| 摘要 |
PURPOSE:To enable selection of one-minute timer or one-hour timer with a simple construction by counting the timer time with pulses fed to a time counting circuit in a cycle corresponding to a selected set range. CONSTITUTION:When a switch S3 is connected to a contact M, FF F2 is set through a differentiation circuit A4 and inputs a high level set output P1 into a gate circuit G2 and a D terminal of FF F1. With the application of a high level set output from FF F1, the output of the circuit G2 turns to a low level causing a gate G3 to open. Consequently, one-minute pulses from a divider D is applied to a counter C for which the time of a timer is set and the down counting thereof is started, constituting a one-hour timer. On the other hand, when the switch S3 is connected to a contact S, the down counting of the counter C with one-second pulses from the divider D, constituting a one-minute timer. This enables the selection of either one-minute timer or a one-hour timer. |
