Re: plus4 power supply

From: Gerrit Heitsch <>
Date: Thu, 20 Sep 2012 21:56:38 +0200
Message-ID: <>
On 09/20/2012 09:43 PM, Marko Mäkelä wrote:
> 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.

Depends... The C16 needs close to 1A on 5V with the NMOS-ROMs, so to be 
on the safe side, I decided to use the 1.5A version.

> 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.

That one is only good for 0.5A. Would be perfect for use in a C64 to 
replace the onboard 7805 though. But only if the ripple is really low 
enough so it doesn't show on the output signals since this regulator 
supplies VIC.


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Received on 2012-09-20 20:00:54

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