I just finished assembling the MK133, and everything is working perfectly. I am planning to enclose the project, and would like to add some external LEDs. I will solder the wires to the appropriate location on the board where it indicates “9V 50mA”.
Here is my question: Does each external LED need to have its own resistor? Or do the existing resistors already provide the appropriate voltage for the external LEDs? If the former, then what would be the appropriate amount of resistance to use with a standard 3mm LED?
If you don’t need the led’s that go directly on the board, you can connect your external led’s to these sites on the board with wires that can (within reason) as long as you like and you won’t need any extra resistors.
I do this to have the led’s mounted on a case, away from the board.
If you need both the local and external led’s, put a 1K resistor in series with the led and connect them to the external light connectors
Check the consumption of the horns. Most likely, they consume more than 50mA, so they are not suited.
If they consume less, add a series resistor. Sorry, no values. Please experiment. Add resistor to achieve identical current consumption.