What is the band switch metal pushbutton
Band switching switch: referred to as the band switch metal pushbuttons, mainly used in radios, tape recorders, televisions and various instruments, usually multi-pole switch. According to the mode of operation can be divided into: rotary, toggle and lever type, usually used more rotary switch.
Band switch metal pushbutton structure
Structural characteristics of the common band switch metal pushbuttons and multimeter shift switches are band switch metal pushbuttons, and its structure has two kinds: one is the BBM (BreakBeforeMake) contact type, which is characterized by the transposition of moving contacts first Disconnect the front contact and then connected after the contact, during which there is a contact with the front and rear are disconnected: The other is the MBB (MakeBeforeBreak) contact type, which is characterized by dynamic contact in the transposition has a front and rear contacts are in contact Then disconnect the front contact and keep contact with the rear contact. In the circuit design should be based on circuit usage and circuit security to select the appropriate band switch metal pushbuttons.
Band switch metal pushbutton principle
The principle of the power switch K2 is closed, then press the pushbutton switch K1, then, the crystal diode V1, V2 conduction, the relay pull. At the same time, the capacitor charges capacitor C. When K1 is switched off, C is discharged and discharged through R and V1V2. This keeps the transistor on and the relay remains on. After a period of discharge, C voltage between the two poles down to a certain value, not enough to maintain the transistor continues to conduct, the relay was released. The time interval from when K1 is disconnected to when the relay is released is called the delay time. It depends on the general C and C for the R and C of 100 microfarads, the adjustable resistor R can be obtained from 10 seconds to 90 seconds delay time.