Sure, this is easy. Just a single transistor/fet and a couple of R's can do the job. Bob Ammerman RAm Systems ----- Original Message ----- From: "John Pearson" To: Sent: Tuesday, August 19, 2003 3:21 PM Subject: [EE:] Circuit turned on/off by a RS232 line? Could a circuit being powered by a 9v battery and a 100mA voltage regulator, be turned on and off by a serial port line from a battery powered terminal that puts out +/- 5.5 volts on the serial line? I have a battery powered circuit that connects to a battery powered terminal, that is also battery powered, by a rs232 serial cable. It would be nice if the terminal could turn the circuit on and off through the serial link between the circuit and the terminal. There are a couple extra serial port lines that are active besides Tx and Rx that I could use. The circuit has a couple of pressure transducers that would also need to be shut down too, besides the mpu. Thanks John -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu