RE: In car PSUs...

["Phil Harris" <phillip.harris1@xxxxxxx>]

Yeah ... I realised after talking with John that it was just a stepdown
regulator rather than an actual power supply capable of running off 4-15v.

I understand that Farnell do this kind of thing though ... does anyone have
a Farnell or RS catalogue that they could take a look in and see? Also, I
might need to buy a couple of very tiny Torx drivers and I think RS do
them - do you know whether they will sell to the general public at their
trade counters? (Theres one just down the road at Hedge End.)

Phil

> -----Original Message-----
> From: Keith Doxey [mailto:ukha@xxxxxxx]
> Sent: 08 August 2001 10:23
> To: ukha_d
> Subject: RE: [ukha_d] In car PSUs...
>
>
> 1. I think they need a better web/database designer for their online
> catalogue. The details it gave me were....
>
> Order Code: WC76H
> Output Voltage (V): 4.12
> Input Voltage (V): Jun-15
> Output Current (A): 3
>
> Exactly how many volts is the 15th of June and does the year affect
the
> current rating!!
>
> 2. No. It is a step down PWM regulator which works by turning the
output
> full on for a percentage of the time eg 1% = 1mS ON 99mS OFF, 50%
> = 50mS ON
> 50mS OFF. Very efficient for driving a motor but no good for much
else. It
> gives a short burst of the full battery power. You would need a
switchmode
> power supply to regulate the voltage. This has the ability to output a
> greater voltage than the input which could vary between  8 and
> 14V (starting
> the engine and fully charged battery). A conventional linear power
supply
> needs an overhead of about 3 volts to operate properly so to guarantee
a
> rock steady 12V you would need a minimum of 15V.
>
> Keith
>