[ARC5] Power Supplies for Your ARC-5

[David Stinson]

I'm sure that's correct.  All I know is if I hang 
200,000 ufds on the output of the supply I was using,
the dyno starts fine.  If I don't, the supply shuts down.
73 Dave S.

"J. Forster" wrote:
> 
> David Stinson wrote:
> 
> > The current ratings written on the dynamotors are the running currents.  The
> > starting surge current will be much higher.  I don't remember off hand what
> > the starting current for a DM-33 or DY-8 is, but I think it's around 25 amps.
> > Most of these supplies have protection against surges.
> 
> > You can overcome this by using some large capacitors in a bank to provide the
> > surge current, while the power supply
> > provides the running current.  24 volts in batteries will also work.
> 
> It will take a MIGHTY capacitor bank to start a dynamotor. Simply put:
> 
> Q (charge) = I (current) x T (time)
> 
> Q = C (capacitance) x V (Voltage)
> 
> therefore I*T = Q = C*V
> 
> in this case, the V is the allowable voltage drop during startup. Putting in
> reasonable numbers:
> 
> I =25 amps, T=1 sec, V=(28-23volts)=5
> 
> 25 * 1 = C * 5;  solving C = 5.............. FARADS, ie 5,000,000 microfarads.
> 
> That's a pretty big capacitor.
> 
> Think about floating batteres.. That's what I use for my No 19 MK III set, and
> it works just fine. Marine batteries in a fiberglass case are ideal.
> 
> Good luck,
> -John
> 
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