Voltmetru/Ampermetru cu PIC 16F877A

[Vizitator kooroshi60]

Hello. Can you guys explain to me why the source "+ (positive)" should be connected to the "Ground" after the 0.1R resistor? take a look at the attached image please.

[adicontakt]

it is the gorund of the voltmeter ,not the ground of the power source

[GeoMar]

Hello. Can you guys explain to me why the source "+ (positive)" should be connected to the "Ground" after the 0.1R resistor? take a look at the attached image please.

Hello. Voltmeter is fed from separate power supply (transformer, bridge, stabilizing 7805 and 7905) and that can remedy, so it connects to the scheme, the plus (+) source (GND) of the voltmeter.

[Vizitator kooroshi60]

Hello. Can you guys explain to me why the source "+ (positive)" should be connected to the "Ground" after the 0.1R resistor? take a look at the attached image please.

Hello. Voltmeter is fed from separate power supply (transformer, bridge, stabilizing 7805 and 7905) and that can remedy, so it connects to the scheme, the plus (+) source (GND) of the voltmeter.

Thank you my friend. but can you tell me what happens electrically in this part of the circuit? In this wiring the positive panel output of the power supply is connected to the voltmeter ground. Seems a bit strange! How this wiring can correct the current flow?

[Liviu M]

If l'm remembering right, the input stage of the voltmeter is an inverting one. Because the PIC's ADC needs positive voltages, is easier to reverse the inputs (connect the voltmeter's gnd to the positive terminal of the power supply) than to build a (second) inverting stage.For the current is quite equal if the shunt is on positive or negative terminal.PS Sorry for my bad English.

[Myhayxx]

PS Sorry for my bad English.

Iti pare rau ca nu stii bine engleza?dar oare tipului asta care pune intrebari ii pare rau ca nu stie nici macar sa scrie "multumesc" in romana? Sunt de parere ca astfel de postari ar trebui discutate pe mesaj privat.

[Liviu M]

Moderatorii sunt singurii in masura sa decida daca discutiile in 'romgleza' isi au locul aici sau nu.Intrebarea in sine este, dupa parerea mea, foarte potrivita pentru aria publica si total nepotrivita pentru mesageria privata.PS Sunt destul de mare sa hotarasc singur daca e cazul sa-mi para rau de ceva sau nu.

[marik2500]

We are very pleased to have among us and an Italian " kooroshi60 we would be honored to vi with a an interesting project from your magazine Farelettronica. I have CARRIED OUT ONCE A SOURCE OF TENSION THIS magazine. ...................................Siamo molto lieti di avere tra di noi e un italiano " kooroshi60 saremmo onorati di vi con un progetto interessante da una rivista Farelettronica. HO EFFETTUATO UNA VOLTA UNA FONTE DI TENSIONE questa rivista.

[Vizitator kooroshi60]

If l'm remembering right, the input stage of the voltmeter is an inverting one. Because the PIC's ADC needs positive voltages, is easier to reverse the inputs (connect the voltmeter's gnd to the positive terminal of the power supply) than to build a (second) inverting stage.For the current is quite equal if the shunt is on positive or negative terminal.PS Sorry for my bad English.

Thank you so much. you are a really good teacher. Best regards

[Vizitator pietervp]

Hello,

 

 

I’m new on this forum but I’m from Belgium so I’m going to ask my questions in English because my Romanian isn’t that good . I’m hope that this is not a problem.

 

I'm trying to build a voltmeter and an ampere meter using a PIC and a LCD. I’m not an electronic genie so I’m going to have a lot of questions.

I’m I right that in the schematic there are 2 grounds, a “normal” and than the ground of the meter. See the picture, I used colors. These are different grounds so I can’t connect them.

 

And the second question, what is the use of two resistor marked in blue on the schematic

 

Thanks

 

Pietervp

 

[marik2500]

In urma postarii pe youtube a acestui V/A am primit solicitări din alte tari pentru detalii ale acestuia. Am indicat ca cel mai bine ar fi sa vina aici la noi pe forum sa discutam. Cred ca GeoMar este cel mai in masura sa-i lămurească pe noii nostri forum-isti din Europa! :101Poate in poza de jos schema se vede altfel!!!Another electrical schematic below !!!

[GeoMar]

Hello,I’m new on this forum but I’m from Belgium so I’m going to ask my questions in English because my Romanian isn’t that good ...

Hello and welcome to elforum.infoPlus 5Vcc be connected between semireglabil and strength that goes to pin 1, the picture posted is wrong.I changed and I attached a diagram.GND's (the circled colors) are connected together, see wiring.

[Liviu M]

Hello Pietervp,1. the schematic you posted shows only the measuring unit (the measured source appears just as a black box in the upper-left corner). That means in the schematic it is only one GND.2. as marik2500 & GeoMar already said, the schematic you posted is wrong, the schematic marik2500 posted looks better . In any case, the R1 resistor should connect the MCLR (reset pin, active low) with VDD , while the trimmer is just creating the reference voltage for the ADC.Regards,LiviuLE @marika2500: vezi ca si schema ta are probleme cel putin *) la backlight - ar trebui o rezistenta de limitare a curentului - sunt niste biete diode care direct la 5V si suficent curent se cam prajesc (si mai bun ar fi un semireglabil, sa reglezi intensitatea). *) Nu stiu daca mai sunt si altele, ca nu m-am uitat prea atent, asta mi-a sarit in ochi.

[Vizitator asd25_2005]

LE @marika2500: vezi ca si schema ta are probleme cel putin *) la backlight - ar trebui o rezistenta de limitare a curentului - sunt niste biete diode care direct la 5V si suficent curent se cam prajesc (si mai bun ar fi un semireglabil, sa reglezi intensitatea). *) Nu stiu daca mai sunt si altele, ca nu m-am uitat prea atent, asta mi-a sarit in ochi.

Am realizat si eu schema de pe site. Functioneaza perfect. Pt programarea PIC-ului am folosit un kit Velleman si Picpgm cu hex-ul modificat de Geomar pt Kinderu 56. Problema mea este faptul ca senzorul meu de temperatura este un DS18b20 si nu merge (am observat ca este din cauza rezolutiei pe care o foloseste senzorul). Banuiesc ca e vorba de o subrutina in C, aflata in fsierul sursa de aceea va rog daca puteti sa-mi dati un astfel de fisier (daca-l are cineva). Momentan la temperatura imi afiseaza 205 grade C. O sa iau oricum si un senzor DS18s20 sau DS1820 (e in jur de 10 lei). Subscriu la ceea ce zice Liviu referitor la rezistenta de limitare a curentului pe led-urile de backlight. Era sa le ard - am observat ca se incing prea tare si am limitat curentul cu o rez de 51 ohm. Spor la meșterit!

[kinderu56]

eu la majoritatea lcdurilol care leam vazut rezistenta de limitare este direct pe lcd si daia cred ca nu apus rezistenta de limitare