are these transistors interchangeable, also i dont know much about transistors  - Page 1
Forum section: electronics / beginners

author: nus
author_rank: Contributor
timestamp: November 22, 2017, 06:59:59 pm
content: are these interchangeable?they are for a voltage controlled oscillator, it has a tempco resistor running over the top of ithttp://www.farnell.com/datasheets/682969.pdfhttp://www.farnell.com/datasheets/661087.pdfhttp://au.element14.com/w/c/semiconductors-discretes/transistors/bipolar-transistors/bipolar-junction-transistor-arrays-bjt/prl/results?transistor-polarity=dual-pnp&collector-emitter-voltage-v-br-ceo=neg45v&sort=P_ATT_BASE_VALUE_1000905_EN_GB|1they seem almost identical apart from Power Dissipation Pd which I'm worried about because of the tempcoalso what are some of the functions of transistors, I think they can be used as switches, voltage regulators, and voltage amplifiers. is this all they are used for? they kinda confuse me a bit.

author: Zero999
author_rank: Super Contributor
timestamp: November 22, 2017, 07:41:15 pm
content: They look similar to me. The packages are different, which will be an issue, if you're replacing them on an existing piece of equipment, or have already designed the PCB.Matched transistors are used in applications, requiring two identical transistors, such as in the input stage of a differential amplifier. Discrete matched pairs aren't used so much nowadays, as they used to be, as the main application has been replaced with op-amp ICs.

author: Vtile
author_rank: Super Contributor
timestamp: November 22, 2017, 10:56:37 pm
content: Quote from: nus on November 22, 2017, 06:59:59 pmThere is many main types of transistors and transistor technologies. Point contact transistors (obsolete), Germanium transistors (obsolete), silicon transistor (majority today). Then there is at least BJTs, FETs, IGBTs. FETs do divide to two common main types IGFETs (Insulated Gate Field Effect Transistor) and JFETs where IGFETs are usually referred as MOSFET (by first common sub-type). JFETs are somewhat subsided by IGFETs, but still serve in special purposes mainly in high end analog applications. Wikipedia will open up these acronyms.What usage is concerned transistors are used for pretty much for anything and also most ICs are build from transistors (IGFET technologies). The two main types of usage are voltage controlled current source (FETs) and current controlled current source (BJTs). As these suggest one do have current and another do have voltage as a dominant property of the control mechanism. So as almost any IC is build with combination of transistors, it suggest that transistors can also be used as current sources, diodes, comparators, current amplifiers, power amplifier and so on.Matched pairs were commonly used as a differential amplifiers, you can search more information with that keyword.A short description, please note that transistors aren't my field of expertise so above might have some minor mistakes.

author: nus
author_rank: Contributor
timestamp: November 24, 2017, 06:05:16 am
content: half the reason for me wanting to change it is because there was an error on the board, this package actually fits it better, plus I can find it on aliexpress for $7 for 50

author: nus
author_rank: Contributor
timestamp: November 24, 2017, 06:09:33 am
content: also cheers dude^^