Author Topic: Arduino Analog Instruments  (Read 491 times)

Hidden and 10 Guests are viewing this topic.

Online Hidden

  • Global Moderator
  • Hero member
  • ****
  • Posts: 3154
Arduino Analog Instruments
« on: June 30, 2018, 04:20:18 am »
I need your help to develop some better arduino sketchs for high sampling rate for measuring the signals we need

i´m not a programer and i dont know yet how to work with the registers of arduino

i found a great source that explain how to build a oscilloscope with an arduino uno that may be a source of inspiration

www.instructables.com/id/Girino-Fast-Arduino-Oscilloscope

We need to develop the following

Pulse frequency meter

Gate frequency meter

Pulse time and width meter

Gate time and width meter

Voltage input meter (simplest one assuming it were flat dc but more complicated in case is not filtered)

Current input meter

watts input meter

electron extraction amp meter

and some thermometers around to monitor the parts!

with my system of labview i already have all this but the current is not peak... i only have average because the module for isolated low voltage readings works only on average

but i would like to have some more channels oscilloscope to be able to see all that in real time right now is likely impossible so i will have to work with what i have and think that stan didnt have all this stuff we have today... but likely had the knowledge of using simple needle amp meters and voltmeters =D

Anyone ?

Online Hidden

  • Global Moderator
  • Hero member
  • ****
  • Posts: 3154
Re: Arduino Analog Instruments
« Reply #1 on: July 28, 2018, 18:33:45 pm »

Online Hidden

  • Member
  • **
  • Posts: 176
Re: Arduino Analog Instruments
« Reply #2 on: July 28, 2018, 18:39:31 pm »
Hello fabio.

Nice project to start with.
I already built the Girino oscilloscope.
There are some changes in the code you can do, they are on the comment section of this instructable, but unfortunately if you want it to work like an oscilloscope, it is not well suitable for frequencies higher than 20khz due to the speed of CPU and the operation time need by the instructions needed to aquire the signal data.

Online Hidden

  • Member
  • **
  • Posts: 176
Re: Arduino Analog Instruments
« Reply #3 on: July 28, 2018, 18:42:51 pm »
And by the way, if you want to add more channels you can opt to buy a cheaper 2nd hand scope and connect the external trigger to the other oscilloscope that you aready have.


Online Hidden

  • Global Moderator
  • Hero member
  • ****
  • Posts: 3154
Re: Arduino Analog Instruments
« Reply #4 on: July 29, 2018, 03:25:25 am »
I see there is this big limitation in sample rate

my intention is to simply get the peak amp reading and is possible to have a 2 seconds for the sampling time to get the highest peak for example and display... this way i assume is possible to have a better resolution..

does any diference using this method?
 

Online Hidden

  • Global Moderator
  • Hero member
  • ****
  • Posts: 3154
Re: Arduino Analog Instruments
« Reply #5 on: July 30, 2018, 20:17:38 pm »
the cdaq from labview also have this sample rate limitation...

for example for the frequency meters i had to use the frequency dividers to be able to get a lower frequency for it to be able to measure...

i guess the amps present correctly because there i use the modules that come with it and as it is rms it may only drop the rms value

i want a peak ampere meter such i can know exactly what the peak was... this way i will be able to know many of the parameters in the circuit like the peak voltages and the current peak at the secondary can be directly calculated..

i have a multimeter that can take max and min values but it only measure 10 amps... so i guess the best way is to get this 30 amp module from arduino to do the job

it gives 66mv per amp and at 0 amps it gives a 2.5v output so it goes down to 0.5 volts with negative 30 amps and 4.5v with same current in the other direction... works like a resistor but has this 2.5v bias and has the feature of being isolated!

i can connect it to the oscilloscope however the values will need to be calculated manually because of the bias and this 66mv per amps division...

there is one module that is 20 amps and the mv/amp division is a round number 100mv/amp.. this should be easier to use with my oscilloscope... but it will still have the 2.5v bias to get around..

so my friend X-Blade let me try to put the question in a different manner

do you think that using the registers instead of arduino ide is better to achieve this speed? was it required for your girino oscope?






Online Hidden

  • Global Moderator
  • Hero member
  • ****
  • Posts: 3154
Re: Arduino Analog Instruments
« Reply #6 on: August 02, 2018, 01:25:32 am »
i think i found out how to get the peak amps measuring

i will have to use a low foward voltage diode followed by a capacitor at the output of the current sensor than a switch to zero it every certain number of readings...

remembering zero is 2,5 v

i also thought of something simple for using it with the oscilloscope.. i will simply use two voltage dividers

one to create a 2,5v reference point... maybe 2x 470 resistors in series so at the center i will have exactly 2,5volts to use as reference for the reading on the oscilloscope.. and i will do another divider to get intead of 66mv per amp get 50mv per amp.. for that i will probably use a higher resistor value because i dont want this load to change the reading..... probably something like a 20kohm 20turns trim pot

this way it will be able to get the capacitor charged to the highest peak it measures and the arduino will be able to catch the reading! also will be able to get the real time signal on the oscilloscope..

i think in this manner is possible to use the arduino also as the frequency meter and do at least some of all the other functions i was doing on the labview ...


 
« Last Edit: August 02, 2018, 01:43:51 am by sebosfato »

Online Hidden

  • Global Moderator
  • Hero member
  • ****
  • Posts: 3154