Does this kind of circuit exist?

[burpee]

I was looking around the Internet trying to learn about batteries and LED flashlights and continue to discover not only do I NOT know what I am talking about, - I don't even know how to describe what I am talking about.

So I am going to describe an electronic circuit and then I want you folks to name or otherwise describe what this kind circuit is.

I want to find or otherwise build or create a circuit that will perform these two electronic functions.

The circuit should take a 9.6V DC source and deliver an output voltage that is "clipped" or disabled as the load voltage reaches 7.4V DC

And then turns back on as fast possible when the voltage load drops below 7.4V

I believe this circuit is similar to an LED "driver" circuit, but I refer to the load in terms of "voltage clipping" instead of current limiting.

The end result of such a circuit is to preserve the 9.6VDC source by not allowing the source to draw over 7.4VDC. (increase run time)

One engineer friend says what I want is "voltage shifting" DC to DC power supply. Does this circuit exist?

 

[Illum]

sounds alot like PWM...just limited to a preset voltage? :thinking:

 

[Mr Happy]

It's a voltage regulator circuit. If you search on that term you will find so many references you will be swamped.

One important characteristic of voltage regulators is what is called the dropout voltage. That is the required difference between the input voltage and the output voltage for the regulator to work. Typically this has to be at least 2 V. For lower voltage differences you need a "low dropout" regulator. These tend to be a little more complicated and to consume a little more power.

Most voltage regulators are linear, which means they draw at least as much current as they supply. If you want to conserve power you can use a buck regulator. A buck regulator acts a bit like a transformer and can draw less current than it supplies, but depending on the circuit design and efficiency it may or may not offer a big advantage.

In the normal way of things, voltage regulators are "normal" and LED current regulators are "special".