Skywatcher focuser handset mods.

[SteveBz]

Hi Guys,

I'm in the process moding my Skywatcher focuser eventually to add an Arduino with an optocoupler connection to the handset.  But this question is about the 9v power supply, currently a 9v battery. As I hope you can see from the photos, the battery power supply is only connected when the button is pushed, in order to avoid battery drain.  I can't imagine this would be a problem with a permanent DC supply, so I propose to put a DC socket in the casing and bye-pass the switch altogether.

 
You can see the outer ring of the PCB is the neutral and on the left, the second ring in is positive and goes to the middle pin of both IN and OUT focus buttons.  The Upper pin is unconnected and the lower pin connects to positive.  I'd like to wire this bottom pin directly to the DC power supply.  Do you see any problems with this?

Secondly, voltage.  Option one is to buy a step up voltage adaptor to step up from 5v (USB) to 9v.  Option two is just leave it and let the focuser move a little slower, I guess it would still work.  What do people think?

I look forward to your views.

Regards

Steve.

[SteveBz]

Socket inserted.  Make sure there is enough space for the PCB and the nut that holds the socket in place.

    

Looks OK, I think.

Steve

[BXRO]

The basis for the speed controller is a small voltage regulator which I think needs a supply of between 5 and 30 volts DC. The pot alters the bias of the VR so that it's output is varied. The two push buttons then select and feed the correct polarity to the motor to give forward and reverse at the speed selected by the pot. Suggest you look up the data sheet for the VR, it should run of 5 volts,  might be a little slow just make sure you 5 volts PSU is up to the current drain

[SteveBz]

Actually, the advantage of connecting to the battery side of the switch would be that I could use a rechargeable battery.

[SteveBz]

1 minute ago, BXRO said:

just make sure you 5 volts PSU is up to the current drain

Yes.  I'm using a USB hub, but it has a socket for a power supply, so If I powered it, it would probably do.