Enhanced drive speeds for SW EQ mounts.

[raymo]

I saw what looked to be the usual dual axis drive kit, but with a different hand controller, that had a max speed of 16x instead of the usual 8x. This got me wondering whether there is any D.I.Y. way of increasing motor speeds on an existing hand controller, or failing that, whether one can get a different hand controller which has higher speeds available.
raymo

[billdan (Bill)]

Hi Raymo,

Electronically speaking you could change the the step size of the stepper motors - from e.g. half-steps to full steps.

The problem is re-writing the software/firmware in the hand controller and without access to the source code it would be near impossible to modify it.

Regards
Bill

[raymo]

I didn't realise that the hand controller had any software/firmware;as far as I know it just has an on/off switch for tracking, and a three position switch for 2x, 4x, and 8x sidereal rate. As one can hear the motor stepping faster with each increase in selected speed, I was wondering why the limit should have to be 8x; why not 16x or 32x or more?
raymo

[billdan (Bill)]

Sorry Raymo, I thought you were talking about the Synscan hand controller like what comes with an EQ6. That has a microprocessor inside with firmware that holds the star database and can save PEC etc.

The hand controller that you have I don't know, again you would have to open it up and have look. But from what you describe it seems there only switches in there.

Maybe somebody else who has pulled these apart may know your answer.

Cheers
Bill

[luka]

The dual-axis controller on my EQ5 (looks like this) has a microcontroller (with firmware). It reads the button inputs, calculates the tracking rates from it and controls the stepper motors.

I cannot find the link but I read about someone building their own EQ5 controller using a PIC microcontroller and writing their own software. That version could run at 16x as well.

Then I started building one myself and I did some tests - it could do about 24x before motors started stalling. It turns out that the limit was imposed by the combination of a cheap stepper motor and a gearbox with 100x gearing ratio which was needed to achieve the resolution.

GOTO drives use higher quality motors with microstepping to achieve the resolution instead of high gearing. If you look here and scroll down to the two images you will see the difference in gears used in HEQ5 and HEQ5 Pro (with GOTO).

Anyway, back to your original question, it would be difficult to reprogram the original controller. Building/buying one for your mount and which has programming for 16x would possibly work. It worked on my EQ5.

[raymo]

Thank you both, something to chew on.
raymo

[bojan]

Have a look at my solution to the problem I had with DUO controller (for Bresser EXOS2 or LXD75 mount).
I couldn't change the firmware (because the processor was read-protected) so in order to accomodate the required 5x faster motor speed, I introduced the PLL clock multiplier chip: (http://www.iceinspace.com.au/forum/s...ighlight=LXD75, post #11).

This clock multiplier can be controlled on the fly and has 2x output (as well as number of other rates)

[raymo]

Thank you very much Bojan, I'll look into that.
cheers raymo