Other type of transistor use for audio (amplification or power safety system)?

[guitar89]

I scavenge an old CRT monitor, and saw some transistor which i'm thinking to reuse, so my question :
CAN I use transistor of other type (video) to use as audio or other application like power switching/regulation ? My example here is :
C5404 from Toshiba, the datasheet is as follow : http://pdf.chinaicmart.com/88888/20083794333540.pdf
This is use for high speed switching application in TV, is it possible to make it into power shutoff or soft starting transistor ? or even for audio amplification usage also no problem ?

[Mooly]

The 2SC5404 is a line output transistor or horizontal output as sometimes called. These types were common in the days of CRT TV's , types like BU208, BU508 S2000AF BUT11 etc etc.

Generally these are not suited to linear audio amps as the main problem is that the gain is low. They are really intended to be driven either fully on or fully off. That said they are just silicon NPN devices, it's just that the properties are optimised for switching.

Small signal transistors and video output transistors are often overlooked for audio and they can be an excellent choice in some applications having low junction capacitance and good HF characteristics.

[Leon08]

I think you can use them for audio, but they probably will produce more noise or distortion.

[guitar89]

guess we cannot use it as audio amplification..... NVM
then is it a good choice to use it only for switching purpose of my amplifier ?
Such as soft starting and for safety tripping (over current tripping protection) ? since they are excellent in FAST switching

[Mooly]

You would have to determine its suitability making sure that on start up the devices' SOAR (safe operating area) was not compromised.

[guitar89]

haha, then guess transistor scavenged is hard to apply for audio and power unit : (
except we scavenge from other audio unit.(amplifier)

[Leon08]

It's not that hard if you know what you are doing.All transistors work basicly in the same way.You need only the datasheet to see the specs and some knowlege about it.

[guitar89]

haha, yeah, just same npn and pnp, but they have specified function/special, which they do good in them. I also agree with you, if you have knowledge and some spec, it is not too difficult to find a suitable application to use it.
Leon, you have any article/tutorial about how to utilise transistor or how to fully understand the specification ? (having problem understand them) in order to do those jobs ?

[Mooly]

This is has become a bit of a classic, if you can get hold of a copy. Library maybe ?

The Art of Electronics - Wikipedia, the free encyclopedia

I'm afraid a lot of knowledge is hard won through study and experience and in my case it being the day job for many years... if there is anything in particular you want help with or don't understand then maybe we can help

[guitar89]

hahha, yeah ! Unlike IC, transistor datasheet doesn't provide application mode circuit (well...... understandable) and the transistor gain is variable (in a range), so the first thing is that i dunno how to SET the transistor's gain in a circuit. (been longing to learn that)

I also saw some article about how to make an switching device with transistor (act like relay), but can't fully understand its operation.

Also about the operation and example of an transistor work as high speed switching (well... over current protection, etc) as a protective member (maybe more useful in audio amp)