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Senzatii tari, chinezesti!

October 14th, 2017 No comments

Cautand prin cutia cu piese, cu totul altceva desigur, am dat peste acest modul de sursa realizat de prientenii chinezi B3606 power supply. Pentru pretul platit de doar ~15$ (cu free shiping) “sursa” este oarecum bine realizata si functioneaza decent daca ai grija ce si cum alimentezi cu ea. Comparand valorile afisate pe display-ul sursei cu cele afisate de multimetrul UT61E pot spune ca are o precizie impresionanta pentru un produs atat de ieftin si fara pretentii.

Caracteristicile sursei buck sunt urmatoarele de la chinez citire :

Input voltage: 6V-40V
Output current: 0-6A
Output voltage: 0-36V
Conversion efficiency: up to 92%
Operating frequency: 150KHz
Short circuit protection: Constant
Operating temperature: -40 ° C to + 85 ° C
Control: Digital control + Digital display
Voltage regulator / Display resolution: 0.01V
Power display minimum resolution: 0.001W
Current regulation / Display resolution: 0.001A
Capacity display minimum resolution: 0.001AH
Output ripple: ≤50mV

User manual of B3606.pdf

De ce in titlu am spus “senzatii tari”? Pentru incarcarea acumulatorilor sursa e buna dar daca ai ceva montaj mai sensibil / pretentios e foarte riscant sa o folosesti in necunostinta de cauza.

In primul rand trebuie manevrata cu mare atentie! La apasarea mai lunga a tastei SET se poate intra in meniul de calibrare F1 (calibrare tensiune) si pe iesire sunt debitate in mod automat tensiunile de 2V / 24V limitata la 200mA, daca in momentul respectiv ai un consumator pe iesire si se alimenteaza sub 24V / << 200mA sansele sa ramai fara el sunt mari.

Daca esti atent si nu greseti la apasarea tastei SET atunci e foarte posibil ca supratensiune aparuta la cuplarea iesirii (overshot) sa-ti arda ceva piesele.

Nu ma pricep la explicatii savante dar pentru ca “o imagine face cat 1000 de cuvinte” atasez cateva capturi cu oscilograme.

Fara sarcina pe iesire: tensiunea / curentul setate la 5V / 1A – overshot 37% !

open%205V%201A.png

Fara sarcina pe iesire: tensiunea / curentul setate la 12V / 0.5A – overshot 20% !

open%2012V%20500MA.png

Bec 12V / 21W pe iesire: tensiunea / curentul setate la 12V / 2.5A – overshot 13% !!!

Aici timpul overshot-ului e destul de scurt dar si sarcina e mare consumatoare la rece.

Totusi daca alimentezi componente sensibil e foate riscant, nu ma refer la chestii profesionale ci la simple AO-uri sau integrate digitale.

21W%20-%2012V%202.5A.png

 

Mai multe informatii utile se gasesc in link-urile urmatoare:

https://www.eevblog.com/forum/reviews/b3603-dcdc-buck-converter-mini-review-and-how-the-set-key-could-be-fatal/

https://hackaday.io/project/4362-power-supply-b3603-alternative-firmware

https://github.com/UsrnameTaken/B3606

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RCL-meter (version 1.10)

January 4th, 2015 2 comments

RCL-meter is a low cost and minimal hardware solution for measuring:
– capacitances (5pF to 5uF)
– inductances (5uH to 50mH)
– resistances (5 Ohm to 50 MOhm)
using the PC soundcard.

rcl-meter

The required external hardware is just 2 resistors and 2 capacitors.

circuit-diagram

Version 1.10 includes an improved phase shift measurement, making the software less critical toward the quality of the soundcard.

How it works
The working principle is simple: an AC voltage, with a known frequency, is applied over a known resistor (R) in series with an unknown impedance (X). Based on the voltage ratio (Ux/Ur), the phase shift between Ux and Ur the unknown impedance (X) can be determined.
However, implementing this principle using a soundcard is not so easy. At high impedances (X) Ur is close to 0 while at low impedances Ux is close to 0. In both case it is difficult to get a sufficient accuracy. Mainly because of the inaccurate phase measurement.
In addition the soundcard inputs have a rather low input resistance and a significant input capacitance, appearing in parallel to X.
In fact a soundcard is not really suited to build a RCL-meter, in particular due to the low input impedance and relatively large input capacitance. In addition there is a lot of variation between soundcards in regard with the input impedance, input capacitance, line-in sensitivity and speaker out level.
But it is probably the nature of a radio amateur to try to use things for purposes they are not designed for …
These problems were solved by taking the Fourier Transforms of Ur and Ux and use these to calculate the voltage ratio and phase shift. After using some tricks and a lot of calculations it seems possible to build a relative accurate (and very cheap) RCL-meter.

System requirements
– As a lot of math is involved (3 FFT’s per measurement) at least a Pentium 200MHz with 8MB RAM (16MB or more preferred) is needed.
– Of course a soundcard that can handle 16 bit ADC / 44kHz sample rate. With older / cheaper soundcards the measurement accuracy can be limited, due to a strong internal coupling between speaker out and line in (see help file for details). In addition the soundcard MUST have a line-in input, as 2 signals must be measured at the same time the microphone input (as it is mono) cannot be used.
– At least Win98.

Download RCL-meter – v1.10 RCL meter 1_10

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nRF24L01 2.4GHz Radio Transceivers

August 5th, 2013 No comments

nRF24L01 2.4GHz Radio Transceivers

nRF24L01Corespondenţa pinilor transceiverului nRF24L01 pentru conectarea la placa Arduino:

Signal RF Module COLOR Arduino pin for RF24 Library Arduino pin for Mirf Library
GND 1 Brown GND GND
VCC 2 Red 3.3V 3.3V
CE 3 Orange 9 8
CSN 4 Yellow 10 7
SCK 5 Green 13 13
MOSI 6 Blue 11 11
MISO 7 Violet 12 12
IRQ 8 Gray 2 *

 

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