Re: Regulated and unregulated ac adaptors.
- From: Johnny B Good <jcs.computersbutt@xxxxxxxxxxxxxxxx>
- Date: Sun, 22 Apr 2007 15:24:07 +0100
The message <462b5e87$0$21843$db0fefd9@xxxxxxxxxxxxxx>
from Linker3000 <linker3000@xxxxxxxxxxxxxxxxxxxxxxxxxx> contains these words:
DB. wrote:
I have a Belkin router that I recovered from a Council skip. TheYou've probably hit the nail on the head - the unregulated adaptors will
guy who put it there was so inconsiderate as to fail to leave the ac
adaptor, too.
This router, which takes 15v. DC (centre +ve), is at present
working perfectly well with a 15v. adaptor (borrowed short-term) from
the pack of a slightly-later Belkin router owned by my son. This
adaptor says "15v. DC" and the open circuit voltage is exactly that.
I have in my junk-box a couple of adaptors with a nominal 15v. DC
output but the o/c output of those is 21-22v. Is this a matter of
these being unregulated whilst that (Belkin) adaptor I have on loan is
regulated? Could I safely (wrt my router) use one of these two
adaptors?
--
TIA for any replies,
DB.
have a typical no-load voltage of 1.4 x stated output voltage. Whether
your Belink router will tolerate the brief over-voltage as they power up
is open to discovery and at your risk!
A lot of this type of kit (routers, switches) use switching regulators
to provide a stable 5v supply rail and avoid unnecessary heat
generation. Some even include a fullwave bridge rectifier and smoothing
cap (typically a 16v rated one) to allow an even cheaper plugtop
transformer (ac output) to be used.
Obviously, in this case, you _cannot_ use an ac output transformer
since the unit is clearly marked as requiring a 15v dc supply (with the
ac input types fitted with switching regulator, you can use either type
over a voltage ranging from 5 to 15 volt peak).
You can buy small general purpose plugtop smpsus with output voltage
selector switch that covers, typically, the range 3 to 12 volts at a
maximum output current of 1200mA. These come with a range of output
plugs which permit polarity reversal as required.
Even though the max voltage is only 12v, you can still experiment using
this type of unit to determine whether a switching regulator is being
used. If such is the case, you can power that belkin off pretty well any
voltage between 5 to 15 volts.
If you can measure the DC current draw, you will be able to observe a
negative current versus voltage loading characteristic as you try
different voltages if the device is using switching regulator technology
for its internal voltage rail(s).
Alternatively, you could feed it from a 6v dryfit lead acid battery or
a pair of such in series and measure the current consumption in each
case to confirm whether or not it's using switching regulator
technology. If it is, it'll work perfectly ok at both voltages at pretty
well the same power consumption regardless of voltage used.
HTH
--
Regards, John.
Please remove the "ohggcyht" before replying.
The address has been munged to reject Spam-bots.
.
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