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Subject: Re: 24 VAC to 9VDC supply
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Date: Thu, 05 Dec 2002 04:00:56 GMT
NNTP-Posting-Date: Wed, 04 Dec 2002 23:00:56 EST
"Mark Lloyd" wrote in message
> On 4 Dec 2002 02:30:38 -0000, Steve W.EE
> >What is the quickest, dirtiest, cheapest way to get
> >9 volts DC from a 24VAC source.
> You won't need a transformer, but can connect the 24VAC directly to a
> > Need about 150ma
> >of current but the DC does not need to be regulated.
> >Half-wave rectifying will give too much DC voltage,
> >it would burn up a regulator since I don't have a
> >place to heatsink one.
> I doubt it. The power dissipated in the regulator is:
> Where Vi is the input voltage, Vo is the output voltage, and I is
> current. In your case.
> (Vi-Vo)*I = (24V-5V)*.15A = 19V*.15A = 2.85W
> Less than 3 watts isn't that much. You could even use one of the
> low-power regulators (78L05). These handle up to 150mA, are in TO-92
> cases, and don't use heatsinks.
> > Some solution which involves
> >cutting up a wall-wart making use of the parts inside
> >would be ideal.
> If you've got a regulated 5V wall-wart you don't mind cutting up.
> 21 days until the winter solstice celebration
> Mark Lloyd
> "There's no more proof for the existence of God than there is for the
existence of the
> Easter Bunny. That's right. The Easter Bunny."
That's why they call it, "Faith!"