Microshan

Thanks for the reply, I'll try the suggested changes. Unfortunatly I only have access to my local electonics shop in the week-ends so experimenting will continue in the week-end. The good thing - it gives me some time to redo the circuit board. Regards, Mike

Thanks guys, I'll try to replace the LM358 with a OP290. They seem to be pin compatible. But I'll try a simulation first. The reason for choosing a 9V was a purely for space reasons. Might be able to lower the supply to 6V. More simulation I guess :) Mike

Hi all, I have been building a capacitive soil moisture probe using the circuit shown below. The circuit works reasonably in this 1st test version, but it uses way too much power/current in standby mode to be operated by a 9V battery. The workings of the circuit are quite straight forward. IC1A & B forms an oscillator. The output is fed to a voltage divider consisting of C3(C4) and the probe. The signal is rectified and amplified and fed to an other low frequency oscillator driving the Led. In the current configuration and used components it uses around 3mA. How can I, without doing the whole circuit over, reduce the power consumption of this circuit to be useful for battery use. Kind regards Mike