Need help to record the time of day of an electrical pulse or a light pulse - Page 1
Forum section: electronics / projects

author: alaskaking
author_rank: Newbie
timestamp: August 16, 2017, 09:55:50 pm
content: I have this motion detector (Chamberlain CWA2000) set up in my mailbox so I will hear the beeps when the mailman opens the mailbox:https://www.amazon.com/gp/product/B002ISVJL6It works great but I need to figure out a way to record the time of day that the mailman opens the box. Something that would record the time of the beeps or the time of the green light turning off when motion is detected. The green light on the receiver stays on unless motion is detected. I thought I might be able to hook some sort of time recorder up to the wire that goes to the little buzzer in the receiving unit, but I have been unable to find such a device. I would love any advice on a time recording gadget that would do this, or how to build something that would record the time of day that the mail box was opened. I don't know much about circuits or electronics. Thanks from Alaska.

author: babysitter
author_rank: Frequent Contributor
timestamp: August 18, 2017, 10:18:56 pm
content: Do you mind running a computer all the time and hack some code in?You might try to find a way to acutate a little reed relay on beep/LED, maybe with a little help from a simple transistor.(google for relay driver)Then you could use serial port, even in the incarnation of a serial-to-usb-converter, hook up some of the handshake signals to your relay. This would signal the closure or opening of the relay to the pc.(google for rs-232, handshake, dcd, dtr, dsr, rts, ...)The PC could run a little program that waits for the handshake to change and display the time it happened.(even a tiny python program would be sufficient.)

author: danadak
author_rank: Super Contributor
timestamp: August 18, 2017, 10:44:51 pm
content: This coulod be easily done by a small amount of code and a ESP8266.You tube has lots of videos and project code on simple data transmission,flag, alarm. Github also large repository of projects.This would give you battery or solar operated device, wireless to yourPC or Android.Regards, Dana.

author: Ian.M
author_rank: Super Contributor
timestamp: August 18, 2017, 11:17:10 pm
content: Alternatively for anyone with negative aptitude for computer programming, use a DPDT relay, and wire the N.O. contact pair of one pole to latch it on. (across the relay driver circuit's output transistor. Use the N.C pair of the other pole to interrupt the battery circuit of an analog quartz clock to stop it when the relay is triggered.Set the clock to the correct time and it will stop when the relay operates and stay stopped as long as the relay has power. To start it again, briefly disconnect the relay coil (e.g. with a push to break SPST switch) and set the clock to the correct time again.If you need pure battery operation, you must use a latching relay as the current drain required to keep an ordinary relay latched by powering its coil via its contacts would be excessive. If its got two coils, you'll need to connect one to the relay driver and the other to a reset button (SPST N.O.). If its got a single coil, you need to reverse the polarity to reset it so will need a DPDT button switch, with the coil across the moving contacts, the N.C. fixed contacts coming from the battery supply and the relay driver collector, and the N.O. fixed contacts from ground and supply but the opposite way round.