tayda npn transistor array chip question

[reverberation66]

    so on tayda's new products section they have a chip called a CA-3046 general purpose npn transistor array.  it's basically just multiple transistors on one chip.  I was thinking to myself what a cool little chip for some sort of fuzz circuit.   It says on page 2 of the dataseet: http://www.taydaelectronics.com/datasheets/A-918.pdf   that pin 13 must be connected to the most negative point in the external circuit for normal transistor action.  My question is what does "the most negative point in the external circuit" mean?  is this just an offboard ground or does it mean something else?

[electrosonic]

I have wondered about this too. Do you have to "waste" a transistor to ground pin 13 if you do not have the need for a grounded emitter transistor?

Andrew.

[amptramp]

The transistors are built on a junction-isolated substrate, so pin 13 has to be at the lowest voltage.  By junction isolated, they mean the circuit is successive depositions of doping material on silicon with all the elements of the transistors (probably only the collectors) being isolated by reverse-biasing the substrate with respect to the rest of the transistor.  If the substrate is higher than any of the other items by a diode drop, it will conduct and short the collectors together.

[Pyr0]

Well for our applications where we are using it in a 9v powered pedal, just tie it to ground and don't worry about it.

[Quackzed]

sweet thats so cool, a little transistor array. god i'm such a nerd.
wait, whats that differential pair crap... 14 pin? why not a 16 pin?!? ok i'm nitpicking... its still cool.
i just had a thought. we should get these guys to give us samples of some of their new stuff and maybee promote a competition or 2.
you know, here are 10 samples of our neat new chip so you can let ten people have 1 each and have a competition to design a circuit with 'em.
promotes people buying 'em in the future... some one of us could probably work that... 
maybee not a big heavy prizey competition, just a little push to design something new...

[psychedelicfish]

Slight change of topic, but how about something like this for a simple fuzz/distortion:

slightly pointless, i know, but why not

[electrosonic]

For what its worth, you can buy the LM3046 at Electronics Goldmine (surplus NOS) for $0.49 versus for the $1.10 for the CA3046 (new) at tayda. I am pretty sure they are equivalent.

Andrew.

[PRR]

> new products section they have a chip called a CA-3046

NEW?? The base chip is older than many folks here. 1972?

All that's new is that the 3046 has been retired more times than the Rolling Stones, and won't go away.

[greaser_au]

the CA3046 is used as the channel switch in the (80's vintage) Marshall JCM800 channel switching amps (2205/2210/4205/4210 - the single input ones)...

david

[electrosonic]

Its actually Retro Channel's proprietory chipset 
There was a pretty messy discussion on the other forum about it.


Andrew.

[frequencycentral]

Used in Moog filters! Cool.

[kupervaser]

Way Huge's Swollen pickle (the original unit) utilizes a quad array chip, basically you could build any big muff with it.

[alparent]

But why would you get a 1.10$ chip to replace 10 cents worth of transistors?

Just 'cause it's defferent?

If they where matched pairs of JFET then that would be a different story.

[digi2t]

Three words...

Tau Pipe Phaser.

There`s also LM394, in an eight pin package. A pair of super matched transistors. Don`t know if it`s any use for a fuzz type circuit. Maybe for the octave section of a Superfuzz?

[armdnrdy]

But why would you get a 1.10$ chip to replace 10 cents worth of transistors?

Just 'cause it's defferent?

If they where matched pairs of JFET then that would be a different story.

Extracted from the data sheet.

they provide the very significant inherent integrated circuit
advantages of close electrical and thermal matching.