According to the website, you can just change a couple wires and it will work with 50 Hz power. This changes the divide-by-6 circuit to divide-by-5. <a href="http:&#x2F;&#x2F;www.transistorclock.com&#x2F;50Hzmod.pdf" rel="nofollow">http:&#x2F;&#x2F;www.transistorclock.com&#x2F;50Hzmod.pdf</a>