| 摘要 |
PROBLEM TO BE SOLVED: To provide a relation between brightness and turn on and off of a TRIAC with hysteresis. SOLUTION: A solar battery SB detects brightness of external light to turn on and off a switching element SW consisting of depletion mode MOSFETs Q2, Q3 due to its electromotive force. A series circuit of the switching element SW and a resistor R2 is connected between T2 terminal of a TRIAC Q1 and the gate, and the TRIAC Q1 is inserted between power supply E and a load L. A series circuit of a resistor R3 and a light emitting element LE is connected with the TRIAC Q1 in parallel. Consequently, when the surroundings are bright, the switching element SW is off and the TRIAC Q1 is off, and at this time, the light emitting element LE is lit and light from the light emitting element LE enters the solar battery SB together with external light. When the surroundings become dark, the TRIAC Q1 is turned on, and the light emitting element LE is turned off. That is, it is possible to give hysteresis due to turning on and off of the light emitting element LE. |
