Wǒ shè le yīgè dìngshízhōng, bàn xiǎoshí hòu tíxǐng wǒ.
I set a timer to remind me in half an hour.
Tips
usage
In everyday speech, 定时器 is more common for kitchen/phone timers; 定时钟 emphasizes the clock-like dial or display, and is also used for time-bomb-style countdown devices in fiction (定时炸弹).
