Dark active Switch Circuit 741 Opamp

with the LDR circuit diagram keep on working as a dimmer switch. Circuit, four resistors, a opamp, two potentiometers, an LDR, a switching transistor and consists of a lamp. Circuit, the value of resistor R1 ARD is directly proportional to the internal resistance of the 6-12V works as a voltage divider.

Ldr1 depending on the internal resistance , potentiometer RV1 ldr1 fall on the task according to the degree of accuracy for the amount of light is used. RV1 is subject to a voltage divider . Therefore, the resistor LDR1 and R1 divided by the value of the material , divided by the resistance value RV1 is constantly compared by U1 . Here RV1 potentiometer 6V and that ldr1 too dark Assuming that , ldr1 the internal resistance will be higher U1 ‘s inverting input on the voltage , 6V a value close to or a little more than take a value from the U1 (741 opamp) output will be a positive voltage .

By triggering it L1 Q1 through R3 will provide the lighting . L1 emitting light with a certain reduction in the internal resistance of ldr1 will be observed that this would attract the opamp output to 0V going to cut transistor T1 , L1 will flash. Alone to be considered is that, assuming that the resistance R4 on the opamp output from a constant voltage of transistor Q1 will be concerned to go to slaughter will be hampered. R4 resistance, voltage of transistor Q1 chassis will draw on the oval . RV2 potentiometer 741 OpAmp will change the gain will react against . If the resistance of the potentiometer RV2 is large , the opamp as a comparator to operate , will operate as an amplifier is small while .

741 Op Amp Pinout