I’ve modified a digital timer (like this for example: link) to control it with an arduino and nrf24l01. This part works, but now I’d like to power the arduino + nrf24l01 from the digital timer circuit, instead of using an external power source (USB).
My original intention was to use the low voltage circuit that powers the LCD screen and the timer, but that is running on 1,5V, so I can’t use it.
Next I tried using the 10V or so that comes from the rectifier bridge. I got this regulator to turn it into 5V. Without a load it works fine, but as soon as I attach the arduino the voltage drops significantly, leaving only about 2,5V output. I tried to add a capacitor, with ranges from 330µF to 1000µF, to no avail.
See the attached image for the inside of the timer circuit. The black box is the rectifier bridge. It reads DB107. The orange and green cables are used by the arduino to drive the relay.
Can anyone help me to run my arduino using power from the digital timer?