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Homemade Hand Controller

The Meade LX10 hand controller costs about £69 in the UK - far too excessive! Fellow LX10 owner, Han Kleijn, took his apart and drew up notes of his interpretation of the hand controller's schematic and published this on his website. From these notes I built my own hand controller and introduced 4 ultra-bright red LEDs for night light illumination. I bought all parts from Maplins (except the coiled cable) and it cost me about £15 to construct.

The hand controller provides 2x sidereal rate on the RA motor drive (it simply turns the motor off to track east and doubles its speed to track west), and the optional Dec motor (which I will buy one day...). This is essential for long exposure photography.

Here follows a schematic of my hand controller:

The switches that I've used are toggle switches. I couldn't find push button switches cheap enough which had a single pole double throw action. If you decide to use my circuit design please be aware of the resistor values of the LEDs. The resistor value R is calculated using the following formula

R = (Vs - Vd)/I

Where Vs is the power supply voltage, Vd is the LED's forward voltage and I is the diode's normal operating current. The connector to the telescope is an FCC68 module plug with 6 slots and 6 pins (same american telephone plugs, similar to computer network cable plugs). Here is a simple diagram of the plug which shows the designation of the pins: