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Complete Your Profile- MerseyTrainz enrolled in Electronics Class1 year ago
- MerseyTrainz completed Electronics Class1 year ago
- MerseyTrainz completed the lesson Tools and Materials for Arduino in the class Arduino Class2 years ago
- MerseyTrainz followed raspberry-pi, electronics, usb, leds and 5 others channel 2 years ago
- MerseyTrainz completed the lesson Welcome to Arduino in the class Arduino Class2 years ago
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- MerseyTrainz commented on nqtronix's instructable Practical Guide to LEDs 3 - Switching & Dimming2 years ago
- MerseyTrainz commented on nqtronix's instructable Practical Guide to LEDs 3 - Switching & Dimming2 years agoView Instructable »
Hi nqtronix I'm having trouble solving one of the equations in 'Step 2: Switching - NPN Transistor'.Does this equation...R2 = (UIO - UBE) / IBE = (UIO - UBE) * GAIN / ILEDas it doesn't seem to be the same as...R2 = (5V - 0.7V) * 100 / 0.03A = 143.3k Ω ???With the values entered in, when I try to solve this one (below) I don't get the same answer as you. I get 14.3K and Not 143.3kR2 = 4.3V * 100 / 0.03 = 14,333.333 = 14.3kΩ (using a GAIN of 100)To get an answer of 143.3k I have to use a GAIN of 1000R2 = 4.3V * 1000 / 0.03A = 143,333 or 143.3kΩ (using a GAIN of 1000)I'm a newbie to electronics and need some help understanding. The series so far is great and I have learnt a lot. Many Thanks

Hi nqtronix Thank you very much for your quick response to my last comment. I'm having trouble solving another of the equations in 'Step 2: Switching - NPN Transistor'.Transistor power dissipation:P = PCE = VCE@ICE * ICE = VCE@30mA* 30mA = 20mV * 30mA = 0.6mWI Have broken down the equation as follows...P = PCE P = VCE@ICE * ICEP = VCE@30mA * 30mAP = 20mV * 30mA = 0.6mWFirst, what is substituted for the @ in the calculation, also How do we calculate the 20mA value or where does it come from.I'm not trying to be a pest, just trying to understand the equation.Thanking you, merseytrainz (Steve)