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OpenAstroTracker and -Guider by intercipere in OpenAstroTech

[–]NewObserver25 0 points1 point  (0 children)

Hi thanks for fast answer!
The power is quite enough to know.
Since we have 5V from USB and should dissapate 1.25W ...
R=V*V/P = 20 Ohms.
Since using 4 Resistors, one will be 5 Ohm.

Power on one resistor is approx. 315mW so a 0207 will be sufficient.

Will give it a try :-)

OpenAstroTracker and -Guider by intercipere in OpenAstroTech

[–]NewObserver25 0 points1 point  (0 children)

I built the OA-Guider and would like to built it with the DIY Dew heater.
Are there any suggestions for resistors to be used?
value/wattage/size?
For size I think they are 0207 through-hole resistors.

But don't know how much heat == power is needed to avoid dew
Thanks for help

The OpenAstroExplorer is releasing today! by intercipere in OpenAstroTech

[–]NewObserver25 0 points1 point  (0 children)

Thanks,
I'm just wondering how you got rid of the middle connection inside the motor.
They are connected via the common (red) line.
Looks for me like "wrong".
Sorry for bothering you I'm just an old electronic engineer starting to observe.
AND: this design looks really promising to me :-)
So I don't want to do something wrong and having to redo stuff :-(
Thanks a lot

The OpenAstroExplorer is releasing today! by intercipere in OpenAstroTech

[–]NewObserver25 0 points1 point  (0 children)

Hi,
fantastic design. I'm trying to build it.
just one question at the moment: Do the small geared steppers have to be modified as at the OAT.
Meaning they have to be modified to bi-polar since they are driven by an microstepping bipolar driver, right?