7 Feb
2009
7 Feb
'09
2:38 p.m.
Subject: Re: Anyone have a line on batteries for the NLS
From: ard at p850ug1.demon.co.uk (Tony Duell)
Date: Sat, 07 Feb 2009 19:32:31 +0000 (GMT)
To: cctalk at classiccmp.org
For the NLS 'scopes the battery is between the charge source and the
scope power supply so if it's open (badly sulfated as the battery is
lead acid gell type) the PS has to carry the load. It's only a charger.
if you substitute a larger charger then you find the charge circuit
does not have the capacity to start the unit (initial surge current).
On Thu, 5 Feb 2009, Allison wrote:
That's quite common with devics powered with rechargeable batteries --
the charger on its own can't supply enough current to run the device. The only reason batteries are needed to run the
NLS is the charger is way
too small run run it directly.
I found THAT out the hard way.
When I sold my NLS215 at VCF, I had to sell it "AS-IS" because the
batteries wouldn't take a charge. Assuming the battery pack is just a battery (that is,
no 'battery
management' circuitry), you can often run the unit from a bench power
supply connected to the battery wires _with the battery disconnected_. Of
course this assuems you have a suitable PSU...
The pack in this case is just 3 2v cells and the "management" is the
charge circuit on the rear board.
In this case (nls miniscopes) a 6V PS can substitute for the battery at
less tha 1A (must be connected to the ground and +6V termianls of the
battery connection point internally). Only if the battery is removed first.
Note that is the battery has failed (usually sulfated from not being kept
charged) they tend to build corrosion around the terminal, they are best
removed and recycled as any gelled lead acid battery should be.
Since I use my miniscopes intermittently I've long since removed the
battery and disconnected the internal charge circuit (pull the fuse).
The battery area has a small board inserted to allow it to accept any
voltage from 9 to 30V and run from that. Since I have a number of small
12V gell cells that fit nicely in the probe pocket of the carry case
this proves more useful and maintainable. The change is completely
reverseable and the ability to use a larger and longer lasting 12V
battery as source is very handy.
The NLS is somewhat unique as it uses a lead acid type rather than NiCd,
Nimh, lithium or even common dry cells. In an emergency I have run it
off 4 'D" sized alkaline cells in an external holder for many hours.
Allison