I have started designing a basic cue light system for theater or TV use.
Basically what I want it to do is have 1 master station and 4 outstations. When a red button is pressed on the master station, the outstation lights up with the same colour. Then when I press the green button, the red light turns off, and a green one turns on. So far I have a working prototype with 2 buttons and 2 LED's, but when the green button is pressed I have no way of turning off the red LED.
The main issue is finding a way to stop the red LED from receiving power when the green button is pressed.
Both buttons are latching, and have their own 12v LED that is switched with them, both LED's are 12v also and connected in series via an audio/DMX cable(3pin) with pin 1 as green+, 2 as red+ and 3 as neutral.
Any help would be greatly appreciated!
Thank you

 

Both buttons are latching,

If the buttons are latching, that is the problem - the green button can't force the red button to release. One way to fix this is to use two buttons that are mechanically linked together (called a bail), so when you press one it releases the other.

To do this electrically, you could use a simple SPDT toggle or rocker switch with a center-off position. One side powers red, the other side powers green.

To do this electronically, change both buttons to momentary pushbuttons that toggle a flipflop that drives the LEDs. The flipflop can be relays, transistors, logic gates, or a flipflop IC; whatever your are comfortable with.

Is it important to keep the buttons you have now?

ak

 

If the buttons are latching, that is the problem - the green button can't force the red button to release. One way to fix this is to use two buttons that are mechanically linked together (called a bail), so when you press one it releases the other.

To do this electrically, you could use a simple SPDT toggle or rocker switch with a center-off position. One side powers red, the other side powers green.

To do this electronically, change both buttons to momentary pushbuttons that toggle a flipflop that drives the LEDs. The flipflop can be relays, transistors, logic gates, or a flipflop IC; whatever your are comfortable with.

Is it important to keep the buttons you have now?

ak

It's not important to keep the switches, but I would like some indication (preferably on the button) of whether the signal is on or off. I will have a look online for switches with a built in light. Thank you very much!

 

A toggle or rocker switch with a separate light for each side will be hard to find. Can you add lights to the panel, one on each side of a switch?

Lighted momentary pushbutton switches are plentiful, but then you need something to electrically or electronically latch.

Where are you located?

ak

 

A toggle or rocker switch with a separate light for each side will be hard to find. Can you add lights to the panel, one on each side of a switch?

Lighted momentary pushbutton switches are plentiful, but then you need something to electrically or electronically latch.

Where are you located?

ak

In the UK, I'm looking at using a flip-flop circuit to toggle the lights and 'latch' the momentary buttons (keep the lights on) which would be through one of the connections on the switch (normally there is one which turns on the internal light regardless of switch position). I did think of adding extra lights, but I only have a small projects box to use, so that might not be viable. Playing around with different ways to latch now, what's your preference?

 

How about two push-buttons controlling two relays?
One button would latch its associated relay while releasing the other.
It would use two DPDT relays and two SPST push-buttons as show below.
S1 and S2 represent the two PB switches.

 

How about two push-buttons controlling two relays?
One button would latch its associated relay while releasing the other.
It would use two DPDT relays and two SPST push-buttons as show below.
S1 and S2 represent the two PB switches.

View attachment 134520

Looks good, but a little bit complicated as I'm not familiar with relay circuits! I've come up with a design that uses NOR gates to latch everything, and have added a reset switch for the latches.
When red is pressed, red lights up. When green is pressed, green lights up and red goes off. From there, red can't be pressed again until the system is reset, which turns either light off. I will try to send a picture of it in a bit!
Thank you

 

Is green ever pressed first?

If no, should it be locked out/ignored until red is pressed?

If yes, this can be done with a dual D flipflop, like a CD4013.

1 - CD4013
3 - pull down resistors
3 - switches
2 - 2N7000 transistors to drive the LEDs
1 - 0.1 uF decoupling capacitor
1 - 0.1 uF power-on-reset capacitor

ak

 

Is green ever pressed first?

If no, should it be locked out/ignored until red is pressed?

ak

It could be, say if someone was a bit dozy and unprepared, but it should allow green to be pressed straight away, which then locks out red (i.e pressing red isn't a prerequisite for green to be pressed)

 

From there, red can't be pressed again until the system is reset,

That's a requirement I wasn't aware of, and the relay circuit I show allows either button to be pressed in any order.

How is the system reset?

 

That's a requirement I wasn't aware of, and the relay circuit I show allows either button to be pressed in any order.

How is the system reset?

There is a button that resets all of the circuits (as there is one for each outstation) regardless of which light is on for any of the circuits

 

Well, if you have a circuit that does what you want, that's great.

 

Well, if you have a circuit that does what you want, that's great.

Almost, I just need to get a nor gate in a circuit. Can do one digitally but this is all analogue.

 

but this is all analogue.

???????????????????

 

As in it runs on 12v rather than 5v, with physical switches rather than microcontrollers

 

First pass at post #8. This assumes that the total LED current for each color is below 100 mA and current limiting is external.

The power-on reset (POR) uses the clock inputs. This was necessary to get the interaction that lets the green output inhibit the red input without an additional logic gate and its package. The consequence is that the POR now is edge triggered rather than level dependent.

To get a power-on reset that is delayed slightly from power-on without adding more logic gates, the reset button doesn't actually reset anything until it is *released*. It will work even if the button tap is only 1 ms, but if you hold it down expecting the LEDs to go dark, they won't until the button is released.

ak

 

There is a button that resets all of the circuits (as there is one for each outstation) regardless of which light is on for any of the circuits

Yet more late information. Maybe a wiring diagram is in order.

ak

 

Yet more late information. Maybe a wiring diagram is in order.

ak

Probably, will try to put one together tomorrow as only on my phone at the moment. Thank you all for your help!

 

Yet more late information. Maybe a wiring diagram is in order.

ak

Here is my first attempt at a circuit. I realise it's all digital on here, but don't know enough to turn it into a real design (with 12v power etc) so for now this is just a proof of concept. Any improvements to the design would be greatly appreciated!

 

Use AK's circuit in post #16.
It only uses one IC chip, while your circuit requires at least two.
That chip can be powered directly by the +12V.