Using the 4049 as a buffer?

[WaveshapeIllusions]

I'm wondering if you can use those CMOS inverters as a simple buffer. I've seen them used as distortion devices relatively often, but what about clean?

If not, are there any ICs out there that consist of just input/output pins for multiple devices? I recall seeing a chip somewhere that was basically a few MOSFETs.

I suppose I could use opamps too,  but I'm looking at making a compact multi-stage phaser and would prefer to use as few chips as possible.

[armdnrdy]

See ADA Flanger threads. The 4049 is used to buffer the clock lines.

[R.G.]

You can use *unbuffered* CMOS inverters like the 4049 and 4069 as inverters by using equal-value input and feedback resistors. They are not very "ideal" buffers in that they will have some amount of distortion, not near-zero like opamps; they may be noisy, and may pull a lot of current when biased into the middle of their power supply range. Plus, if you're wanting to buffer and not invert, you have the issue of the signal being inverted, and maybe needing two sections per signal to get back buffered but not inverted.

For compactness, it's hard to beat TO-92 darlingtons. If the incoming signal has a DC level on it, as it usually does, the darlington needs only a resistor to ground to buffer the signal. The bigger advantage is that a single buffer like this can be put next to the signals it's buffering instead of having signals routed over to the buffer IC and back to where they're needed. The board layout is generally easier and more compact. For this same reason, I prefer dual opamps over quads.

I often use pin count as a metric for compactness. A hex inverter will be 14 or 16 pins, and will use two resistors per section at least, or another 24 pins. The count is six pins per inverter/buffer section plus a power and a ground. The separate darlington is three pins for the device and two for the emitter resistor, and it's much more flexible for layout.

The only multiple in/out chips above quad opamps I can think of are transistor arrays, perhaps including the ULN2003 and others in its family (which will be inverting, all the emitters are grounded); graphic equalizer chips with six or seven transistors or opamps inside for the gyrators.

Have you considered using Single Inline Packaged dual opamps? These are a 16 pin chip body, but with pins only on one side. You get a dual opamp, but it takes up less board space than a flat DIP.

@armdnrdy - those are digital buffers, in the sense of "More current!". I don't think they're analog buffers.

[WaveshapeIllusions]

Thsnks RG. A trandiator array seems like exactly what I was looking for. Didn't know the name though. Searching for transistor IC is rather vague.

The darlingtons seem like a good idea too though. A layout that can be flexible is nice, I have spent a decent chunk of time trying to fit all the components near the chip on perf. I assume darlingtons are much easier to find too, which is a major benefit. Whenever I figure it out I'll have to post the design.