Construire cosfi metru

[corabi]

Buna searaAs dorii sa constuiesc un cosfi metru, care sa aiba la iesire o tensiune sau ceva pentru calcularea factorului de putere, si sa poata fi montat la nevoie si la iesirea unui transformator de curentAstept sfaturi concrete .Multumesc anticipat

[corabi]

platesc..............................

[Dr.L]

pai posteaza la servicii...

[corabi]

aici am postat pentru construire, platesc pentru sfaturi, sau orice alta contributie.nu am scris ca vreau sa cumpar unul facut.

[Dr.L]

Pai plata se face numai la bazar...

[radusa]

Pun o schema are a aparut in revista EDN in 1994.Este o varianta low-cost a unui power factor meter.Textul original:"The circuitry in Fig 1 allows the ICL7106/7107 digital-voltmeter IC, IC4, to measure power factor to 0.1% resolution and operate from a single 9Vdc supply. An important feature of the circuit is that variations in load current, line voltage, and line frequency do not affect measurements. For inductive loads, power-factor measurements are accurate to 1% in the range of 0.85 to 1. The circuit derives two dc voltages, VM and VMcos[theta], that go to the REF HI and IN HI inputs of IC4, yielding the power factor (VMcos[theta]/VM). A unity-gain follower, a precision rectifier (IC1A and IC1B), and an RC filter obtain VM by rectifying the waveform from the secondary winding of the voltage transformer, T1. A synchronous detector (IC2 and IC3) derives VMcos[theta]. The current transformer, T2, provides the waveform, v(t)=kIOsin(2[pi]ft±[theta]). Buffer IC1B squares this waveform, deriving control waveforms for the synchronous detector. The synchronous detector operates on the output of the input-voltage follower, IC1A, yielding a dc output equal to VMcos[theta]. (DI #1403) Schema originala, dar care eu o am salvata intr-un format cam mic si se citeste mai greu:Si o schema de pe net identica cu cea din EDN, cu exceptia valorilor rezistentelor din iesirile lui A2a si A2b care la EDN imi par a fi de 47k iar in schema de pe net sunt de 4.7k. Totodata condensatorii de pe REF-HI si de pe IN-HI par a fi de 3.3uF la EDN. In rest totul este identic.

[d2134]

http://blog.copcea.ro/files/tehnium/revista/9911i.pdf

 

Vezi la pagina 16. In practica poti folosi AO mai moderne.