switch that uses silicon gate CMOS technology to. – One Assembly and Test Site, One Fabrication achieve operating speeds similar to LSTTL, with the. Site. 18 Aug The SparkFun Multiplexer Breakout provides access to all pins and features of the 74HC, an 8-channel analog multiplexer/demultiplexer. 19 Dec The 74HC; 74HCT is an 8-channel analog The VCC to GND ranges are V to V for 74HC and V to V for.
If It turns out that the 74HC is not the right 74hcc4051 for this, is there another way to expand the number of inputs of the teensy? I’m going to add a link from the MIDI page, since this is a problem that’s come up a few times. For example on row here: For a more technical and correct answer, someone with more experience might have to fill me in. Is 10k a suitable potentiometer value? You can better reduce this effect by reading the values with 8 bits resolution and apply some simple recursive digital low pass filtering: Here’s some explanation about why you need the 74hhc4051, and how to calculate it.
Something to consider is the pot makes up most of the resistance 74hc40051 controls the speed. The formula to convert measurement error to required time constants is -ln errorwhere “error” is between 0 to 1. Are there any drawbacks when using the 3. Always remember datasheets look like comprehensive technical specs, but they’re 74hc451 material with a single purpose, to sell you the chip.
Potentiometers affecting each others when connected to 74HC
But for ohms, plus 5K from the pot, your time constant is 0. I was hoping that It would provide enough precision for 7-bit values at least since it’s stated as an example here: Most plastic film “poly” capacitors also work well.
Originally Posted by 74hc051. Opps, make that delay closer to 4ms.
No problem, thanks for your help. Results 1 to 25 of The output of the 74HC is fed to A0, and digital pins 2 3 4 is controlling the channels on the 74HC When I connect the pots direcly to two separate analog pins on the teensy, they seem to behave as expected.
It does, but only if the capacitor has stabilized to the right voltage before you make the measurement.
I’ve updated the page to also recommend HCT parts. That’s contrary to the normal nonHC advice, where adding capacitance tends to improve analog measurement quality. Anything less desirable is usually glossed over or just omitted.
I did find one pot to be noisy and replaced it. Last edited by loveaurell; at You might need to adjust the delay after the channel switching though and depending on how great resolution you need, you might have to implement some smart way to handle jitter in the readings.
Your code above has only 0.
But since it’s connected between vcc and ground, does it matter where in the circuit it’s positioned? Please allow a few hours, I will rewrite it correctly when I’ll be at home after work. The reason for using 774hc4051 74HC is that I’m planning to create a midi controller with around 50 pots and buttons, but I’m trying to get comfortable with the components first.
In this circuit it looks like you’re running the 74HC from 5V. The worst case resistance is half the pot value, plus whatever the 74HC happens to be.
The resistance of the switches will be higher when you have only 3. The voltage changes in an exponential decay, where the “time constant” is calculated by multiplying the capacitance times resistance. If so, you’re going to need to allow at least 3 ms from the time you change the 74HC control pins to when you call analogRead. Should it be as close to the pc power supply pin as possible?
Without the rapid signal switching of a 74HC switch, the slowness of a big capacitor is still much faster than a human can move the pot. Is the code at the top of the page work? Ah, when I wrote above, there was no picture, so I was not aware of the capacitor. Just don’t shave the delay in your code to the minimum and you should be fine.
Values over 1 nF really don’t make much difference.
74HC4051 – 8-Channel Analog Multiplexer/Demultiplexer
You are right, the maths are correct, but I didn’t consider some resolution problems, please accept my apologies, I wrote that in a hurry. Heres a picture of my breadboard. 74h4051 time now is The first question is, which Teensy are you using? TI’s datasheet says ohms worst case at room temperature, or at extreme temperature.
74HC – Arduino, NodeMCU, Digispark and ESP
They don’t say what it is at 3V, which is pretty typical of semiconductor vendors when a spec is really terrible. The biggest noise issue I had was with an XBee on the 3.
Is it possible to go lower the without using too much current?