DCDC Step down possible circuit?

[RandomElectrons]

Good day everyone! Me n friend want to try another back woods project. I want to step down solar panels and a waterfall generator to 12V. It does not need to be very efficient and can be quick and dirty. Could this work? Kind of like a hybrid between a linear supply and a buck converter. Or is this just a dead end idea....

 

[FvM]

It's near to a working buck converter, but without a free-wheeling diode (left inductor side to ground), the stored energy in the inductor will kill the FET.

 

[loveelectronics.net]

Hello there,
If DC-DC is said, I still recommend using the LM2596DC-DC step-down module, which is also very efficient and the circuit is simple. For details, please refer to:**broken link removed**

 

[Akanimo]

Hi,

Why the TVS diode? You need a rectifier switch connected to GND at the node upstream of the inductor, downstream of the FET.

 

[FvM]

Why the TVS diode?

As already mentioned, a buck rectifier diode is required to make the circuit work. A TVS diode is sometimes used with linear or switching regulators to cut transient overvoltages, e.g. during a startup. In most cases it's however questionable that they actually server a purpose. They are designed to absorb transients of maximum ms duration, but can't withstand larger DC currents.

 

[RandomElectrons]

Thanks for all the feedback. A freewheel diode was added and the TVS removed. The TVS is just me being cautious.



This is more of a conceptual post, then a defined solution. My thoughts about this circuit was to feed the LV capacitor from an HV source like a water pressure regulator does by restricting flow. Obviously not apples to apples. My thoughts were that a properly sized inductor pulsed at HF could act as a choke and feed voltage through. So a linear PS uses a variable R and is inefficient. Why not replaced it with pulsed HF and a choke?

 

[Akanimo]

View attachment 153486

View attachment 153513

Please reconcile the two schematics that you have posted in post #1 and post #6.

 

[RandomElectrons]

OK, what should I do?. These are two different projects. Is it taboo to have more then one thread active? Should one be completed first and "mark as solved," and then start up the next thread?

 

[BradtheRad]

It's suitable to stay with this thread since its title still describes the purpose of your project. And topologies being considered, in hopes to reach a successful design.

- - - Updated - - -

The waterfall generator needs ample load. Otherwise with a light load or no load, it tends to spin fast, wearing out the bearings prematurely.

If you only use a portion of its rated output power, then you ought to divert the remaining power to a load. Many systems send it to a water heater.

- - - Updated - - -

As an option, you can somehow reduce the force of water (or volume of water) so your generator creates sufficient power for your load. However you need to be at the stream at the same time you're watching the load, which may not be possible.

 

[KlausST]

Hi,

OK, what should I do?. These are two different projects. Is it taboo to have more then one thread active? Should one be completed first and "mark as solved," and then start up the next thread?

If you want to ask about a different project, then it's a good idea to open a new thread. Both threads may be "open" and at both threads there can be discussion. No need to close one thread before starting a new thread.
Use meaningful and descriptive headlines to divide both threads ... not to confuse the forum members.

Klaus

 

[RandomElectrons]

OK. thx for the posting info!
My desired inquiry for this post remains on the following circuit



Using an inductor as a throttle... If there was no inductor and just the FET, it would be more like a linear supply right? Ratio of FET R / Load R. Bad efficiency. So if adding the inductor to choke the current, could this maybe get decent efficiency?