole model (like mosfets more than transistors). And what you think Nexperia chips.

author: David Hess
author_rank: Super Contributor
timestamp: October 29, 2017, 01:00:39 pm
content: Quote from: Cerebus on October 20, 2017, 09:17:59 pmThat would be nice and I use the old National Discrete databook for the same thing. For instance it is especially annoying with On's (and now Fairchild's since they bought them) product portfolio because there are parts I know exist, like fast saturated switches, which cannot be searched for. Transistors built using different processes like perforated and ring emitter structures should be labeled. This would have helped distinguish all the variations of the 2N3055.The same thing occurs with Texas Instruments and their various linear parts. They often do not include even simplified or equivalent schematics so it is not always apparent how the input and output circuits work which is important in some applications.I wonder what advantage the various manufacturer's think is provided by withholding this information.

author: Wolfgang
author_rank: Super Contributor
timestamp: December 28, 2018, 09:57:10 pm
content: Quote from: David Hess on October 14, 2017, 02:26:59 amFor HV work if often use MPSA44 and MPSA94 (400V) or MJE340 and MJE350. Medium speed, but reliable.

author: vk6zgo
author_rank: Super Contributor
timestamp: December 31, 2018, 02:28:03 am
content: Quote from: Vtile on October 14, 2017, 10:38:43 amNo, as the distinctions are well known, & you can get charts showing the division of the spectrum.The actual terms are as they are for historical reasons, & changing them now would be even more confusing.

author: vk6zgo
author_rank: Super Contributor
timestamp: December 31, 2018, 02:49:21 am
content: Back in the day, a supplier in my home city used to have a "lolly jar" ( candy jar to NA folk) containing a huge quantity of "cleanskin" unmarked NPN silicon transistors, which they sold for a few cents eachThey had the same package as the BC107, BC108 series, & would work in most of the same circuits which used those.We called them "BC10?" Transistors.In a repair situation, you will often find manufacturers will use the same device in both a critical & non-critical position.If the one in the critical spot dies, steal the non-critical one, & replace it in the non-critical spot with a generic transistor.Another trick is to have a look at what device some other company uses in a similar position.Sometimes, it is cheaper & has better specs.I replaced the horizontal output transistors in a lot of Sony 27" picture monitors with Philips BU208D devices with universally good results.Although Sony were good with parts supply, BU208D transistors were cheaper & available "anywhere"..

author: Brumby
author_rank: Unknown
timestamp: December 31, 2018, 07:45:56 am
content: Let's get in early for the future....!How about:Band nameAbbreviationITU band numberFrequencyWavelengthExtremely low frequencyELF13–30 Hz100,000–10,000 kmSuper low frequencySLF230–300 Hz10,000–1,000 kmUltra low frequencyULF3300–3,000 Hz1,000–100 kmVery low frequencyVLF43–30 kHz100–10 kmLow frequencyLF530–300 kHz10–1 kmMedium frequencyMF6300–3,000 kHz1,000–100 mHigh frequencyHF73–30 MHz100–10 mVery high frequencyVHF830–300 MHz10–1 mUltra high frequencyUHF9300–3,000 MHz1–0.1 mSuper high frequencySHF103–30 GHz100–10 mmExtremely high frequencyEHF1130–300 GHz10–1 mmTremendously high frequencyTHF12300–3,000 GHz1–0.1 mmRidiculously high frequencyRHF3–30 THz100–10 μmFantastically high frequencyF***ing high frequencyFHF30–300 THz10–1 μmObscenely high frequency** Optically high frequencyOHF300–3,000 THz1–0.1 μmPreposterously high frequencyPHF3–30 PHz100–10 nm** Covers visible light

author: spec
author_rank: Frequent Contributor
timestamp: December 31, 2018, 08:29:01 am
content: Quote from: Vtile on October 12, 2017, 11:28:44 pmHi VtileThis is my list of complementary goto jellybean BJTs:BC546C/BC556C : 65V, 100mA, 500mW, TO92 (plus clip-on heat sinks)BC337-40/BC327-40 : 45V, 500mA, 625mW, TO92 (plus clip-on heat sinks)TIP41C/TIP42C : 100V, 6A, 65W, 2degCW, 150degC TO220 (plus clip-on heat sinks and heatsink mounting kits)TIP35C/TIP36C : 100V, 25A, 125W, 1degCW, 150degC TO247 (plus clip-on heat sinks and heatsink mounting kits)2N3055/MJ2955 : 70V, 15A, 115W, 1.52degCW, 200degC, TO3 (You just have to have these old work-horses, but only the revised HF type [epitaxial base])The clip-on heat sinks are handy, to get you out of the situations where you want the performance characteristics of a smaller transistor, but slightly exceed the bare case dissipation (BC337/BC327 especially). For the bigger transistors the heatsink clips often eliminate the need for a full-blown heatsink.