Timeline for finding suitable substitute for 2n3904 transistor
Current License: CC BY-SA 3.0
24 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Oct 13, 2016 at 16:47 | answer | added | Bruce Abbott | timeline score: 4 | |
| Oct 13, 2016 at 16:18 | answer | added | Phil Frost | timeline score: 3 | |
| Oct 13, 2016 at 15:39 | answer | added | D.A.S. | timeline score: 0 | |
| Oct 13, 2016 at 15:16 | comment | added | Sredni Vashtar | 2n2907 is PNP, so... no, unless you want to redesign the circuit. The other one should do, but you might have to trim some values. | |
| Oct 13, 2016 at 14:48 | comment | added | vaidehi | one more thing i want to know that can i use a 2n2222,2n2907,2n5088 for this? | |
| Oct 13, 2016 at 14:40 | comment | added | vaidehi | ok....thanks FakeMoustache for your help.Actually i am in 9 standard and i am making this project for my science fair.....thankz for ur help. | |
| Oct 13, 2016 at 14:39 | comment | added | Bimpelrekkie | Oh, and do use testpersons which sweat a lot when they lie otherwise this thing is never going to work. | |
| Oct 13, 2016 at 14:38 | comment | added | Bimpelrekkie | I added the circuit into your question. My conclusion: any of the suggested transistors will do the job. If you're unsure or want to check then I think the current amplification (Hfe or beta) is the most important parameter. And for the 2n3904 beta isn't even that high. I'd use the BC547 anytime for a job like this. | |
| Oct 13, 2016 at 14:34 | history | edited | Bimpelrekkie | CC BY-SA 3.0 |
added 130 characters in body
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| Oct 13, 2016 at 14:32 | comment | added | vaidehi | google.co.in/… | |
| Oct 13, 2016 at 14:30 | comment | added | D.A.S. | I like the zombie doll but your link is not direct | |
| Oct 13, 2016 at 14:26 | comment | added | vaidehi | yes but it can be a voice reader also instead of lie detector and only the led should light up.........cdn.instructables.com/F4E/WPH0/FRML73D7/… | |
| Oct 13, 2016 at 14:25 | comment | added | D.A.S. | nothing is perfect unless all context of application details are shown, but "lie detector" needs to amplify est.~50k Ohms down to est.5 Ohms to switch on LED , so gain overall est.~ 10,000 , normally excess gain is needed to regulate gain based on R ratios | |
| Oct 13, 2016 at 14:24 | comment | added | vaidehi | a perfect replacement is not needed, the condition is that the led of the detector should light up with the help of sensations so,i want a replacement which can do the job. | |
| Oct 13, 2016 at 14:21 | comment | added | Bimpelrekkie | Forget about the "perfect" replacement, often that is not needed. I'd say that a circuit which would only work with a 2n3904 (or a "perfect" replacement) is a very bad design. | |
| Oct 13, 2016 at 14:21 | comment | added | vaidehi | a 2n5088?may be!!can it be replaced by a 2n3904? | |
| Oct 13, 2016 at 14:18 | comment | added | D.A.S. | can you get a 2N5088? or a BC547C (not B, C has 2xmore gain than B) For high current gain application and no schematic.. that's my best guess | |
| Oct 13, 2016 at 14:18 | comment | added | Bimpelrekkie | The 2n3904 is very generic transistor and used everywhere. Since you probably cannot yet judge which parameters are important, searching for a replacement is like searching for a needle in a haystack. You'd do much better showing the schematic in which it is used so that we can judge what other transistor would also do the job. My bet is a BC547 will do perfectly fine, especially when the 2n3904 is just switchin something on/off, almost any generic transistor will do. | |
| Oct 13, 2016 at 14:16 | comment | added | vaidehi | Thanks, it helps a lot but can u also suggest me a good match?As am not that qualified am still a school girl if u would help me it would help me a lot. | |
| Oct 13, 2016 at 14:10 | comment | added | WhatRoughBeast | Go look up a data sheet for the 2N3904. Notice that most values (leakage, hfe, etc) have a range of possible values. So there is no such thing as a "perfect" replacement - only one which is generally the same. Now look at the data sheets of the potential replacements, and pick one with a good match. | |
| Oct 13, 2016 at 13:56 | comment | added | vaidehi | not really but the thing is that whenever i use that lie detector or the voice reader the light should light up.It includes 10K resister 47K resister 470 resister 1M resister x2 and 47K& VR and x3 2n3904 transistors. | |
| Oct 13, 2016 at 13:42 | review | First posts | |||
| Oct 13, 2016 at 16:23 | |||||
| Oct 13, 2016 at 13:40 | comment | added | Ignacio Vazquez-Abrams | Do you know which characteristics of the transistor are important? | |
| Oct 13, 2016 at 13:37 | history | asked | vaidehi | CC BY-SA 3.0 |
