Delay lamp circuit using time base circuit (1)

It is a delay lamp circuit composed of NF5 55 as the core device. VD2, vs, (1,, f., etc.) After the power supply
is turned on to form a simple diode current stabilizing circuit , (1.) both ends will output 1 L?V left {i DC voltage for the entire circuit. NF, 555 The time base circuit is connected to the monostable operating mode. Normally due to (1. Full of charge. The threshold end of NE/iS5, that is, pin 6 is at high level , the time base circuit is in reset state, and its pin 3 outputs low level , continuing E is K/operating, and the light F is not on. At this time, L FD lights up and indicates the switch position with a beam, which is convenient for finding the fire at night.     When SH is pressed, c is shorted by SB, so that the trigger end of NF5 55 is the first ②Pin is at low level, and the time base circuit is set to enter the temporary state. ③Pin outputs high level, I.ED goes out, relay K is closed, its moving contact k1 is closed, and lamp E lights up. Release SB The voltage at both ends of the Houtian capacitor cannot change suddenly. Pin ② of the Shilian circuit still remains low, and the state of pin ③ of the output terminal remains unchanged, so the light E is still on. At this time, the power supply charges to C through RI' and R. Make r. The voltage at both ends continues to increase, about t-ll(RP+R r) (1, when, c: When the voltage at both ends rises to 2/3Vnn, that is, 8v, NF.555 resets to the original stable state , ③ pin input dl is low level , relay K is released, and light E goes out. The delay time of this circuit can be continuously adjusted within the range of approximately 2drnin through the RP section.