power on 3 leds (red,blue or green) on toggle switch (3 positions: on/off/on) + relay

Felipe Salomão said:

But i have few doubts:
1 - last led (conected to relay) never power on together led from position 1 and 3 because, when switch is one of these positions, relay is energized, then last led not power on together.. Right ?
2 - all B columm wont be necessary, if i remove A2 to B2 connection and put move conetion from B1 to A1 and B3 to A3, right ? It would work same way, but less organized.. Its right ?

This type of circuit only is possible using relay when i use this kind of switch ?

Click to expand...

1 - right
2 - wrong (then A3 and A1 will connected and two led will glow in two positions you give it and and you will get it)

this circuit is also possible without relay as KerimF said.....

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without relay economical and efficient without noise.. but if the switch goes faulty the third led will glow always...

In normal case:
With a relay, the extra current (position 1 Green & 3 red) is the relay coil current
Without a relay, it is about the current of the blue LED (+38%).

Case of faulty switch:
With a relay, all LEDs are off.
Without a relay, the blue LED is always on

Notes:
(1) if the coil current is about or less than of the blue LED current, using relay is more efficient in both cases.
(2) Otherwise, the simple solution is efficient in case 1 (and it is not in case 2 since the blue LED would be always on).
(3) Here the simple solution looks practical because Vcc=12V. But if Vcc is low (5V for example), the extra current at position 1 & 3 may be 3 fold the blue LED current.


Added:
If a small P-channel MOSFET could be used to turn on and off the blue LED, there would be no need for an extra current at position 1 & 3.

KerimF said:

If a small P-channel MOSFET could be used to turn on and off the blue LED, there would be no need for an extra current at position 1 & 3.

Click to expand...

practicaly we know that led current will be smaller than that needed for a relay... And with a mosfet you cant eliminate the current .. led current is not a matter to concern here....

venkadeshm said:

1 - right
2 - wrong (then A3 and A1 will connected and two led will glow in two positions you give it and and you will get it)

this circuit is also possible without relay as KerimF said.....

- - - Updated - - -

without relay economical and efficient without noise.. but if the switch goes faulty the third led will glow always...

Click to expand...

Understood reply 2 !! You are right.. If i make this circuit without relay, it is less secure, right ? I also will use negative sinal to power on or power off some items from ground station like lcd, coolers, backlight, antenna tracking, etc
i will apply this to control remote air plane (like drone) (with live video) and nothing can fail), i have all working, but now i making ground station..

your last diagram, mix negative signal and positive signal, it cant have some trouble when i connect another kind of things like lcd (not only led) ?

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venkadeshm said:

1 - right
2 - wrong (then A3 and A1 will connected and two led will glow in two positions you give it and and you will get it)

this circuit is also possible without relay as KerimF said.....

- - - Updated - - -

without relay economical and efficient without noise.. but if the switch goes faulty the third led will glow always...

Click to expand...

Understood reply 2 !! You are right.. If i make this circuit without relay, it is less secure, right ? I also will use negative sinal to power on or power off some items from ground station like lcd, coolers, backlight, antenna tracking, etc
i will apply this to control remote air plane (like drone) (with live video) and nothing can fail), i have all working, but now i making ground station..

It wont make any problem with any other device connected with the power supply.......... You can use this method to toggle led only are you got it?

venkadeshm said:

It wont make any problem with any other device connected with the power supply.......... You can use this method to toggle led only are you got it?

Click to expand...

This negative feeds and this last led feed (mix negative and positive) can be used to connect or cut negative feed of lcd for example ? This wont damage device ? Or only can use this to led ?

this can be used for any device which haves a series resistance (1k here)..