/diy/ - Do It Yourself

Hi /diy/,
Is my design sound? I'd like to operate a beacon light with a dark activated switch.

The IC's circuit I used is taken straight from the spec sheet in common applications for lm3909 section. Im not worry about that, it worked before. I'd like y'all to check the switch line. The photo-transistor with direct sunlight will pull down the voltage coming in the base of the transistor, hence the transistor will be in OFF mode. When sunlight is blocked, the voltage is no longer blocked (current flow is reduced) or so I think... I took a snippet of the common emitter phototransistor circuit. Do I need to calculate voltage gain coming to the base or the 100kOhm is too much? The current gain is about 400-500. The LM3909 directs about 1mA so I want to use the 100kOhm as a current limiter.