My project is to build a solar powered beacon. Basic target functionality is a beacon using a 1W LED, blinking with a 25% duty cycle, 1 sec on and 3 sec off. It should be on during night and off during day. This should be powered by 4 AA rechargeable batteries and the batteries should be charged by a solar panel during daytime. All this will be placed where I will not be able to reach it easily so it should operate autonomously without maintenance. And it needs to be low power since the charging during daytime will have to cover the operations during night time.
I have started with building the circuit on a breadboard to check if everything works. Since I only have basic circuit building skills I have searched the Internet for examples to start with and current setup is based on instructions from amandaghassaei on instructables.com (555 timer article) for the "blink" circuit and dan also on instructables.com (High Power LED Driver Circuits article) for the circuitry needed for driving the 1W LED.
Then I have added a LDR in series with a 1M resistor to draw the RESET input to GND when the sun is up during daytime. The solar pannel and the circuitry for charging the batteries is not yet included.

This works fine during nighttime and daytime. The LED blinks with the frequency I want and it is shut down nicely in dark.
But the problem is in dusk and twilight. When the light goes gradually from dark to light the resistance of the LDR will decrease which results in a decrease of the voltage over the LDR and the RESET input. When the voltage is above 0.75V the 555 operates as expected and the LED blinks. When the voltage is below 0,55V the 555 is shut down by the RESET input and the output (pin 3) is kept low which results in LED turned off.
But when the voltage is between that, (0,56-0,74V) the result is unexpected to me. The output from the 555 is then kept constantly high wish results is that the LED is turned on constantly. Apparently my simple solution with the 1M resistor in series with the LDR is not good enough. I need something that moves more quickly through the interval 0,55-0,75 V.
So my questions is, can anyone suggest an alternative solution that will bring the voltage down at the RESET input directly at a specific light level? I assume that I should keep the setup with the LDR in series with the resistor but between that and the RESET input I probably need some kind of amplifying circuitry that I am not skilled enough to figure out. And even better would be if there were some hysteresis built into this so I don't get the problem of frequent turing on and off the 555 then the light is exactly on the threshold.
Hope this questions are not to simple for your guys.
I have started with building the circuit on a breadboard to check if everything works. Since I only have basic circuit building skills I have searched the Internet for examples to start with and current setup is based on instructions from amandaghassaei on instructables.com (555 timer article) for the "blink" circuit and dan also on instructables.com (High Power LED Driver Circuits article) for the circuitry needed for driving the 1W LED.
Then I have added a LDR in series with a 1M resistor to draw the RESET input to GND when the sun is up during daytime. The solar pannel and the circuitry for charging the batteries is not yet included.

This works fine during nighttime and daytime. The LED blinks with the frequency I want and it is shut down nicely in dark.
But the problem is in dusk and twilight. When the light goes gradually from dark to light the resistance of the LDR will decrease which results in a decrease of the voltage over the LDR and the RESET input. When the voltage is above 0.75V the 555 operates as expected and the LED blinks. When the voltage is below 0,55V the 555 is shut down by the RESET input and the output (pin 3) is kept low which results in LED turned off.
But when the voltage is between that, (0,56-0,74V) the result is unexpected to me. The output from the 555 is then kept constantly high wish results is that the LED is turned on constantly. Apparently my simple solution with the 1M resistor in series with the LDR is not good enough. I need something that moves more quickly through the interval 0,55-0,75 V.
So my questions is, can anyone suggest an alternative solution that will bring the voltage down at the RESET input directly at a specific light level? I assume that I should keep the setup with the LDR in series with the resistor but between that and the RESET input I probably need some kind of amplifying circuitry that I am not skilled enough to figure out. And even better would be if there were some hysteresis built into this so I don't get the problem of frequent turing on and off the 555 then the light is exactly on the threshold.
Hope this questions are not to simple for your guys.