You can just buy an LED bulb that flashes at this rate. I just ordered two of these from Amazon. https://smile.amazon.com/Gamma-Clarity-Meditation-Light-Bulb/dp/B08X4W6N5M/ref=mp_s_a_1_5?crid=1A12EJOIW3I12&keywords=40+hertz+light&qid=1675742192&sprefix=%2Caps%2C137&sr=8-5&ufe=app_do%3Aamzn1.fos.006c50ae-5d4c-4777-9bc0-4513d670b6bc