[blazie-support] Re: Braille Lite Power Supply
- From: <louis@xxxxxxxxxxxxxxx>
- To: <blazie-support@xxxxxxxxxxxxx>
- Date: Tue, 13 May 2008 15:36:22 -0700
Hi. Are the specs the same for a Braille Lite 2000? Either we baught the wrong
chargers, or we got a dead unit that needs servicing, when the seller said it
powered up for them. HTH.
----- Original Message -----
From: Deborah Norling
To: blazie-support@xxxxxxxxxxxxx
Sent: Thursday, May 08, 2008 7:20 PM
Subject: [blazie-support] Braille Lite Power Supply
I posted a few weeks ago about needing the specs for the Braille Lite power
supply. I'd bought one on ebay surplus.
Here is a compilation of the information I received:
The BLT18 charger is a 12 volt, positive center, standard barrel plug
charger, with 800 miliamp current capability.
The BLT-40 units were similar, but require a full amp of current.
Radio Shack has 12 volt chargers that can supply 1 amp and have the right
type of plug and option to set for positive center. Many surplus vendors on the
net do as well.
This is usually a completely satisfactory charger for either the BLT-18 or
BLT-40, as long as you are sure to get the center pin positive polarity correct.
If the Braille Lite was sold or retrofitted after early 1999, it uses an
unregulated wall wart power supply to charge it's nicad battery pack. The
power supply has a 120 volt AC input and an unregulated dc output rated for 12
volts at 1 amp. This 12 volt at 1 amp output rating, is important because the
battery charging circuitry in the Braille Lite uses the voltage VS. current
curve of the unregulated dc output from this wall wart power supply, to sense
and control the level and depth of charge of the Braille Lite Nicad batteries.
This means that a dc output from this unregulated power supply, of let's say 13
volts, indicates a condition of charge to the Braille Lite circuits, and a 16
volt output from this unregulated wall wart power supply, means something
different to the Braille Lite circuitry controlling the charging of the Nicad
batteries. It's important therefore, to use a power supply that matches
closely the ratings of the wall wart power supply, originally provided with the
Braille Lite. Using a power supply with a 12 volt output and a lower current
rating, will not sufficiently charge the Braille Lite nicad batteries, and
using an unregulated power supply with a 12 volt dc output and a higher than 1
amp current rating, could overheat and posibly damage the Braille Lite nicad
battery pack, as well as other components in the Braille Lite charging
circuitry. You should only use the Braille Lite wall wart power supply, to
charge its nicad batteries for a maximum of five or six hours. If you leave
the wall wart power supply connected to your Braille Lite, for a longer period,
you risk burning out and overcharging the Braille Lite nicad batteries.
Braille Lite note takers sold before 1999 and not retrofitted, use a 9 volt DC
at 1 amp unregulated wall wart power supply to charge their Nicad Battery
packs. Again, it's important to replace the original wall wart supply with one
that has a very similar or identical output voltage and current rating. It
takes approximately 16 hours to recharge the nicad battery packs of older
Braille Lite units, using their older wall wart power supplies. You should
probably only leave these older Braille Lite units connected to their wall wart
power supplies for a day or so, if you want to prevent the risk of over
charging their nicad battery packs.
The wall wart power supplies for both the old and newer Braille Lite units,
have a coaxial 2.5 by 3 millimeter female plug to mate with the Braille Lite
charger jack. The center pin for all Braille Lite charger jacks is positive,
and the shell of the connector is negative.
The following is written on the wall wart for the BrailleLite M20.
Manufacturer: Condor
Phone: 408-745-7141
Model Number: d12-10-1000
specifications:
class 2 transformer
input 120 V 60 HZ 25 W
output 12 V DC 1000 MA
--Debee
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