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i have several ques:
during turn on time, why the switching current have to reach to the maximum before the switching voltage start to decay/decrease its voltage?
why there is a delay time during the turn on and turn off transitions?
why the delay time during turn on is always longer than that...
what is the diffference between general purpose npn transistor and power npn transistor？ is it the power npn transistor can sustain higher power or voltage flow??
thx.
i would like to increase my voltage output from my input from for example 5V to 12V.... so can i use voltage regulator 78LS12...is voltage regulator used to increase voltage output? is so, how should i connect the 78LS12??
thx
actually wat i plan to design is once there is no light the motor wouldnt run as the 555 timer do not trigger any output. therefore, no voltage produced which sufficient to rotate the motor instead of adding the manual switch there to stop it. So, my ques is : can i connect the output of the NPN...
**broken link removed**
this attached schematic is used the light sensor to control the motor....as the light intensity is high(as the value is around 100) the motor only will rotate... but i have problem is even the light intensity is low the motor is still running.... i m using 12 V relay. so...
i would like to simulate the circuit above in pspice in order to get the turn-off time... how to simulate it if the input voltage is 15V , the +12V is changed to +500V where current flowing though the inductor is 8A with base resistor 22 ohm in order to get the turn off time delay??
Ques:
i)what is the criteria needed for inductor, diode and resistor?
ii)what is the variation of input supply and threshold voltage affect the switching performance of the device
it din count 5 second although i nid 5 s for the led to light up once it detect light... i thought this software cant count the time for this... .
Light dependent resistor Engineering » LDR Engineering
the basic idea is come from this link first example which build a dark sensor with 555...
this is a light sensor circuit with 555 timer....the timer is monostable timer and once the light is detected, the timer will be triggered and led will light up...
my problem is when the light intensity is getting higher the led light on as it should be, but when decreasing it, the led wouldn't...
i would like to run my motor for certain time only once my switch is close..is it appropriate to use monostable timer to set the time period for my motor to run after my switch in on? if so, when is my next trigger? is it nid to open the switch and close it again for the next trigger?
i would like to ask in Proteus, the circuit run well but there is sometimes having small red or blue square at the component ... wat does it means actually?
oh ya....thx vry much~~!!! ya.. it works....^^
---------- Post added 21-06-11 at 01:20 ---------- Previous post was 20-06-11 at 23:39 ----------
i tried the attached circuit above to breadboard...but it seem to have short-circuited... do i need to concern on any criteria for running a DC motor...
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