I'm working on a simple 555 circuit that needs to be able to run on a range of input voltages, ideally anywhere from 3-12VDC. My plan is to run the whole circuit on 3V and regulate the incoming voltage down to 3V. Even LDO regulators seem to require more dropout voltage than I'd like when starting with such low voltages, so I was thinking zener diode.
My entire knowledge of zener regulators so far is from this website (article here) and I get the basic idea, but I'm not sure how to calculate the zener regulator's resistor (R3) value when the load resistance is unknown. Can I estimate the current draw of the post-regulator circuit (fairly easy to add up 555 current, LED current, relay coil current, etc.) and calculate what resistance at 3V would draw that amount of current, and then treat the circuit as a dummy resistance for the sake of calculating my zener regulator's resistor value?
I know on the one hand that higher value resistors will waste less energy, but also that they can potentially choke off power to my circuit when running on only 3V in. Maybe after doing all the math on this I'll realize that I can't really outperform the LDO regulators anyway, but I thought it was worth checking out.
Thanks in advance for any insights!
Here's a rough version of what I'm working on:
My entire knowledge of zener regulators so far is from this website (article here) and I get the basic idea, but I'm not sure how to calculate the zener regulator's resistor (R3) value when the load resistance is unknown. Can I estimate the current draw of the post-regulator circuit (fairly easy to add up 555 current, LED current, relay coil current, etc.) and calculate what resistance at 3V would draw that amount of current, and then treat the circuit as a dummy resistance for the sake of calculating my zener regulator's resistor value?
I know on the one hand that higher value resistors will waste less energy, but also that they can potentially choke off power to my circuit when running on only 3V in. Maybe after doing all the math on this I'll realize that I can't really outperform the LDO regulators anyway, but I thought it was worth checking out.
Thanks in advance for any insights!
Here's a rough version of what I'm working on: