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-- Factum Books
-- Factum Books vor 10 Minuten
Looking at the last circuit diagram (the RX). Is it correct that the TL1838 is NOT connected to ground ?? - If yes, then 'how' can it function. A TL1838 clamps it output to Gnd or through an internal resistor to Vcc, and with no Gnd then ???
Long range IR beam break detector
NuttyProf
NuttyProf vor 4 Stunden
20 Years ago while playing with flashing LEDs I got to thinking why has no LED manufacturer come up with the idea of making an IR LED with a faster and highter current oscillator built in it. That way all that was needed was an external resistor for the current limit. In theory all that is needed for the sender is an IR sender LED and the resistor to make a simple beam transmitter unit. On the receive side the detector module will have a logic out which will then go high and low acording to the presence or absence of the transmitted signal. This output of this module goes directly to a transistor for driving the relay or even if the module was fitted with a powerful output transisor could drive the relay direct. Then another step forward would be to include a lense on the LED to simplify the manufacturing of the entire tx/ rx pair. The cost, the size and simplicity of a full beam system would then go down to pennies. I dare some LED manufacturer to do this. Harry
Long range IR beam break detector
PeterN
PeterN vor 5 Stunden
BASIC-language with ANNEX32-RDS on  ESP32-Modules can play sound  via internal DAC at pin 25/26 or external I2S-IDAC. ANNEX23-BASIC language now  has a command  to speak text as MP3-files generated online/live with Google Translate API. Even MP3-Streaming of Internetradio is a matter of one command-line.. So it was easy to extend the software for the Wordclocks:  - Speak the time  via external I2S-Sound-DAC or internal DAC   in different ways  - Play some  internet radio stations .  - Speak the moduls IP-Address at startup ANNEX-BASIC-Code for talking WordClock with  ESP8266 or ESP32 : Please  see attached file
WordClocks with NeoPixel-Matrix
ElektorLabs
ElektorLabs vor 8 Stunden
Use a function generator or test CD to measure levels when changing bass and treble. There is lot of freeware that can use onboard audio or sound card of a PC for audio measurements, turn it into a generator and oscilloscope. Use 40 Hz and 20 kHz. If you use a multimeter check the level of 40 Hz, 1 kHz and 20 kHz at the output from your source (CD or DVD player, PC) to see whether they are the same, so to make sure the bandwidth of the multimeter is sufficient. Maximum change at these frequencies should be +/- 10 dB. This is approximately a change from 3 times (3.16) greater to 1/3 (0.316) of the level in mid position of the potentiometers. Look at the bass/treble graph for reference. At 1 kHz there should be almost no change in amplitude. Measuring capacitors in-circuit is difficult to interpret. Have a look at the capacitors. On them the number for the value is much like color code for resistors, so in this case ‘104’ means 10 * 10^4 * 1 pF = 100 nF.  
Preamplifier 2012 (1) - introduction and line-in/tone/volume board (110650)
Colin Gunn
Colin Gunn vor 1 Tag
Have operated the Tone defeat switch and the relays RE1 and RE2 works fine  There is a notable sound difference. 
Preamplifier 2012 (1) - introduction and line-in/tone/volume board (110650)