Fiddling with an autofocusser

[Gina]

Ah, I think I get the picture Take the servo, remove the electronics and you're left with a DC motor with 2 wires. This is then connected to the control circuit through a reversing switch (2P2W toggle switch). Correct?

I should say... I know nothing about these servos but no doubt you've guessed that

[Leebert]

Ah, I think I get the picture Take the servo, remove the electronics and you're left with a DC motor with 2 wires. This is then connected to the control circuit through a reversing switch (2P2W toggle switch). Correct?

I should say... I know nothing about these servos but no doubt you've guessed that

For the controller that Bizibilder has you are correct I believe.

For the servo tester in the link I posted, leave the servo as it is. It just plugs in to the tester 'as is'

[Bizibilder]

Gina is right - remove the electronics from the servo and, most importantly, remove the plastic tab that prevents the servo from rotating 360° - its moulded onto one of the gears. Then you are left with a motor and gearbox all neatly held together by the case.

I discovered a supply of small motors the other day - I took apart a computer DVD read-writer - the drawer is opened and closed by a neat little 5v dc motor which I reckon could be useful for a few things. One I dismantled was screwed in place and had two wires to it the other was soldered directly to the circuit board via two tabs - dead easy to solder a couple of wires onto. I believe these are sought after by builders of small robots? I nearly forget you get a couple or three small plastic gears as well.

[Gina]

Gina is right - remove the electronics from the servo and, most importantly, remove the plastic tab that prevents the servo from rotating 360° - its moulded onto one of the gears. Then you are left with a motor and gearbox all neatly held together by the case.

Thanks

I discovered a supply of small motors the other day - I took apart a computer DVD read-writer - the drawer is opened and closed by a neat little 5v dc motor which I reckon could be useful for a few things. One I dismantled was screwed in place and had two wires to it the other was soldered directly to the circuit board via two tabs - dead easy to solder a couple of wires onto. I believe these are sought after by builders of small robots? I nearly forget you get a couple or three small plastic gears as well.

That's a good idea - I've got several old CD and DVD drives about doing nothing, I'll strip one down. Also, several years ago I dumped an old printer that had stopped working. I was having a period of ill health and not myself I wasn't up to repairing the printer and bought a new one. I had a bit of a clear out and actually threw it out I usually keep old stuff for the parts. This time I didn't and have regretted it ever since. I even found out that the trouble may have be fixed quite easily and it had been a good printer. Since then I have upgraded printers several times and still have the old ones so I'll be stripping the oldest one of those too.

I have another use for small DC motors and gears - rotating CCTV cameras. I've used the Maplin ones in the past but they take a lot of current (relatively speaking) and awkward to control at a distance. I intend to give our CCTV security/livestock-watching system a going over later on. I reckon I can simplify things.

[nightfisher]

Finally got this thing attached to a scope! The small pulley and belt was purchased from:

motionco_Pulleys & Belts_Aluminium MXL Timing Pulleys_Buy Online

(Thanks to someone on SGL for recomending the supplier - btw exellent and quick service from them!). The bracketry was made by me.

The controller gives a rotation of the focusser from 1rev in about 12seconds to about 1 rev in 2 seconds. You can "blip" at slow speed to move the focusser knob somewhat less than 5° of a revolution at a guess - which should be fine enough. The little toothed belt is quite happy driving on the normal focusser knob and can be removed easily for "rough" focussing if required.

The only problem I can forsee is that by mounting the bracket on the tube ring I can't rotate the scope (as its a refractor that shouldn't matter) but it means that the finder bracket is now in an akward position and as I guide with the finder I may have to make a new arrangement for mounting this.

The controller now has two switches - one is the forward and back toggle and the second (on the end of the box next to where the wire comes out) is an on-off switch which I had to add as the power supply was running the batteries down even though the toggle was "off"! - it obviously still draws a small current somehow!

Bizibilder, i love it, so neat and tidy, i have a pair of servo`s to make the linked set up, i had an idea for mounting my focus servo but after seeing your set up i need to re think as mine would end up rough an ready, and a big thanks for the belt and pulley link,will be making this for my tal100rs

[yesyes]

Oh yes, thanks from me too for the link, Bizibilder.

I ordered a few timing belts and pulleys for my own motor focuser project.

yesyes DIY and astro :: Motor Focuser

Very honest company. Out of the blue they refunded me the postage cost a few days later saying that my order was large enough to qualify for free postage.

[Bizibilder]

Just had a flash of inspiration! (A VERY rere thing!) -

All you need to make a mount for the focusser that does not force you to have the finder at a silly angle is an extra tube ring! Put the focusser on its own dedicated ring and then you can use the scope "normally" in its own two rings. You may need to rebalance, but apart from that it should work?

Now, I wonder if FLO sell half a pair of rings??............

[nightfisher]

Just had a flash of inspiration! (A VERY rere thing!) -

All you need to make a mount for the focusser that does not force you to have the finder at a silly angle is an extra tube ring! Put the focusser on its own dedicated ring and then you can use the scope "normally" in its own two rings. You may need to rebalance, but apart from that it should work?

Now, I wonder if FLO sell half a pair of rings??............

yes im thinking along these lines, maybe we should go halves on a pair of 100mm rings and have one each

[nightfisher]

just an up date, my two servo`s are modded! i used acoms AS17 servo`s and they work a treat

[Bizibilder]

Can we have a Pic please?

[nightfisher]

so far just done the internal mods on these servo`s, removed all the circuit and altered the limiter gear, im waiting for drive belt and pulley cog to arrive also ordered some extension servo cables so i can wire them up with a plug connector.

Im so amazed how this works, turn the master servo and the focus slave servo follows it, fast or slow, very precise

[Bizibilder]

Looks and sounds like an interesting project.