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Dr. Calculus technical calculators

Welcome to the Dr. Calculus pages.

What you are about to find here are sophisticated, on-line, real time calculators for specific jobs. They are designed in order to save you from the time consuming common calculations. Those calculators are not to solve "riddles" and impossible mathematic equations. They are simple in operation (as simple as can be) and each one does one specific task. These tasks are some calculations that an amateur (and not only) project designer will need to do as for example, you may need to solve several times the equation for the calculation of oscillation of a 555. Dr. calculus will do those calculations for you saving you precious time and keeping your results error free.

As you understand, those calculators are far from complete. I would need more than my life to script a complete list of calculators. The list is from time to time enriched with new scripts. In case you badly need a calculator, you may ask from us (with email of course) and you will have it the soonest possible.

All calculators are copyrighted. You may NOT copy the scripts without our permission. This would be against the international law for copyrights.

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Single transistor constant current LED driver biased with Zener Diode

This calculator is to support the LED driving and controlling methods. More specifically, it is used to speed up the calculations of the Single Transistor Constant Current Driver with voltage regulation

  If you are using normal diodes instead of zener, then put the total voltage drop across the diodes in place of the zener voltage. If for example each diode drops 0.7 volts and you have 2 diodes in series, then the zener voltage will be 1.4 (0.7+0.7=1,4)




Zener Voltage:

Zener Current:


VBE: Volts

LED Vf***: Volts

*** LED Vf corresponds to the LED's forward voltage for the calculated IC!!! Wrong value will lead to incorrect transistor power dissipation calculaton!

Base voltage (VB)   
Emitter voltage (VE)   
Emitter current (IE)   
Collector current (ILED=IC)***   
Maximum IC   
Base current (IB)   
RE Power Dissipation   
Transistor Power Dissipation***   
Max RB Current   
PRB RB Power Dissipation   
PZ Zener Power Dissipation   

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