BEMF Scavenger Cruda

[z.monkey]

Howdy Gyulasun,

Yeah, I agree this issue needs to be addressed.  It is a very specific phenomena, it can be measured, and in the right circumstances it is the right design.  Like in the instance where you want to maximize your flyback (BEMF), like high voltage transformers.  Automotive ignitions and electron guns in TVs are where this works good, with the right inductor.  But I don't think you can call it free energy.  The output impulse is still less power than the input, even though the output voltage goes way up...

I am cautious about using MOSFETs to try this because they don't turn all the way off.  In a relay you have a break before make condition on the switches that can't be duplicated with transistors.  Like in my low voltage example, if I used transistors, I probably would not get 21 volts open circuit.  It would be lower voltage, still there would be voltage gain, but not as much as using a relay.  In order to get the BEMF to flow as efficiently as it can you have to disconnect the inductor.  A transistor just can't do that.  There is always going to be a small leakage current preventing the inductor from rapidly discharging.  The Schottky Diode bridge gives the BEMF a low impedance path to follow, so it doesn't try and jump the relay switch gap.  I do think we can maximize the concept to make circuits more efficient, and to a large extent semiconductor manufacturers know this and incorporate these ideas into their designs.  Mo on that later...

So, thanks for you interest...
Lets make it mo betterz...

[z.monkey]

So, here I hooked up the scope on both sides of the inductor to give it a looksee.  Its ticking at 23.8 Hertz.  With a load I am getting 4.1 volt pulses in the inductor.  The battery voltage right now is 3.89 Volts.  Notice that there are some anomalous spikes in the waveform.  This is the relay contacts bouncing, which is actually helping the circuit produce BEMF.  I'll explain in a minute...

[z.monkey]

In this shot I am going to zoom in on one pulse to take a look at the switch bouncing.  This is the drawback to using mechanical contacts.  Any time you have mechanical contacts there will be high frequency bouncing, this is why there is a debounce circuit.  That one is big in digital stuff because sensitive logic will produce a stream of bounces with a mechanical switch.  If you are doing something like counting pulses its a big problem.  Here in this circuit is is providing lots of transient pulses which we are rectifying down to DC that we can use...

[z.monkey]

Then here in this shot I remove the load and adjust the scope for higher voltages.  We can see when the circuit is unloaded the voltages shoot up to 21 volts...