Muller Dynamo

[Cherryman]

   Question on the DC-DC converter. It basicly has to keep the operation voltage of the motor coils at set limit. I have seen many types and voltage setings available. Would it not be wise to use one that can handle say 35v input and that way have a buffer for the input side? So what if my coils put out 30v. The one I have now is 2.5 A rated and input of 12. Not sure where the cut off point for input is tho.

thay
       
edit:  OK, says it will take up to 24v input so safe there.

With so many replications, and maybe not exact replica's I like to suggest for those not having a dc/dc converter yet it might be wise to first build the main device, testdrive it a disired RPM,  measure the output voltage (under a load) and buy a suitable converter to that voltage.

Noted should be:
- Preferable for exact replication use the same one as R.
- Patience isn't a strong part of most people ;-)

[Nali2001]

Will the DC2DC converter then switch off automatically the output

Hello Stefan,
I also have the same dc to dc convertor and I did a test for you. Up to 12v input, the dc to dc convertor puts out what you put in. So if you put in 5v it puts out 5v. Only up until 12v input, it starts regulating it to a fixed 12v output. So if you put in 14v it will put out 12v. So there is no "under voltage cutoff"

[Nali2001]

Could you please post a clear shot of the wire, so get the spool open and show the wires from
a few sides ?

Many thanks.

Regards, Stefan.

Here it is:

[xenomorphlabs]

Hello Stefan,
I also have the same dc to dc convertor and I did a test for you. Up to 12v input, the dc to dc convertor puts out what you put in. So if you put in 5v it puts out 5v. Only up until 12v input, it starts regulating it to a fixed 12v output. So if you put in 14v it will put out 12v. So there is no "under voltage cutoff"

Probably it will have a minimum current switch-off. Unfortunately there is no
mention of it in the manual. I found it for Similar models to be around 100 mA.
Nice Test, also valuable to finally clear that wire diameter confusion!

[Hoppy]

Hi Tinu,
you have a valid point here,
But you and we don´t know, how the DC2DC converter behaves.

At the end it was set to 9 Volts output voltage I guess.

So what happens then, when the DC2DC converter gets less input voltage
than 9 Volts ?

I guess it will shut off and will not use any current anymore and the LED might
be still on for a few more seconds due to an internal cap maybe ?

So maybe the rotor is then freewheeling to just run down its inertial
energy and runs this down until the friction has eaten up all RPMs ?

I think, somebody who has the exact type DC2DC converter should
do a test to see, how this converter will behave if the input voltage
is lower than the set output voltage.

Many thanks.

Regards, STefan.

Hi Stefan, Tinu,

I have the exact same DC-DC converter and the LED is bright from 3-9V DC with output open circuit. Current draw open circuit is around 18mA.

Hope this helps.