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Simple delay timer circuit1/4/2024 ![]() The functioning of the circuit can be studied through the following points: I will leave the time calibration to the readers, which can be done through some trial and error. Fit external pins and socket to make the unit a plug-in type of device. įinally enclose the whole assembly in an ABS plastic box.To reset the long duration timer, just switch OFF the power and switch it ON again. Similarly try different timing positions to confirm a perfect working of the circuit. Switch ON the power supply and wait for 60 seconds to lapse, after which the LED should light up, the relay and the buzzer should also get activated. Or the variable resistor to the minimum position (60 min.). ĭisconnect the mains AC supply and join the power supply section to the timer circuit.Take utmost care and check the output voltage using a digital multimeter. Ĭonnect the input of the power supply section to AC mains.Keep the timer section separate and do not connect it yet to the long duration timer circuit. The testing procedure is done separately for the power supply and the timer section in the following manner (refer to the simple DC timer circuit schematics): Be EXTREMELY careful during the testing procedure of the circuit board. Since the power supply is transformer-less, there is no mains isolation. It is constructed using a high voltage PPC capacitor and a simple bridge configuration rectifier. ![]() Ī capacitive power supply has been incorporated to keep the unit neat and compact.įinish the board assembly of the long duration timer circuit by fitting the indicators and the output switching parts like the LED, relay, buzzer etc.This is easily done by just bending their leads itself to the appropriate joints and soldering them. Again interconnect them with each other and the IC pins. Next fix the passive components like the resistors, capacitors. Interconnect the pins of the two ICs as per the diagram by soldering small wire leads across their pins. Since we are using a general purpose board as the “PCB,” begin the construction by soldering the two ICs first, somewhere in the center of the board, keeping some distance between them. With the help of the given simple DC timer circuit schematics, just complete the following steps: The building procedure of this circuit is as simple as it can be. The accuracy of the timer is nearly 100%. The present circuit incorporates the same IC to generate the basic time pulses which is further converted into long durations of time periods by another CMOS IC 4040. In one of my previous articles I have already discussed regarding the role of IC 4060 in producing time delays. Starting from 60 seconds, it can provide a whopping 720 hours of maximum time delay. The circuit uses just a couple of CMOS ICs and yet is able to provide a wide range of adjustable timing. The circuit of a long duration timer described here is unique in its own way.
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