The CA3046 General Purpose NPN Transistor Array IC

[TomCarlos]

In a thread related to Marshall amps (Troubleshooting and solving signal noise on a 1989 JCM 800 2205), the CA3046 IC was mentioned. It is used for channel switching. This seems to be identical to the LM3046 and LM3086.

This IC appears to contain five NPN transistors (and nothing else in the circuitry). Due to the IC size, I would assume the transistor array components are low voltage and low noise. I guess the idea was to put five transistors under one roof, with a common substrate as a space saving device? Maybe it was also done if "matching" was a concern, especially if Q1 and Q2 are wired up as a differential pair?

I also read somewhere this IC is getting hard to find?

So if space was NOT an issue, could someone abandon the IC and then install 5 small transistors? Maybe a 2N3904, MPSA09, 2N2484, 2N2222, 2N5088, or 2N5210?




CA3046.pdf

LM3086.pdf

2N3904.PDF

[The Dude]

Sure, you could. The advantage of the chip is that transistors within are closely matched (as you mention). And, since in the same substrate, they share the same thermal tracking/effects. Critical in some circuits, but not so much in others. You'd have to match transistors yourself using separate devices instead of the chip in circuits where it mattered. The chip is just more practical in some instances.

[TomCarlos]

Sure, you could. The advantage of the chip is that transistors within are closely matched (as you mention). And, since in the same substrate, they share the same thermal tracking/effects. Critical in some circuits, but not so much in others. You'd have to match transistors yourself using separate devices instead of the chip in circuits where it mattered. The chip is just more practical in some instances.

Thanks for confirming!

[drewl]

I made up a chip by mounting the transistors on an IC socket.

Of course shortly after I found several tubes of the 3046 at work.