Multiple Voltages 3.3V, 5V from 12V without ICs or inductors

In this post we try to look for effortless techniques of deriving lower voltages from higher voltage sources, for instance 3.3V or 5V from a 12V or a 24V source.
Generally a step down voltage from a higher voltage source is acquired by making use of a linear IC for instance a 78XX series voltage regulator IC or a buck converter.
Both the above alternatives is generally very expensive and/or difficult alternatives for acquiring a selected needed voltage instantly for a certain utilization.
Zener diodes also emerge as valuable with regards to obtaining a lower voltage from a higher source, having said that it is never possible to get plenty of current from a zener diode voltage clamp. This occurs due to the fact zener diodes generally consist of a high value resistor for preserving itself from high currents, which blocks the passage of higher current to the output to just milliamps, which generally ends up being not having enough for an related load.
An easy and a clean way to gain a lower voltage from a certain higher voltage source is by utilizing series diodes as presented in the following diagram.
In the above diagram you can easliy observe about 10 diodes used for developing a 3V output at the extraordinary end, while other similar values can certainly be found in the kind of 4.2v, 5v and 6V levels across the suitable decreasing diodes.
We identify that generally a rectifier diode is identified to drop around 0.6V across itself, meaning any potential given at a diode’s anode would probably develop an output at its cathode that would be generally somewhere around 0.6V much less than the input at its anode.
We take the interest in the above aspect with a view to obtain the suggested lower voltage chances from a given higher supply.
In the diagram 1N4007 diodes are presented which would definitely generate not above 100mA, despite the fact that 1N4007 diodes are ranked to take care of upto 1amp, it must be made sure that the diodes never commence warming up, in any other case that might contribute to considerably more voltages being able to deliver, simply because while the diode energizes the rated drop across it commences receding in the direction of zero, that’s why not above a 100mA max really should be expected from the above design for stopping over heating and allowing an optimal result from the design.
For higher currents one might select higher rated diodes for instance 1N5408 (0.5amp max) or 6A4(2amp max) etc.
The weakness of the above design is usually that it will probably not deliver exact potential values at the output as well as is certainly not appropriate for uses where customized voltage recommendations could be desired or for purposes where the load parameter might be fundamental with regards to its voltage features.
For such type of programs the following configuration could possibly develop into quite appealing and even valuable:
The diagram above displays an easy emitter follower configuration making use of a BJT in addition to a handful of resistors.
The plan is easy to understand, here the pot is needed for modifying the output to any required level beginning with 3V or lower to the maximum provided input level, despite the fact that the maximum accessible output will be usually a lot less than 0.6V when compared with the utilized input voltage.
The main advantage of utilizing a BJT is always that it permits you to realize any kind of required voltage making use of bare minimum range of elements, in addition enables higher current loads to be considered at the outputs, additionally the input voltage lacks the constraints and could be increased in accordance with the BJT’s dealing with capacity and by a few insignificant tweaks in the resistor values.
In the provided illustration, an input of 12V to 24V can be viewed, which might be designed to any kind of required level such as to 3.3V, 6V, 9V, 12V, 15V, 18V, 20V or even to almost every other intermediate value as a result of flicking the knob of the provided potentiometer.