12 volt drive control, 110v AC motor
Posted 19 April 2019 - 12:28 AM
Problem is that they don't seem to make the traditional drive corrector anymore-- everything has gone over to GOTO systems and stepper motors.
Does anyone know of a source for Old School 12v drive correctors?
I've built a few from S&T projects, but I can't find my old schematics or notes. I've found only one project online, but it's been so long and I'm not sure it's the same. Does anyone know of a commercial unit or another schematic design?
Posted 20 April 2019 - 09:04 AM
There are plenty of 12v to 110v AC conversion products. They are generically called inverters ... the Orion product above is simply a battery packaged with an cheap inverter. There are a multitude of basic inverters which synthesize a partial sine wave AC output. When you run an AC motor on one of these partial sine wave products you will notice a bit more noise (usually a buzzing) and sometimes more heat from the motor.
There are also true sine wave inverters which much more closely create the same voltage characteristics that comes out of the wall. AC motors run much more smoothly on true sine wave inverters.
Most of the 12 to 110v AC converters/inverters (DIY instructions, kits, and those that came with the older mounts) made specifically for telescopes also include the ability to vary the frequency of the sine wave output (60hz +- a small amount). This ability to change the motor's frequency allows the mount's tracking rate to be modified. This is helpful for imaging (so corrections can be made when guiding) and high power solar and lunar work (so you can set a more accurate tracking rate and highly magnified lunar or solar features stay centered).
If you don't care about imaging or keeping highly magnified features centered then the ability to vary the frequency won't matter and a simple battery/inverter will be fine but personally with a fine scope like a Questar I would at least look into true sine wave inverters, it would put less stress on the motor. You likely will not find a combined packaged product like the Orion or many other automotive jump start type of batteries.
Posted 20 April 2019 - 07:34 PM
I have an old Celestron in working order if you are interested.
Edited by Spoonsize, 21 April 2019 - 12:34 PM.
Posted 20 April 2019 - 08:14 PM
I've designed several of them, some with microcontrollers and some without. PM me if you need references to them.