Can 4049 replace 4009 in Bad Stone?

[B Tremblay]

Can a 4049UBE replace a 4009A/BE in an E-H Bad Stone phase shifter?

I found a datasheet for the 4049 that says it is the preferred replacement for the 4009 in buffer applications, but does this apply to the Bad Stone?

Relevant Links:

4009 datasheet

4049 datasheet

Bad Stone schematic

[Paul Perry (Frostwave)]

There is a warning in the CMOS handbook that the 4069 'may' overheat in linear applications, FWIW. But I don't know how 'alike' the internals are.

[B Tremblay]

There is a warning in the CMOS handbook that the 4069 'may' overheat in linear applications

Do you mean 4049?

My limited understanding (which may be incorrect) is that the 4009 is used as a FET array.  Does buffering play a role when the IC is used in this manner?

[gez]

Hi B, I've just had a quick glance and each gate of the chip is functioning as a variable resistor.  The same thing can be done with 4049s but whether it could be used as a direct replacement (pin for pin) I don't know, I'd have to have a look in more detail (might have some time tonight)

If you just meant could you use a 4049 with a bit of rejigging to do the same job, then I don't see why not.

[B Tremblay]

whether it could be used as a direct replacement (pin for pin) I don't know

That's what I'd like to do, a direct sub.  Thanks in advance for your efforts.

[gez]

I’ve had a better look and I’d say it should be ok as a pin-for-pin replacement.  As far as I can tell, with Vcc & Vdd connected together, then tied to all the inputs, all the upper devices of the 4009 are disabled, and out of the two lower devices only the second n-channel is conducting.  Seeing as a 4049 wired the same would give you one device per gate too, it should give the same performance (though I can't help feeling that a trimpot somewhere or other would help combat any differences between chips).

My only worry would be differences in diode protection networks (someone more knowledgeable would be able to help here).  I only mention this as earlier on in the year I had problems with a 4007 made by ST - it didn’t like being wired up a certain way, though other 4007s were ok (I could only conclude that the protection network was different).  

Anyway, probably best to socket it and give it a whirl.  If smoke starts pouring out all over the place, resulting in the burning down of your property, then I’ll conveniently use the edit function and delete this post…no-one will ever know!

[B Tremblay]

Actually, the original 4009 is socketed, so I was wondering if I could just pop the 4049 in there.  I may try it out (if I'm sufficiently motivated), but for now my inquisitive nature is satisfied.  No sense in fixing something that isn't broken.  Or breaking it, for that matter!

I really appreciate your time and attention.

[B Tremblay]

Four months later (nearly to the day) and I have an answer.

While installing a DPDT for true bypass in the Bad Stone, I decided to take the plunge and try a 4049UBE in the 4009 socket.  It works!

There is a slight difference in the sweep - the 4049 spends a bit longer in the "down" portion - but sounds exactly the same otherwise.

I realize that this isn't exactly earth-shattering news, but I wanted it to be publicly recorded.

[gez]

Phew!

[B Tremblay]

Phew!

Finally, an end to your sleepless nights!

[gez]

Finally, an end to your sleepless nights!

If only!