I'm not good at electronic engineering.
But i have to make led transmitter(for visible light communication).
Now, i use arduino and mosfet like this picture.
I should choose proper power supply(external power) and COB(chip on board) led.
I will buy 24v power supply(output 23v, 52.8w, 2.2A | input 86~264VAC).
Then, what should i check when choosing cob led?
And, Can you give me some proper led list for me?
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\$\begingroup\$ Spent a LOT more time talking about your use for this. Asking about the care and feeding of "visible light communication" is like asking about the care and feeding of "flora and fauna." It could be nearly anything. Spend some time and write out as much as you are willing about the application itself. \$\endgroup\$– jonkCommented Jan 24, 2017 at 23:34
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\$\begingroup\$ You should first find a suitable LED for your task, then find an appropriate power supply for that LED. \$\endgroup\$– Peter BennettCommented Jan 24, 2017 at 23:36
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\$\begingroup\$ @jonk Okay, i want to make LED transmitter which should blink led light as 3000Hz ~ 5000Hz.(while 1 second, it should repeat on and off 5000 times) \$\endgroup\$– JJseungCommented Jan 24, 2017 at 23:54
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\$\begingroup\$ @PeterBennett umm... there are some candidate LEDs which some papers used. Cree cxa 2520(datasheet : cree.com/LED-Components-and-Modules/Products/XLamp/…) or CXM-18(luminus.com/products/Luminus_XnovaCXM18-GEN1_Datasheet.pdf). How do i know what supply is proper? \$\endgroup\$– JJseungCommented Jan 25, 2017 at 0:00
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\$\begingroup\$ You will need a power supply that can provide the voltage and current that your chosen LED requires. Both LEDs you suggest require 35 volts, so the 24 volt supply you mention is not suitable. \$\endgroup\$– Peter BennettCommented Jan 25, 2017 at 0:29
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1 Answer
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simulate this circuit – Schematic created using CircuitLab
For successful visible-light communication, the data-link needs to handle/ignore the sunlight and the 120Hz of lightbulbs and the 80KHz of desk lighting. To ignore the sunlight (a DC source of overload), you need negative feedback used in a phototransistor (3 leads, including the base); wire 2 resistors in series, connected from collector to base. Use 100K ohms to start. Place 1uF cap from midpoint to Ground. This 2R/1C network allows DC nulling of the sunlight, but shuts down the feedback at higher frequencies, so your modulated energy gets preserved. Use a 1Kohm from collector to +5volts. Again, use a 3-lead phototransistor.
This makes a very sensitive "receiver" and you may not need much power from the LEDs.
answered Feb 1, 2017 at 5:13