Hi Alex, Welcome to EasyEDA. **Don't forget that LEDs are polarity sensitve: connect the anodes towards the positive end of the supply and the cathodes to the negative.** **Get this wrong and your 12V supply will destroy them!** LEDs are current driven devices. Light output from LEDs is roughly proportional to the current through them. So if you want to drive them from a 12V supply, you will need to put a resistor in series with the LEDs to define the current through them. Here's how. 1. You will need to look at the datasheet for your LEDs to see what recommended current you can pass through each of the two types of LED. 2. Then look up what the typical forward voltage drop is across each of the two types of LED. Depending on the chemistry of the semiconductors used, your red LEDs may have a forward drop of from 1.8V up to about 4V at the recommended current. Your blue LEDs will have a forward drop of from 3.5V up to about 5V at the recommended current. 3. Depending on how well regulated the 12V supply is and what the forward drops of the LEDs are (and how much they vary from LED to LED and over temperature!) you may be able to string two or maybe more LEDs in series and use just one current setting resistor per string. Having more LEDs per string will reduce the power dissipation by reducing the number of strings and therefore the number of resistors that just dissipate power as heat. However, the more LEDs per string, the lower the voltage drop across the resistor and so the poorer the current control per string with supply regulation and temperature, because the dI/dV of the resistors (change in current through vs. voltage drop across) will be greater (because the resistor values will be smaller for more LEDs in a string). 4. Work out roughly how many strings of each colour you will have. 5. From this work out the total current drawn from the supply. Your supply is limited to about 2A so make sure that the total current does not exceed this. If it does then you will need to reduce the current through each string by the same factor until the total is not greater than 2A. 6. Note the current you have chosen for each colour of string as `Ired` and `Iblue` 7. Apply this total load current to your power supply (connect a bunch of resistors across it but check they can dissipate the power). 8. Measure the loaded voltage out of your supply. Note this voltage as `Vloaded`. 9. Work out the typical total voltage drop for a typical red string at `Ired1` (see 6). Note this as: >`Vredstringtyp`. 10. Calculate the resistor value, `Rred`, for a red string from: >`Rred = (Vloaded - Vredstringtyp)/Ired` 9. Work out the typical total voltage drop for a typical blue string at `Iblue` (see 6). Note this as: >`Vbluestringtyp`. 10. Calculate the resistor value, `Rblue`, for a blue string from: >`Rblue = (Vloaded - Vbluestringtyp)/Iblue` 11. You may not have enough information about your supply to find out the max and min loaded output voltages but you if you do then check: >`Ired_max` and `Iblue_max` at `Vloaded_max` and: >`Ired_min` and `Iblue_min` at `Vloaded_min` **The max values must be less than the absolute maximum rated currents for the LEDs.** If either of `Ired_max/Ired_min` or `Iblue_max/Iblue_min` is more than about 2 then you probably need to reduce the number of LEDs in each string by at least 1. 12. Wire the strings in parallel across a common `VCC` and `ground` rail. 13. Connect the on/off switch in series with the positive output terminal of the regulator and the `VCC` rail. 14. You may want to consider adding a >2A fuse in series with the switch. 14. Return the `ground` rail to the negative terminal of the supply. **Other notes.** You may want to be able to easily adjust the relative brightness of the red and blue LEDs so it may be wise not to put red and blue LEDs in the same string. The 12V supply will dissipate some power even when the lamp is switched off on the output side of the supply. For safety reasons, adding an on/off switch on the mains side of the 12V supply has not been described but remember to switch the lamp off at the mains when not in use. :)

To draw the schematic, do the PCB layout in - and then order the PCBs from - EasyEDA, please see: https://easyeda.com/Doc/Tutorial/ :)