It lets you know the pin identification.Īnd, amazingly, it only uses a few components. It's a flyback transformer that produces a high voltage when the transistor switches off and this voltage is used to illuminate a single LED for the PNP transistor and 2 LEDs for the NPN transistor. The two LEDs in series are used to produce a voltage greater than 1.7v + 2.3v = 4v so the 4v can be used to illuminate a white LED placed on the 'Test LED' pins.
#Buku persamaan ic dan transistor switch series
The project uses a single 1.5v cell and this voltage is below the 1.7v needed to illuminate a red LED so no power switch is required. There is only one trick to get the circuit working. The phase of the transformer winding must be correct to get the circuit to oscillate. Both windings are 40 turns so it does not matter which winding is used for the primary or which is used for the feedback. The feedback winding could be a small as 10 turns but 20 turns or more is guaranteed to get the circuit to work. But if the feedback winding is not connected around the correct way, the circuit will not work. There is no danger of excess current when the feedback winding is greater than required, it just produces a very brightly illuminated LED. You can learn a lot about the effect of one winding of a transformer on another in this air-cored example by slowly bringing the two windings together to see the circuit start to work. When the flux density is very low, an air cored transformer is just as good as iron or ferrite cored and when the current is turned off very quickly in one of the coils, it produces a collapsing flux that cuts the turns of all the coils and produces a high voltage in them of the opposite polarity. This is the voltage that illuminates the LED because the supply is only 1.5v and it is not capable of doing this. Thus we can prove it is the transformer that increases the voltage. In fact the voltage is high enough to illuminates two LEDs in series. #Buku persamaan ic dan transistor switch download.
#Buku persamaan ic dan transistor switch series.
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