Some LED circuits explained examples from various projects: flashing LEDs, 220V LEDs and more.
We start by showing you the LED circuit in series with a resistor. You must make some calculations to figure out the resistor value, depending on voltage power supply, LED voltage drop and desired current.
Series LED circuit
(Source Voltage – LED Voltage Drop) / Amps = OHMs
Amps = mA/1000
Source Voltage = 9 volts
Voltage Drop = 3.1 volts typical for a blue or white LED
Desired Current = 13 milliamps
So the resistor we need is: (9 – 3.1) / ( 13 / 1000 ) = 452 ohms so we will use a 470 Ω resistor.
220 volt LED circuit
Caution: Do not try this circuit unless you have good knowledge about electronic devices. This circuit is connected to main power source (220V) and can give you a high electrical shock
We use one capacitor, a zener diode, a resistor and the LED.
The capacitors value depend on LED current. With a 100 nF capacitor, the LED current is 4 mA; at 470 nF the current is 20 mA.
Some LED flasher circuits…