1h timer circuit using LM122

(1) Introduction to the circuit principle. Figure 3-23 shows
a th timing circuit using LM122. The start,
reset and stop of the circuit are all operated by switches . In the figure
. Sl is the tang timer. After the timer is started,
pressing this switch again will not have any effect. S2 is the centrally located
“off” switch, the switching of which
enables the timer to complete. Charging cattle open circuit* power detection: Because charging is stopped midway , the charging position will return to the working state of the timer output line
even if the timer setting time is not reached . When c is discharged and the R/C terminal voltage is zero, the discharge position waits for the start signal of Sl. Even if the position is restored, the working status of the timer output line will not change. Therefore, when the timer is reset during operation, the status of the output line remains the same; at this moment. C starts charging again and changes to the starting point of the timer working time.     (2) Component parameter selection Component abuse is shown in Figure 3-23, there are no special requirements.     (3) The th timer circuit using LM 122 is shown in Figure 3-23.