2 transistors as SPDT?

[bigjayman]

I am trying to make a simple circuit where one LED is lit until a momentary button is pushed that will turn it off and turn on a different LED. The key component is the tactile switch I'm using, it is the perfect dimensions for my purposes but it is a SPST-NO. I'd rather not use a relay or an IC since I am trying to make this project as small as possible. I'm hoping I can use 2 transistors but I'm not having much luck figuring out how to make it work. Any help?

 

[Harald Kapp]

until a momentary button is pushed that will turn it off and turn on a different LED

What exactly do you mean? is the momentary push buttton meant to toggle between the two LEDs, or do you want LED 1 to be on while the buttton is pressed, otherwise (button not pressed) LED 2 is on?
This makes a big difference.

 

[bigjayman]

The latter. LED 1 is on when button is pushed, when the button isn't being pressed LED 2 is on

 

[Harald Kapp]

Calculate resistors as required for your operating voltage and LED operating point.
Without further comment:

 

[bigjayman]

Thank you so much. Works perfectly. You are my hero.

 

[genifis]

Why not find a SPDT switch with the dimensions you need?

 

[AnalogKid]

1. This thread is over 5 years old.

2. This can be done with no transistors at all:

1 resistor to limit the current to *both* LEDs
1 small diode
1 SPST switch

ak