Is there an IC that I can use instead of an arduino or attiny to compare a reading from a photoresitor to a threshold value (eg 2.4v). If the reading is above 2.4v it should turn the transistor on and if it is below turn the transistor off.
Thank you for the reply. I think I will need a negative comparator. I havent thought about those questions until now. I would want it to stay on for 5 minutes after detecting darkness. It is okay if it false triggers on power up.Comparator with onboard reference -
http://www.ti.com/product/TLV3011
When photoresistor triggers comparator is there a minimum time you
want comparator to stay triggered if light level falls back below its trigger
point ?
Do you need circuit to not generate false trigger while circuit is being
powered up ?
The above would be why you might want to reconsider using ATTINY.....
Regards, Dana.
Is darkness above 2.4V or below 2.4V?I would want it to stay on for 5 minutes after detecting darkness.
What makes you think that? You can use the comparator to trigger on voltages above or below a threshold.I think I will need a negative comparator.
A comparator with a 555 timer would do it.I havent thought about those questions until now. I would want it to stay on for 5 minutes after detecting darkness.
Since the accuracy is not critical I'm pushing the limits of the cap leakage by using a 1meg resistor and a 470μF capacitor.crutschow How you going to get a 5 minute on time