Buy 20 white LED rated 3V and 3mA. eBay has it sold for U$3 per 100 pieces, comes from Hong Kong. After you get them by post mail, put 20 pieces LED in series. Power it directly with 60V DC shall do.
LED circuits are very easy to design. An LED or Light Emitting Diode, is a very low current light source that is very safe and durable for use in your project.
1.The first step is to choose how many LED's you want to light and their type . With this simple circuit you will be somewhat limited by the amount of voltage that can be safely provided for your project.
2.Calculate the amount of voltage you need from your power supply.
Red or Orange 2.0 V
Yellow 2.1 V
Green 2.2 V
True Green, Blue, White 3.3 V
Blue (430 nm) 4.6 V
Say you want to have 3 Red LED's in your circuit. Only use the diode forward voltage value. So, 3 x 2.0 = 6V, needed.
3.DC voltage works easiest. AA, AAA, or 9V batteries are cheap and easy to find for a simple project. The simplest way to use AC as your source is a wall plug , the large black plugs . You will have to cut the plug off the end of the cord. Use a multimeter to determine the positive and negative lead.
AC voltage can also be designed in the circuit. AC will only drive the LED half of the time since the voltage travels in waves. A full-wave bridge rectifier can be used to fully power LED's. This is essentially what the wall wart is doing for you.
Find a power supply greater than the calculated diode forward voltage value from step 2. In our case we calculated 6 volts. A power supply value greater than 6 volts will be needed. If you are driving a large number of LED's, current may also be important.
4.Calculate the required LED resistor value.
LED's cannot be connected directly to the battery or power supply. The LED will be instantly destroyed because the current is too great. The current must be reduced. The easiest way to do this is by using a resistor. Calculate the LED resistor value with the following formula:
LED Resistor Value, R=(supply voltage - LED voltage) / LED current
If the resistor value is not available, then choose the nearest standard resistor value which is greater.
5.Wire your circuit together.
You can soldier the wires directly together, use crimp connectors, or use a small circuit board. Choose the best method based on the size of your project.
6.The final step is to mount the LED's in your project.
You can add momentary push buttons or on/off switches to your LED circuits.
You haven't told us enough to help you very much, but most LEDs require a resistor in series with them to limit the current. The typical operating current is between 10 and 20 mA.
You can use a combined seriesparallel connection.
1).Put 5 leds in series with resistor.(this is one series set)
2). Make such 4 sets and put them in parallel and give a proper voltage (say 10V) to its end.
....All 20 leds will glow...
Led? U mean light emitter diode?
first tell how many led's you want to use. what is the power supply
i want design led circuits with 20 leds
