QUESTIONS & ANSWERS

摘要

Q As a retired electrical contractor, I now have time to work in an area where I have very little experience. I have installed equipment with PLC (Programmable Logic Controller) controls and now have found time to experiment with them. I have installed a PLC to control my outside lighting, with motion detectors and wireless Christmas lighting controls. The PLC's have 24 volt DC inputs, but the motion detectors are 120 volt AC output, so I have experimented with the H11AA1 optoisolator for the 120 volt AC to 24 volt DC control. The circuit I sent you has worked for now, but the voltage drop through the 2N222A is about four volts. The PLC will operate between 16 and 24 volts, but why a four volt drop? Is there a better way to do this?