Re: plus4 power supply

Would it be possible to replace only the 7805 regulator with this RECOM 
R-78B5.0-1.5 ? (suppose that I can remove it from the resin)
Would it work with the resistor voltage divider on the output side?
That would maybe easier than to mount this DC-DC step down regulator...

Istvan

-----Original Message----- 
From: MarkoMäkelä
Sent: Thursday, September 20, 2012 9:43 PM
To: cbm-hackers@musoftware.de
Subject: Re: plus4 power supply

On Thu, Sep 20, 2012 at 05:31:42PM +0200, Gerrit Heitsch wrote:
>When I replaced the 7805 in my C16 with a switching regulator (*) and 
>removed R10, the current before the regulator went down to 380mA when 
>supplied with regulated 9V, with the original supply, it was 280mA since 
>that is about 11V. This meant a LOT less heat in the box.  Combined with 
>CMOS-EPROMs instead of NMOS-ROMs and heatsinks on CPU, TED and PLA, I hope 
>to have extended the livespan a fair bit.
>
>
>(*) RECOM R-78B5.0-1.5  drop in for a 7805.

RECOM recently introduced the cost-reduced E series that might work here
too. On my bicycle-dynamo-to-5V circuit it did not work well, because I
was feeding it too choppy voltage and it would only start up on every
4th to 10th half-wave. The R-785.0-0.5 works like a charm, with a
tolerable ripple voltage (120mV at 4.4V when charging my phone). When
connected to a more stable power supply, the ripple should be a few mV
at most, and I guess the output would stay closer to 5V.

Marko

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