12V DC, 4 LED Lighting Circuit Help

[FortisVenti]

Good Day!

I am an absolute novice when it comes to circuitry and electronics! Consequently, I do not have the technical vocabulary to facilitate your assistance; however, I'll attempt to be as descriptive and succinct regarding my needs.

The system that I want to construct is a 12V DC, 4 light (LED) signal system. The lights will be controlled via one or more wired switches from a distance of up to 75 feet. The system has both safety and regulatory implications; so, simplicity, dependability and field serviceability are important concerns. Design elegance, such as: 1) single switch design; and, 2) mini LEDs indicating which of the remote LED lights are currently illuminated, would be a plus, but not necessary in the initial evolution. The switch (lighting control) system will be mounted in a protective enclosure; however, the system in its entirety will be exposed to outdoor and marine environments.

The switch system I have in mind will offer the following Switch Positions (SP#) and resulting Lights (L#) illumination(s):

SP0 All Lights OFF
SP1 L1 and L2 ON; L3 and L4 OFF
SP2 L1, L2 and L3 ON; L4 OFF
SP3 L4 ON; L1, L2 and L3 OFF

I believe I can make this work using a single rotary switch and bridging SP1 and SP2 terminals with a diode. If I understand diodes correctly, when in SP1, current would flow to L1 and L2, but would be blocked by the diode and prevented from reaching the SP2 terminal (circuit) and illuminating L3. In SP2, the diode would allow current flow to: L1 and L2, via the SP1 terminal; and, to L3 via a dedicated circuit. In SP3 current would flow to L4 via a dedicated circuit.

I also believe that I can make this work using two toggle-like switches: S1) a 3 position (ON OFF ON); and; S2) a 2 position (OFF ON). In this instance, a diode would bridge between the two ON terminals of S1 (ON OFF ON) and control L1, L2 and L3 (as above); and, S2 (OFF ON) would be used to control L4.

As I stated above, I know nothing about circuitry design. I'm sure you guys will get a laugh at my lack of knowledge; however, I am here to learn. I apologize if this situation has already been addressed elsewhere in the forum; however, my searches for similar scenarios proved fruitless. If there is such a discussion thread, I would sincerely appreciate a link. Thank you all for your time and consideration.

[pebe]

Welcome FortisVenti,

Yes, you can easily do what you require by using a 4way rotary switch. That would need a 4core cable that would need to carry the power to the LEDs.

You haven't said what the application is, so I don't know whether the LEDs are normal ones or superbright types. Could you give a bit more detail because that may effect the design?

[FortisVenti]

Hello pebe! Thank you for the reply. I'm not sure as to whether the LEDs are superbright or normal. The lighting units are manufactured by a company in California; they are often used in the aviation and marine industries. The specs on the units are as follows:

Light Source: Single LED, 50,000 hour full-brightness life
Voltage: 8V to 24 V AC or DC
Current: 0.17 Amp @ 12VDC
Wiring: 2-conductor 20-gauge aircraft/marine grade cable
Environment: Harsh outdoor, marine: Waterproof, submersible to 20m

The application is for a long range, visual safety and ranging system. It is intended to provide visual safety, range state and targeting queues to shooters at distances approaching 3250 meters (2 miles). For a number of reasons, radio communications for this application are ill-advised.

I the foregoing information helps.

[AndrewH7]

Was making traffic lights, & found only need 4 wires, +iv -iv & 2 +or-, if diode on red LED so only works 1 way, or 1 could've more than 1 power supply?

[pebe]

Yes, you only need 4 wires. I am drawing up a circuit for you.

[FortisVenti]

Thanks to you both for your kind assistance!

[pebe]

Here is a circuit that includes LED indicators to show which light has power supplied to it.

I assume you cannot see the lights when operating the switch, so if safety is paramount then you really need to monitor the current to each light in case it fails. But that requires a more complex circuit.

[FortisVenti]

Thank you so much for the information and the excellent drawing. I sincerely appreciate your assistance.