najprostszy test zasięgu modułów RF 433MHz XD-RF-5V + XD-FST

(the simplest range test for the cheapest - currently in 2014 - XD-RF-5V + XD-FST 433MHz RF modules)

setup:
- na Data Input transmittera podaję prostokąt o częstotliwości z zakresu 100Hz-100kHz.
- z data out receivera mierzę częstotliwośc odebranego przebiegu
antena 1/2L, dystans 20cm, transmitter zasilany 7,5V

efekty:
granica możliwości ok. 18-19k na tym dystansie (50% errorów)
17k wahania 2 ostatnich cyfr (~0,5%)
14kHz stabilnie (wahania <0,1%)

to samo na 9V
granica stabilności ok. 18kHz
stabilnie na 15kz

9V, 1,5m odległości
stabilność ok. 12kHz

5kHZ = 10m
2kHz = 15m
600-1,7kHz = 20m
<600Hz - miałem wrażenie że zasięg spadał

#############################

ok, that was technical ponglish, now more english

setup:
- square wave put on transmitter's data in pin, ranging between 100Hz and 100kHz. Vcc=7,5V
- tap a freq-meter at receiver's data output, adding distance and watching readings

effects:
some readings appear at 65kH, but noisy and quite not reliable, not mention the distance is ca 20cm
18k-19k is the critic edge (errors ca 50%)
at 17kHz last 2 digits floating (~0,5% error)
14kHz stable (errors <0,1%)

now transmitter working at 9V
critical freq ca. 18kHz
stable at 15kz

9V, 1,5m distance stable @ ~12kHz

5kHZ = 10m
2kHz = 15m
600-1,7kHz = 20m
<600Hz - range seens to shrink

Galeria zdjęć trójwymiarowych - real foto 3D. Pod okulary anaglificzne.

Galeria zdjęć real foto 3D anaglificznych

źródło: torty ze stolicy
i
ciasta z warszawy
starsze

the simplest (parallel) uC programmer

For AVR Tiny, Atmega and other microcontrollers

Various kinds!

The very simple, simplest BPW41 infrared reflective or trans photodiode interface to TTL or CMOS (uC, Arduino...) interface

Probably simplest BPW41 application.

 One day (in fact, it was a night) I needed simple and fast reflective transopto to precisely adjust a PWM RPM regulator. From scratch, like photodiode BPW41D i found. So I searched the net and found lots of schematics basen od op amps, bootstraps and so complex circuits. It seemed exaggerated to me. I measured that BPW generates 200-300mV static voltage  under IR diode light beam. Hey, it's very sufficient to open a transistor with a proper offset. So I made few tries and finally get a scheme like this. It worked!

The goal is to set the potentiometer, when dark diode, so base voltage is about 0,45V and Output voltage 4,5-5V.
Then with iluminated diode, base voltrage rises ca 100-150mV and output falls to 0,2 to 0,5V. Thats almost all I needed! Almost, beause of some noises on BPW input - I used speckled reflector which, together with fast (1-10MHz) diode, possibly made 400PMS counted as 17000 :).

(I suppose, when You use transreflective blend, it is not necessary)

So  I did a kind of filter to match the right range - just adding a cap (and resistor) to base. Worked great! With 100nF range is 0-2000rpm, with ab 33n 0-10000rpm. The 1K resistor is good idea, anyway, to protect BPW in a case of not proper mounting and/or setting 1,5M pot to 0.