ATtiny13 Control External power

Hello everybody. On the bellow picture you can see ATtiny13. Diodes are connected in series, and need 2 * 5V = 10V input. Sadly my microcontroller can give max 6V output from pin 4. Additionally microcontroller is programmed to change pin 4 output to HIGH / LOW per second so these diodes should blink. How can i connect my second power, so diodes can work (light) correctly? Sorry for my bad english…

If you feel lucky connect gronds of the voltage sources and connect

10V --- LEDs --- current limiting resistor --- ATTiny pin.

It should work somehow (pulling LOW = LEDs on, pulling HIGH = LEDs off). But it is not safe way to drive LEDs, using transistor is better.

Transistor was the answer. Thanks a lot!