wb lcd display

[Eric Bryant]

> From: rr [mailto:rrauscher at nni.com]
> Subject: Re: wb lcd display
> 
> 
> 
> For the 12 -> 5v p/s, I would do something close to how
> the WB UEGO circuit is powered. Just change the 78L08
> out for a run-of-the-mill 7805 regulator chip. Maybe add
> a 1N4001 diode in series with the input.
> 

I'd also recommend the addition of some capacitance to the input and output
of the regulator (at least a 0.1 uF on the input and output, and I'd
probably also put about an additional 10 uF cap on the output).  

In addition, place a transorb/zener diode in parallel with the input to
clamp the input voltage to ~30 V or so (if you can resist the temptation to
jump-start your car off a 24 V supply, feel free to clamp the input to 20 V
or so).  The series diode and the transorb really need to be used for any
in-car application, and this is pretty much bare-minimum for operation in a
vehicle with an internally-suppressed alternator.  It's probably not a bad
idea to put some small amount of series resistance in the input line,
either, but this depends greatly on the current demands of the display unit
(something like 5 ohms works pretty well with a small transorb, but the
wattage requirements get pretty big if the display unit draws any
appreciable amount of power).

Eric Bryant
mailto:bryante at ghsp.com
http://www.bryantperformance.com 

 

 
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