Exact replacement for Transistor 2sc1845

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Dear Quasi,

As a designer of Actrk600, what replacement would you suggest for 2sc1845 transistor as it is not available here in India. I do not want to take any chance to damage my MOSFET's and other transistors in Actrk600 amplifier I am going to build. Please help.
 
BC546

Will fit, but leads may be in different order....download datasheet of both transistors and compare base, emitter and colector lead's position.

This one is an Universal NPN replacement transistor that fit almost everywhere...check only your supply voltage that cannot be higher than 40 volts positive and 40 volts negative..... or the spot you gonna use it must have less than 80 volts from colector to emitter in stand by position and if VAS then you must have check if your swing of voltage there is less than 80 volts.

If you do not feel safe to use, or if you believe your know how is not that big..them do not replace.... search for the correct part.

It is not an exact replacement, but the most important parameters are matched or good enough to operate in a safe way....if you want an exact precise substitute, them try the KSC our friend told you...this is an exact version of your transistor (almost exact).

I have used BC546, as replacement in thousands amplifiers....i have never faced troubles

regards,

Carlos
 

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To replace a transistor with a substitute

You need only to answer these basic questions:

- Is the replacement unit the same polarity? (NPN or PNP)

- Are the leads in the same position?

- About power, what is the power dissipated in the original, does it match?

- About voltage swing from colector to emitter, does the replacement unit fit?

- About colector current at 25 degrées celsius... does it match?

- To audio frequency you must not worry about the maximum frequency

What i mean with match?... original transistor real circuit current cannot be higher than the elected replacement unit, original transistor real circuit power cannot be higher than the elected replacement unit, original transistor real circuit voltage swing cannot be bigger than the elected replacement unit.

Gain range, electrode capacitance and other specifications may not harm your circuit as modern biasing tolerates a lot of mismatch.

If the elected replacement unit is within the range of these specifications, power, current and voltage...then solder the new one in place.



regards,

Carlos
 
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BC5xx are cbe pin out
2sa/c and ksa/c are bce, except To126 which are ecb

BC549 and BC550 are low noise. The spec is not quite as low as 2sc1845, but in circuit they are often just as quiet.
BC546 is almost as quiet according to the spec. But I use bc546c as the input LTP and cannot measure any difference in noise from a bc550c.
 
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