Last updated: 21 June 2002

Another ETX-70AT Power Supply

Subject:	Yet another power supply for ETX 70
Sent:	Wednesday, June 19, 2002 3:13:01
From: (bob greef)
The six AA Batteries just don't last long enough on the ETX 70, I have
had pointing accuracy problems with both NiCD and NiMH rechargables as
they only deliver 1.2 Volts each and a mains adapter is of very little
use in the field.

My own solution is a small 12 volt sealed lead-acid battery connected to
the ETX via a regulated DC-DC converter that supplies a range of
voltages from 3V to the full 12V.

The connection to the ETX is via a standard 2.5mm power plug that plugs
into a standard 2.5mm socket fitted to the lid of the battery

The socket is in turn connected to the normal ETX battery connector via
a further PP9 type connector.

This all means that the only alteration required to the telescope itself
is the drilling of a small hole in the battery compartment lid to accept
the 2.5mm socket.

Removal of rhe battery compartment lid allows a return to normal six X
AA batteries use if required.

I have been using this mod since January with no problems, the
converter, plug and socket, lead-acid battery and various connectors are
all available off the shelf, (in the UK at Maplins Electronics but I am
sure that Radio Shack would carry a similar range)total cost about 20
UK including the battery.

I usually just sit the Battery and Converter on the Eyepiece tray during

I would recommend frequent checking of polarity during assembly, I used
a cheap multimeter.

Photographs attached which may explain better.

Hope this helps someone: Super Site!

Bob Greef
Norwich England
power supply

power supply

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