Re: Analog multiplexor help

Chris skrev:
On Apr 17, 2:20 pm, Jan Nielsen
<nos...@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Hi, Jan. I'd guess you're talking about the 74HC4051 mentioned in an
earlier post.
Yes

However, and I don't believe it directly says this on this datasheet,
if all your input signals are between the digital supply rails (like
your LM35), you can tie Vee to GND and get away without a dual supply.
For a test the 8in/out puts are connected to a LED and the input/output is connected to VDC+.

So by setting the 3 signal pins I should be able to control which LED is on, right ?

The signal to the pins is from a picaxe, so its probaly around 4.7V and the supply is about 4.7V too.

One thing it does say pretty clearly is that the "E" is an enable, and
it has to be tied low to get it to work. This can be neat if you want
to parallel the single multiplexed pins and, say, make a 24-to-1
analog multiplexer from three 4061s. But if you're just using one
chip, and you don't want to turn the output off, just tie it to GND
and be done with it.

I have tied E and Vee to GND now, but it didnt help.
When I power the chip, it still sends out power to 2 of the LEDS.
I thought that 1) all outputs is off till I select one, 2) only one output in on at a time.

I can disconnect the pin3 that holds the power I want to switch and they keep lit, so its using its own power to lit these 2 leds.

Its Y2 and Y6, the second top pin on both sides.


/Jan
.

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