I have been trying to run a W1209 module with 5V instead of 12 volts. My application is heating a small component to 70 degrees of Celsius, mostly using a power bank or a mobile charger (Hence the 5V). The original w1209 runs at 12V DC. After posting my initial question about running the module at 5V here, I did some experiments and found that module runs happily at 5V, except for turning on the 12V relay. Now, I am thinking to just decrease the resistor R7 value, in the schematic to lower value, so that it can turn on 12V replay with 5V input. I am not sure of this idea, please suggest me if this is possible.
Thanks for your answers, I understood that only option is changing the realy to 5V relay. So, I am going to buy the following 5V relay. Please let me know if this one looks alright.
I ordered the 5V relay, but it hasn't come yet. In the meantime, I tried to use a N-channel MOSFET. But as it turns out my MOSFET is not turning on at 5V operating voltage as the voltage after Q1 is below 2V. I had to increase my input voltage to atleast 6.2V, so that after Q1 it will be 2.8V. Moreover, this voltage at Q1 is high when the relay was usually in open position and becomes low when the relay was closed. So, when I replaced the relay with N-channel MOSFET, MOSFET is switching on when it is supposed to switch off and vice versa. I think I should have replaced the relay with a P-channel MOSFET instead of N-channel MOSFET. I am updating here my progress, so that it might be useful for others. I will update again after trying with a 5V relay. I added my new schematic figure to elaborate on how I replaced relay with a N-Channel MOSFET. R value is 10 kilo ohms.