In this post we search for easy ways of deriving lower voltages from higher voltage sources, for example 3.3V or 5V from a 12V or a 24V source.
Usually a step down voltage from a higher voltage source is achieved by utilizing a linear IC for example a 78XX series voltage regulator IC or a buck converter.
Both the above choices could be expensive and/or complicated choices for obtaining a specific preferred voltage immediately for a specific use.
Zener diodes also turn out to be effective when considering accomplishing a lower voltage from a higher source, in spite of this you are unable to get adequate current from a zener diode voltage clamp. Such things happen mainly because zener diodes usually include a high value resistor for safeguarding itself from high currents, which limits the passage of higher current to the output to just milliamps, which mainly results in being inadequate for an connected load.
A fast and a clean way to obtain a lower voltage from a particular higher voltage source is to apply series diodes as demonstrated in the following diagram.
In the above diagram we are able to notice about 10 diodes utilized for obtaining a 3V output at the significant end, while other related values could also be observed in the type of 4.2v, 5v and 6V levels across the appropriate reducing diodes.
We see that usually a rectifier diode is epitomized to drop around 0.6V across itself, meaning any potential provided at a diode's anode will certainly produce an output at its cathode which would definitely be usually around 0.6V lower than the input at its anode.
We take the benefit of the above characteristic with the intention to accomplish the mentioned lower voltage possibilities from a given higher supply.
In the diagram 1N4007 diodes are demonstrated which would probably produce not beyond 100mA, even though 1N4007 diodes are graded to manage upto 1amp, it requires to be guaranteed that the diodes will not start warming up, elsewhere that will lead to considerably higher voltages being permitted to cross, due to the fact that since the diode warms up the rated drop across it starts receding when it comes to zero, that's why not a lot more than a 100mA max needs to be expected from the above design for avoiding over heating and permitting an optimal reply from the design.
For higher currents one could choose higher rated diodes for example 1N5408 (0.5amp max) or 6A4(2amp max) etc.
The disadvantage of the above design tends to be that it will not generate precise potential values at the output thereby is probably not suited to functions where customized voltage suggestions might be required or for functions where the load parameter could possibly be essential when it comes to its voltage specifications.
For this kind of functions the following configuration could very well turn out to be extremely suitable as well as helpful:
The diagram above demonstrates a basic emitter follower configuration utilizing a BJT along with a couple of resistors.
The concept is easy to follow, here the pot is utilized for changing the output to any preferred level starting from 3V or lower to the maximum given input level, even though the maximum offered output could be constantly lower than 0.6V compared to the used input voltage.
The benefit of including a BJT is the fact that it allows you to attain any specific preferred voltage utilizing least variety of parts, as well as that permits higher current loads to be utilized at the outputs, furthermore the input voltage does not have any limitations and might be increased according to the BJT's managing capacity and by certain less serious tweaks in the resistor values.
In the presented instance, an input of 12V to 24V may be seen, which is often customized to any specific preferred level such as to 3.3V, 6V, 9V, 12V, 15V, 18V, 20V as well as to some other intermediate value by a way of flicking the knob of the integrated potentiometer.
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