Light Automator: does the BS2 have a built it timer or should i build one?

arrozkongandulez

Hello people
im working in this system that will let me control 2 HID lights with the possibility of using it with a timer mode..

i kinda read that the BS2 module does not have a timer you can access.. is this correct?

i was thinkning then building a timer out of a IC406 chip so i could program it for different intervals (12hrs on 12 off, 18ON 6 OFF) and then activate it or bypass it from the stamp.... would this be a good way of tackling the problem?

would you recommend a better solution?

thanks in advance!

arrozkongandulez

oops i meant the IC4060 binary counter with an internal oscillator

Phil Pilgrim (PhiPi)

i kinda read that the BS2 module does not have a timer you can access.. is this correct?

Yes, that's correct.

i was thinkning then building a timer out of a IC406[0] chip so i could program it for different intervals (12hrs on 12 off, 18ON 6 OFF) and then activate it or bypass it from the stamp.... would this be a good way of tackling the problem?

Because that chip uses an RC oscillator, the timing will not be very accurate and will drift. If you need accurate diurnal timing, a much better choice would be an RTC chip like the DS1302.

-Phil

arrozkongandulez

Phil Pilgrim (PhiPi) wrote: »

Yes, that's correct.


Because that chip uses an RC oscillator, the timing will not be very accurate and will drift. If you need accurate diurnal timing, a much better choice would be an RTC chip like the DS1302.

-Phil

Thanks for the reply Phil, this chip sounds real interesting!!! but i think it might be too much?

i did read that the internal oscilator might drift over time, but what if i used an external with a Quartz crystal? would that be better or would that still drift too much?

thanks so much for the help!

Sapphire

The question you should start with is how much drift can you tolerate? Even a crystal oscillator for the DS1302 drifts, so you need to decide if the drift is acceptable first. Typically, the 32.768kHz crystals used for these chips will be accurate to about 1 minute per month, worse if the temperature is high, low or constantly changing. If that's good enough for your application, then this will work fine. If not, and you need much higher accuracy, then you will need a TCXO (Temperature-Compensated Crystal Oscillator) to stabilize the frequency to a much higher degree of accuracy. Dallas makes a TCXO for this chip, the DS32KHZ, and it is accurate to 1 minute per year over 0 to 40°C. That is probably the best you are going to get with this chip. And if even that is too much drift, a GPS receiver can be used to provide a very accurate clock.