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hi need help in validating my schemtics

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Mar 27, 2022
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Hi , this is my first post here , i'm so happy to find edaboard .
this is my second board and i dont have much experience so i need help validating the schematics
and adding protections to all the parts. Thank you and the board will be open source to contribute back

Screenshot (6).png

Screenshot (7).png

this is digital ouput to control 12v/24v dc voltages

Screenshot (10).png

Screenshot (9).png

Screenshot (8).png


I've seen a lot of circuits. But I don't find the idea behind your circuits.
I'm even not sure what is input and output.

A lot of questions.
Let's start with the first picture:
* DIN sounds like a digital input..but then you have two outputs.
* Why are there two resistors to 12V and 24V respectively?
* What is VIN?

Second picture:
I guess it's an open_source power output. (Low sIde power switch)
It misses Mosfet overvoltage protection (ESD, kick back voltage of inductive loads)
What does "3/1" mean?
What is the dout level? Where does it come from?
What Led current do you want?

Third picture:
It says analog output 0..10V
But how can it be 10V with only 5V supply?
Why 2 x 47R in series?
What are the trimpots for? And what value do they have?
Why R3 and R6 have different values?

I stop here..

I ask myself why you need so (complicated) non standard circuits. Do you have special requirements?
What's wrong with the standard circuits you can find million times in the internet?

Please give more informations to each circuit. Voltages, currents, requirements, frequencies, accuracy, precision, your ideas...


sorry my fault for not editing them completely before posting , the whole idea is to make this system be able to take digital inputs of either 12v or 24v and convert that to 5v or 3.3v . incase of 5v will add voltage divider at the mcu end to scale it down. please note im a novice so my answers might not be very accurate

picture 1:
a. this circuit is to take 12v or 24v from a sensor ouput pin and feed it as an input to the micro controller,so im using jumper to either select 12v or 24v and feed that to mcu.
b. to make bring the voltages down , its where the 12v and 24v are applied and not the other way around
c. VIN label is for the input from sensor , sorry will change this to input or something

picture 2:
a. it is supposed to turn on a device when there is voltage on the dout pin
b.yes will add a flyback diode would that be enough? i thought the f6 resettable fuse would be enough
c. 3/1 is to indicate that this is the first dout circuit out of 3
d. it comes from mcu the original schematics are for 5v and i want to do it for 3.3v if not possible with irfz44n are there any good easily available affordable logic level mosfets which can operate atleast 5a dc.
e. 10ma to 30ma is the led current im looking at to just light the led as a status

picture 3:
yes will correct that to analog power so it can be powered with anything below 30v dc (i.e what my reference schematics have) im following pi extends schematics just started simulating these circuits on easy eda please suggest if there are any better alternatives for this

i want my board to take digital input of 12v or 24v (if possible 5v too), analog inputs of 0 to 10v and 0 to 25ma , and be able to give analog output of 0 to 10v and 0-25ma . my mcu is 3.3v can you please provide any links or reference designs. this means a lot to me thank you


Please draw every schematic with signal flow from left to right.
You could make a combined 12V and 24V input without jumper. It's a question of threshold voltage and voltage limiting.
I recommend to use a suitable connector for the sensor. What signals does it need?
I also don't recommend to try to make an overly complex circuit. If you have an 24V system, then design it for 24V.
If you have a 3.3V MCU, then design it for 3.3V.
I also don't recommend to use a LED the way you do, because it has influence on input threshold. (Using a red LED instead of a green LED will move your threshold voltage), it also draws it's current from the input. And depending on input voltage it may be dim and you still don't know whether the MCU sees HIGH or LOW. Do you really need it? Or is it "nice to have" and could be replaced by the MCU (display, interface, ....which tells you what the MCU really sees)
* where do you want the thresholds for the inputs?
* what timing accuracy do you need and what switching frequency do you expect?

Some more information:
Where is your circuit used? Who uses it?
If it's just your hobby project, then maybe a resistor divider is suitable. Maybe add protection (zener, double diode) against overvoltage and reverse voltage.
If it's for a high reliable industrial device you need defined thresholds, defined input impedance, ESD protection, EMI / noise filter, schmitt trigger, rugged against some misuse (24V instead of 12V, wrong polarity ...)
(I use all: from 2-parts voltage divider ... up to 10 or more parts)

I guess this sounds complicated. But you should at least be more detailed with your informations:
* What exact "sensor" do you mean, and what is it used for?
* what exact MCU do you use, and at which supply voltage?
* what exact "device" (driven by your outputs) do you mean? Relay, motor (inductive), electronic device (capacitive), PWM'd? (frequency)

The problem is: We can currently not validate whether the circuit is useful or not. It may work ... or not. It may cause no problem, immediate problem, or longtime problem.

hi klaus thank you for your patience i want to make a general purpose plc style standard input and output pin mapped board, the mcu im going to use will be rp2040. the voltage systems that i want this board to be capable of are 12v and 24v. so can you guide me to any refernce designs , im following this particular schematics.


  • pixtend_v1.2_circuit_full.pdf
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