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Take you to understand the delay switch

Update:19-02-2021
Summary:

Delay switch The delay switch is a kind of switch that […]

Delay switch
The delay switch is a kind of switch that uses the electronic component relay to be installed in the switch, and the delay switch circuit. Delay switches are divided into voice control delay switches, light control delay switches, touch delay switches, etc. The principle of the time-delay switch is the principle of the electromagnetic relay. The working principle of the relay is that when the relay coil is energized, the iron core in the coil generates a strong electromagnetic force, sucking the armature to drive the reed, and disconnecting contacts 1 and 2, 1, 3 is connected. When the coil is de-energized, the spring resets the reed, making contacts 1, 2 on, and 1, 3 off. As long as we connect the circuit that needs to be controlled between contacts 1 and 2 (1 and 2 are called normally closed contacts) or between contacts 1 and 3 (called normally open contacts), we can use relays to achieve certain control the goal of.
The working voltage of 4098 type relay coil has 3V, 6V, 9V, 12V and other specifications. The current passing through the coil is about 50 milliamperes when it is closed, and the current allowed to pass between the contacts can reach 1 ampere (250 volts).

working principle:
Close the power switch K2, and then press the button switch K1. At this time, the crystal diodes V1 and V2 are turned on and the relay is closed. At the same time, the power supply charges the capacitor C. When K1 is disconnected, because C has been charged, it will discharge through R and V1V2, thereby maintaining the transistor to continue to conduct, and the relay is still closed. After a period of discharging, when the voltage between the two poles of C drops to a certain value, it is not enough to maintain the transistor to continue to conduct, and the relay is released. The time interval from K1 disconnection to relay release is called delay time. It depends on the size of R and C. Generally, when C is 100 microfarads, the delay time of 10 seconds to 90 seconds can be obtained by adjusting the adjustable resistor R. If C is 1000 microfarads, the delay time can reach more than 5 minutes.
The diode connected in parallel on the relay plays a protective role to prevent damage to the transistor due to high voltage due to self-inductance when the relay is released from power failure.
Component specifications: J relay type 4098 working voltage 6V V1V2 transistor 9014 VD crystal diode 2CP10 or 1N4001 R adjustable resistor 100k C electrolytic capacitor 100u/6V K1 button switch.

Welding circuit:
1. Do pre-welding treatment and tin plating of all components.
2. Welding relay. Insert the relay into the corresponding hole on the printed board. Solder the 5 pins. Note that the welding time should be as short as possible, and the solder joints should be round and small.
3. After welding R and C, and the adjustable resistor R, insert the printed circuit board for welding. Pay attention to the position of the positive and negative pins when welding the electrolytic capacitor C.