Hey guys!
Intro
I'm building a small microcontrolled contraption (a custom timer) that I plan to put inside of the power outlet box.
Due to the low power requirement of my project and the small amount of space available, I cannot use a transformer.
What I did
I designed the thing on the attachment using standard component values -correct me if I'm wrong- in such way that the 2.2k resistor gets a 7v voltage difference between its terminals (just a little bit higher than the 5v I need).
The diode then cuts off the negative half of the wave and charges the capacitor that acts like a filter. The zener diode brings the voltage of the output to 4.89v, which is a little lower than expected but still not a problem.
The 1Mohm resistor discharges the capacitor in less than a minute (tau = 10s) and consumes around 5 microamps without external loads on the output.
What happens
When I simulate a 5kohm load, Vout drops to 2.44v. Geez! With a 1k resistor, the voltage drops to about 1v!
WTF
I'm fully aware that the circuit wasn't designed with any power requirements in mind except the output voltage, however I don't know the reason the circuit is not able to provide 1mA without dropping Vout to 1v.
PLZ HALP
What advice could you give? Which design considerations should I have in mind when designing such circuit?
And why the voltage drop is soooo huge?
Thank you for the attention.
Intro
I'm building a small microcontrolled contraption (a custom timer) that I plan to put inside of the power outlet box.
Due to the low power requirement of my project and the small amount of space available, I cannot use a transformer.
What I did
I designed the thing on the attachment using standard component values -correct me if I'm wrong- in such way that the 2.2k resistor gets a 7v voltage difference between its terminals (just a little bit higher than the 5v I need).
The diode then cuts off the negative half of the wave and charges the capacitor that acts like a filter. The zener diode brings the voltage of the output to 4.89v, which is a little lower than expected but still not a problem.
The 1Mohm resistor discharges the capacitor in less than a minute (tau = 10s) and consumes around 5 microamps without external loads on the output.
What happens
When I simulate a 5kohm load, Vout drops to 2.44v. Geez! With a 1k resistor, the voltage drops to about 1v!
WTF
I'm fully aware that the circuit wasn't designed with any power requirements in mind except the output voltage, however I don't know the reason the circuit is not able to provide 1mA without dropping Vout to 1v.
PLZ HALP
What advice could you give? Which design considerations should I have in mind when designing such circuit?
And why the voltage drop is soooo huge?
Thank you for the attention.