Muller Dynamo

[gyulasun]

Hi Gyula,


what do you think is the effciency of a simple transistor, zenerdiode and a resistor to make a dc to dc converter?

Hi crazycut,

Unfortunately,  it is the worst case situation here, can be anything from 10 to 90% depends on the voltage drop across the pass transistor and the load current. Just consider the voltage difference between the input and output and this defines the efficiency with the load current.

Only Switch-mode DC/DC converters can be considered for the higher load currents if you need efficient convertion.  The simple transistor, zener and resistor (i.e a linear regulator) can only be efficient, if their input-output voltage difference is only 0.5-1V DC, this means your recovered (and loaded)voltage as an input to the linear regulator is 0.5-1V higher only with respect to its needed output voltage (this output voltage then serves as the input supply voltage for your setup).  Just figure you have a linear regulator with say 5V voltage difference between its input-output and the load current is say 1 Amper, then the pass transistor dissipates 5W power on its heat sink and you have to make up for this loss in your setup.  (If you can manage the voltage difference to be only say 0.9V, then the dissipation reduces to 0.9W)

Gyula

[joefr]

Hi Gyula


Which DC-DC converter would you choose to be good for looping BEMF output to source:
http://www.ebay.com/itm/DC-DC-Converter-Regulator-Step-up-Step-down-2-1-/370538642812?pt=LH_DefaultDomain_0&hash=item5645d2fd7c#ht_1990wt_914


or this one:
http://www.ebay.com/itm/DC-Converter-Isolated-Power-Supply-In18V-75V-Out-12V-6W-/350287013003?pt=LH_DefaultDomain_0&hash=item518ebba48b#ht_953wt_1396


JoeFR

[DeepCut]

Hi Joe, DeepCut here from overunity.org.uk.

Gyula originally recommended this one to Romero :

http://www.maplin.co.uk/universal-3a-dc-power-supply-228639

Not sure how that compares to your two options.


Cheers,

DC.

[crazycut06]

Hi Gyula,

Thanks for the reply, I'd rather not use that ciruit, co'z im generating more heat and more input power, poor efficiency...

can you suggest a dc to dc converter ciruit that maybe a much better design to bulid? from where i live it's hard to find a ready made high efficiency converter...

cc

[DeepCut]

CrazyCut look at the two posts above yours, ebay is the best place for cheap dc-dc converters.