BC547 Transistor - Page 1
Forum section: electronics / beginners

author: Munyua44
author_rank: Contributor
timestamp: January 17, 2022, 04:56:24 am
content: I have a PCB with BC547 transistor that has blown off. In my local store, they don't have the BC547 transistor yet i need this job complete immediately. Advice on the BC547 equivalent transistor that i should use instead.

author: bob91343
author_rank: Super Contributor
timestamp: January 17, 2022, 05:57:04 am
content: https://components101.com/transistors/bc547-transistor-pinout-datasheet

author: DavidAlfa
author_rank: Super Contributor
timestamp: January 17, 2022, 07:29:51 am
content: BC548, 2N2222, 2N3904, BC337, BC945... probably can replace it.

author: Zero999
author_rank: Super Contributor
timestamp: January 17, 2022, 10:34:11 am
content: Just make sure the replacement has a high enough voltage/current ratingThe BC546/547/548/549/550 are all pretty similar, but the BC547 has a voltage rating of 45V. If in doubt, get the BC550 or BC546, but as mentioned above, it's probably not critical and any small transistor will work.https://www.sparkfun.com/datasheets/Components/BC546.pdf

author: rob77
author_rank: Super Contributor
timestamp: January 17, 2022, 12:02:02 pm
content: also check the gain of the replacement transistor (Hfe,H21e,beta) ... in some case too much gain or not enough gain can cause problems, but that heavily depends on the circuit itself.

author: Zero999
author_rank: Super Contributor
timestamp: January 17, 2022, 01:21:40 pm
content: hFEis a good function test, but if the circuit is properly designed, then it shouldn't matter what it is. The data sheet specifies 110 to 800, but that only applies at a junction temperature of 25°C, VCE= 5 and IC= 2mA. It might be different under different conditions. It's just a rough guide.TLDR: the transistor will typically have an hFEof around 200 on a transistor checker and if it's much below 100, then it's probably bad. Otherwise it's good and the circuit should work with it.

author: Terry Bites
author_rank: Super Contributor
timestamp: January 17, 2022, 04:02:24 pm
content: Here are a few candidates:https://uk.farnell.com/w/c/semiconductors-discretes/transistors/bipolar-transistors/single-bipolar-junction-transistors-bjt?transistor-polarity=npn&collector-emitter-voltage-v-br-ceo=40v|45v|50v|60v|65v&dc-collector-current=30ma|50ma|100ma|200ma|300ma|400ma|500ma|600ma|700ma|800ma|900ma|999ma|1a&power-dissipation-pd=400mw|450mw|500mw|540mw|550mw|575mw|590mw|600mw|625mw|640mw|650mw|700mw|710mw|750mw|770mw|800mw|810mw|870mw|900mw|940mw|1w&transistor-mounting=through-hole&no-of-pins=3pins&dc-current-gain-hfe=2hfe|5hfe|10hfe|12hfe|15hfe|20hfe|25hfe|30hfe|35hfe|40hfe|50hfe|60hfe|63hfe|75hfe|85hfe|100hfe|110hfe|120hfe|135hfe|140hfe|150hfe|160hfe|170hfe|200hfe&st=npn&min_max=f1000905Anyone remember TUP and TUN?

author: rob77
author_rank: Super Contributor
timestamp: January 17, 2022, 08:40:17 pm
content: Quote from: Zero999 on January 17, 2022, 01:21:40 pmare you trying to tell me if i replace a transistor with Hfe 100 with one with Hfe 400 that the circuit will function as expected regardless of the nature of the circuit ? for example the quiescent collector current in a class A amplifier will not change if i use a transistor with different Hfe ? .. common...sure, if the transistor is used as a switch, then it's in driven into deep saturation and the gain of the transistor is not that important..

author: magic
author_rank: Super Contributor
timestamp: January 17, 2022, 08:57:25 pm
content: It surely is possible to make something that depends on β, like it is possible to bias a simple common emitter stage (is this what you meant?) independently of β, using base resistive divider and an emitter resistor.Anything mass produced tends to avoid β dependence to eliminate selection and tweaking costs

author: rob77
author_rank: Super Contributor
timestamp: January 17, 2022, 09:04:48 pm
content: Quote from: magic on January 17, 2022, 08:57:25 pmsure, but no-one seen the OP's schematic, therefore no-one knows for sure and that's why i mentioned that gain needs to be checked as well when choosing a replacement.

author: MK14
author_rank: Super Contributor
timestamp: January 17, 2022, 09:06:44 pm
content: Quote from: rob77 on January 17, 2022, 09:04:48 pmDon't forget, the OPs been banned, I think it is because they are a spammer. E.g. This question (OP) has been spammed in a number of different places, and may not be a genuine question.

author: rpiloverbd
author_rank: Regular Contributor
timestamp: January 21, 2022, 01:37:47 pm
content: This article may help you:https://www.quora.com/What-are-substitutes-for-BC547-transistors