# 4 LEDs combination controlling

#### karmaker

Joined Apr 28, 2015
4
I need some clue where should i start.

Here is the situation:

I have four LEDs connected to a battery with resister allowing them to lit dimly.

Now, I want to add four switches. These are one way switch and can only be turned on one at a time. Function of the switches will be.

Switch 1 on: LED 1 & 2 get bright (3 & 4 stay dimly lit)
Switch 2 on: LED 2 & 3 get bright (1 & 4 stay dimly lit)
Switch 3 on: LED 3 & 4 get bright (1 & 2 stay dimly lit)
Switch 4 on: LED 4 & 1 get bright (2 & 3 stay dimly lit)

I tried the attached circuit, but, it doesn't work.

#### Attachments

• 21.5 KB Views: 55

#### #12

Joined Nov 30, 2010
18,210
That drawing is just about impossible to read, and I'm good at it!

#### karmaker

Joined Apr 28, 2015
4
I know. I was adding wires as i saw fit and this is the output. Can you suggest an IC or a simple circuit that can serve my purpose. Thanks.

#### #12

Joined Nov 30, 2010
18,210
Yeah, a bunch of steering diodes.
You only have 3.6 volts in the first place, so you should be using red LEDs. Use diodes to allow enhanced current through your chosen pairs of LEDs. The "dim" resistor arrives at a node just before the LED (which is connected to ground). The "bright" resistors connect through a diode to the same node. Finding switches that shut each other off (when pressed) are about impossible to find, but a rotary switch will do the job.

#### Bernard

Joined Aug 7, 2008
5,612
As #12 suggested, selected a bright red LED, 2V @ 20 mA. With no SW pressed, all LED's dim, 2.8 mA; SW 1 on & LED 1 & 2 bright @ 14.3 mA; SW2= LED 2&3 bright; SW3= LED 2&4 bright; & SW4= LED 1&4 bright.

#### karmaker

Joined Apr 28, 2015
4
As #12 suggested, selected a bright red LED, 2V @ 20 mA. With no SW pressed, all LED's dim, 2.8 mA; SW 1 on & LED 1 & 2 bright @ 14.3 mA; SW2= LED 2&3 bright; SW3= LED 2&4 bright; & SW4= LED 1&4 bright.View attachment 84875

It works! Thank you. My students will really appreciate your help.

This is basically a flight simulator for kids to make them understand how quadcopters work. A joystick is used for the switches.

Here I am sharing my final diagram.

#### Attachments

• 292.1 KB Views: 25
• 317 KB Views: 27

#### Bernard

Joined Aug 7, 2008
5,612
Thanks for the reply; it appreciated when a final report is given, successfull or not.

Last edited: