![]() Keep in mind that two identical photoresistors may have different resistance ranges. You can check the resistance of the photoresistor in low and high light levels with an ohm meter. The typical range of a photoresistor runs from about 3K ohms in high light levels to many Mega ohms in low light levels. As the light gets dimmer, the resistance increases. In bright light, a photoresistor has a lower resistance. Photoresistors or Light Dependent Resistors (LDR) are light sensing devices. To prevent back EMF, a diode needs to be placed in parallel with the coil. This induces a large reverse current in the coil, which can damage other components in the circuit. Back EMF happens when the electromagnetic field surrounding the coil collapses back into the coil. When working with inductive loads like relays, solenoids, motors, or stepper motors, it’s important to protect your circuit against back EMF. When the switch is closed, current flows through the coil and the electromagnetic field produced from the coil causes the high voltage terminal to switch to the normally open position: With no current flowing through the coil, the relay is in the normally closed position: Inside the relay is an electromagnetic coil that actuates a high voltage switch when there is current flowing through the circuit. They can be configured to switch AC line current to loads like fans, motors, and lights. Function to disable a TIMER, ex: myTimer.Relays are often used in home automation projects. initialize lastTime to current millis() or micros() Function to enable and initialize a TIMER, ex: myTimer.EnableTimer() this TIMER did not expire or it is disabled If (EnableFlag = true & currentTime - StartTime >= Interval) is the TIMER enabled and has the TIMER expired? TimerType = use ms or us timing, MILLIS/true = millis(), MICROS/false = micros() ![]() EnableFlag = is TIMER enabled/allowed to be accessed Restart = do we restart TIMER automatically Interval = interval/delay we are looking for StartTime = the time TIMER was (re)started Delay time expired function "CheckTime()" MakeTimer(unsigned long ST, unsigned long INT, bool RES, bool ENA, bool TT) myTimer.CheckTime() and myTimer.EnableTimer() and myTimer.DisableTimer() You have the following class functions: ![]() myTimer.StartTime, myTimer.Interval, myTimer.Restart, myTimer.EnableFlag and myTimer.TimerType Each TIMER object is made up of 5 variables: 0, 200UL, true, true, MILLIS //StartTime, Interval, Restart, EnableFlag, TimerType (MILLIS/MICROS) makeTimer myTimer = //create a Timer named "myTimer" TimerType = true/MILLIS = millis(), false/MICROS = micros() EnableFlag = is "this TIMER" enabled/allowed to be accessed Restart = do we start "this TIMER" again and again Interval = Interval/delay time we are looking for StartTime = the time this "TIMER" was (re)started Note: since code takes time to execute, precise micro second timing is difficult. #define isRELEASED HIGH //INPUT_PULLUP-pin-GND #define isPUSHED LOW // ~50k normally open ![]() #define noCHANGE -1 //there was no change in switch state It does not use an RTC, it just uses the millis() technique BWD for timing. Here is a skeleton sketch I often use when a new sketch is started. Lots of volunteers will help, but you need to put effort into learning.Īn RTC (ex: DS3231) is something that is needed for accurate time of day operations. Could you please help.Ĭonst unsigned long eigth = 8UL 36001000 I had written a code but I'm unable to retrieve the required output, I figure it might be the Delay function and I should refer the Blink without Delay but I'm unable to get it. Then from 16:00:00 to 24:00:00 Rela圓 and Relay1 should be HIGH and Relay2 should be LOW and so on for about 999 Days. Then from 08:00:00 to 16:00:00 Relay2 and Rela圓 should be HIGH and Relay1 should be LOW and Now, beginning at 00:00:00 Relay1 and Relay2 should be HIGH for eight hours i.e. For clear understanding naming relays as Relay1, Relay2 and Rela圓 I have three 5v relays which I want to operate in 8 hours interval daily which means any two out of the three would be active at any point of time in a day. ![]() I very recently have started tinkering around and am unaware of most of the technicalities, ![]()
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