The Meade 1209 zero shift micro focuser (very difficult to find by the way, here’s the manual too) that I purchased was the latest version that did NOT have the handbox controller for it. The latest version is only compatible with the LX200 series where the 1/8th stereo jack of the focuser goes into the socket located on the mount of the telescope.
Well, that’s just f@#$%@#$ing fine and dandy, but most of the world does not own the LX200 series, we still have our original LX90’s that don’t have a port on the scope. Yes, if you are here, you probably have combed the web by now looking for this elusive handbox, or the APM that makes your LX90 able to handle extra accesories, but you’ve probably found that it’s next to impossible to find these items as they are indeed discontinued and there are scant few on the resale markets of ebay, cloudynights or anywhere else.
There are plans to make your own clone APM, there are JMI brand handboxes that fit this motor but cost $$$, and there is a plan to make a very basic controller with a DPDT switch out there, can’t relocate it… I needed something with push button controls, it is easier in my opinion to fine tune the motor’s position with buttons rather than sliding a switch, but, the switch allows you easily with less parts to change the direction of current… The circuit that works best for what I needed is the common transistor based H-bridge motor control that you’ll find everywhere online at various robotics forums. Basically, you’re making a motor go forward and reverse, but even a small motor can destroy your transistors with back EMF voltage spikes.
YOU NEED PROTECTION DIODES!!
And I have the circuit for you, CLICK to make it full size, as well as the design images, so please let send me a message if this helps, let me know what you build!
The above schematic needs the following components:
- 3.5mm stereo phone jack (female socket)
- R1, R2, R3, R4 = 1000 ohms each
- Switches are momentary push buttons
- L1 is the motor, please don’t put an inductor there…
- Q1, Q2, Q3, Q4 = NPN 2n2222 or 2n3904 , as long as your motor is relatively small and doesn’t require high current high voltage. These work fine for this focuser.
- D1, D2, D3, D4 = 1N4001 or 1N4148 or any rectifying diode, these are used just as protection to stop reverse voltage spikes, they don’t have to be high speed.
- Kit box was a SERPAC A231-bk case from fry’s
- 9 volt battery
- 9 volt battery cable
- perf board cut to size
The images below are the process by which I made the unit.
