# Simple battery operated Event Recorder Circuit

#### macowan

Joined Jan 3, 2019
2
I am new to this forum and really joined in the hope that I could get some advice on building a simple and compact battery operated event recorder circuit. What I want to be able to do is build a circuit that records the actual time a wire is disconnected (in real time, not via a timer). It only has to record this event once as it will be reset on a daily basis and the recording could be as simple as just showing the time the event happened in a digital display, in fact that would be preferable. I want to be able to use this to record the time of capture of animals in traps for conservation work. If anyone has any suggestions as to how this circuit might be done, or could point me in the right direction that would be greatly appreciated.

#### AnalogKid

Joined Aug 1, 2013
10,067
For compact and battery powered, nothing is going to beat a microcontroller like a PIC or AVR, one of the smaller arduinos, or something similar (there are lots to choose from). The downside is the programming.

How accurate does it have to be? What you describe is a stopwatch that displays time of day rather than seconds. Press a button (or activate some other input system) to freeze the display, press another button to bring the display back to real time.

BUT WAIT - If you don't mind having to set the clock manually after logging an event, consider a small travel alarm clock, one with a motor-driven analog display that runs on a single AA cell. Remove the battery and wire it to something that can be switched with the force of the tripwire or something like that. The activate system breaks one of the battery connections, freezing the display. $7 on ebay, zero software. https://www.ebay.com/itm/21038-Equi...FMFl:rk:5:pf:0&LH_ItemCondition=1000&LH_BIN=1 ak Thread Starter #### macowan Joined Jan 3, 2019 2 For compact and battery powered, nothing is going to beat a microcontroller like a PIC or AVR, one of the smaller arduinos, or something similar (there are lots to choose from). The downside is the programming. How accurate does it have to be? What you describe is a stopwatch that displays time of day rather than seconds. Press a button (or activate some other input system) to freeze the display, press another button to bring the display back to real time. BUT WAIT - If you don't mind having to set the clock manually after logging an event, consider a small travel alarm clock, one with a motor-driven analog display that runs on a single AA cell. Remove the battery and wire it to something that can be switched with the force of the tripwire or something like that. The activate system breaks one of the battery connections, freezing the display.$7 on ebay, zero software.

https://www.ebay.com/itm/21038-Equi...FMFl:rk:5:pf:0&LH_ItemCondition=1000&LH_BIN=1

ak
Hi ak and thanks for the response. Seconds are not important but having to manually reset would be a problem just due to the number of these that might be required-perhaps a 100 or more. Your description of "a stopwatch that displays time of day rather than seconds. Press a button (or activate some other input system) to freeze the display, press another button to bring the display back to real time." is exactly what I'm after. Any of suggestions or links to appropriate microcontroller's that might fit this?

MC

Joined Mar 10, 2018
4,057
Some thoughts -

1) GPS chip with uC could handle this. GPS would get you accurate
time of day, and they are pretty low cost now.

2) Based on your description many choices in uC. To get low power
one with LCD controller so you could use a static LCD display.

3) Low power, could have uC put GPS into sleep, then itself to sleep.
Use wire break as wakeup to uC, in turn uC powers up GPS to get the
time. Then cycle repeat, might be able to leave the last trip time
displayed on the static LCD.

4) Pick uC that has future expansion capabilities with its onboard peripheral
set. For future projects, with each project building on the prior projects ex-
perience.

My inclination would be to use a PSOC as it has a rich set of both analog and
digital peripherals, like A/D, D/A. PGA, OpAmp, Comparator, Vref. Supports
and you can actually create, either with schematic capture or Verilog, custom
components. A component is on onchip resource. Attached is a component catalog
of onchip resources, PSOC 5LP.

There is a set of videos, short, to look at what PSOC is capable of.

You can also do this in Microchip, Atmel, but they lack the breadth of analog resource,
not routable like PSOC, limited or no DSP......

There are example projects on web using PSOC with GPS, just google "PSOC GPS"

Regards, Dana.

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