Re: TI-H: LED Backlight

Re: TI-H: LED Backlight

• To: <ti-hardware@lists.ticalc.org>
• Subject: Re: TI-H: LED Backlight
• From: "David Knaack" <dknaack@geocities.com>
• Date: Thu, 28 Jan 1999 09:47:53 -0600
• Delivered-To: ti-hardware-outgoing@towerguard.unix.edu.sollentuna.se
• Delivered-To: ti-hardware@lists.ticalc.org
• Reply-To: ti-hardware@lists.ticalc.org

From: Grant Stockly <gussie@alaska.net>
>>In the meantime, if anyone wants to use the current version [of
>>the autoswitch] it will work just fine if the first stage of the output 
>>is replaced with a darlington
>
>A 2N2222 will work fine.  It shouldn't use over 100ma.


It would work fine if transistors came with less variation in the
beta, however, that circuit is very sensitive to transistor beta,
not all transistors will work well, I'm estimating about 20% or
so (based on a sample of about 25) have high enough beta to
work in that circuit.  A darlington will work better, and the price
difference is negligible.

DK

• Re: TI-H: LED Backlight
• From: Grant Stockly <gussie@alaska.net>

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