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As you can see in the picture, the switch is set to the off position.
When I test the continuity, there is no beep.
However, when I test the outgoing voltage, it is 18 Volts D.c.
What gives?
"https://www.dropbox.com/s/sngn1wyod4ni19i/Switch.jpg?dl=0"
That switch looks like it is on the mains? AC input? Capacitors onOn Friday, April 5, 2019 at 4:09:16 PM UTC-5, AK wrote:
As you can see in the picture, the switch is set to the off position.
When I test the continuity, there is no beep.
However, when I test the outgoing voltage, it is 18 Volts D.c.
What gives?
"https://www.dropbox.com/s/sngn1wyod4ni19i/Switch.jpg?dl=0"
On further testing, I found that the transformer holds a residual charge for a few minutes after it is unplugged.
Is it because of some capacitors in the transformer?
On Fri, 5 Apr 2019 14:26:15 -0700 (PDT), AK <scientist77017@gmail.com
wrote:
On Friday, April 5, 2019 at 4:09:16 PM UTC-5, AK wrote:
As you can see in the picture, the switch is set to the off position.
When I test the continuity, there is no beep.
However, when I test the outgoing voltage, it is 18 Volts D.c.
What gives?
"https://www.dropbox.com/s/sngn1wyod4ni19i/Switch.jpg?dl=0"
On further testing, I found that the transformer holds a residual charge for a few minutes after it is unplugged.
Is it because of some capacitors in the transformer?
That switch looks like it is on the mains? AC input? Capacitors on
the transformer secondary can't impose a DC voltage on the primary
side.
What are you using to measure this DC voltage? Something hinky is
going on and perhaps a high impendence meter is just responding to
electrostatic charge in the area.
As you can see in the picture, the switch is set to the off position.
When I test the continuity, there is no beep.
However, when I test the outgoing voltage, it is 18 Volts D.c.
What gives?
"https://www.dropbox.com/s/sngn1wyod4ni19i/Switch.jpg?dl=0"
That's quite possible with input filters on the power line. They canOn Friday, April 5, 2019 at 5:03:01 PM UTC-5, default wrote:
On Fri, 5 Apr 2019 14:26:15 -0700 (PDT), AK <scientist77017@gmail.com
wrote:
On Friday, April 5, 2019 at 4:09:16 PM UTC-5, AK wrote:
As you can see in the picture, the switch is set to the off position.
When I test the continuity, there is no beep.
However, when I test the outgoing voltage, it is 18 Volts D.c.
What gives?
"https://www.dropbox.com/s/sngn1wyod4ni19i/Switch.jpg?dl=0"
On further testing, I found that the transformer holds a residual charge for a few minutes after it is unplugged.
Is it because of some capacitors in the transformer?
That switch looks like it is on the mains? AC input? Capacitors on
the transformer secondary can't impose a DC voltage on the primary
side.
What are you using to measure this DC voltage? Something hinky is
going on and perhaps a high impendence meter is just responding to
electrostatic charge in the area.
Using a digital multitester.
I hooked up a 12 volt led bulb to the output.
When the switch was turned off, it glowed for about 20 seconds and then faded to no light.
Andy
On Fri, 5 Apr 2019 15:25:48 -0700 (PDT), AK <scientist77017@gmail.com
wrote:
On Friday, April 5, 2019 at 5:03:01 PM UTC-5, default wrote:
On Fri, 5 Apr 2019 14:26:15 -0700 (PDT), AK <scientist77017@gmail.com
wrote:
On Friday, April 5, 2019 at 4:09:16 PM UTC-5, AK wrote:
As you can see in the picture, the switch is set to the off position.
When I test the continuity, there is no beep.
However, when I test the outgoing voltage, it is 18 Volts D.c.
What gives?
"https://www.dropbox.com/s/sngn1wyod4ni19i/Switch.jpg?dl=0"
On further testing, I found that the transformer holds a residual charge for a few minutes after it is unplugged.
Is it because of some capacitors in the transformer?
That switch looks like it is on the mains? AC input? Capacitors on
the transformer secondary can't impose a DC voltage on the primary
side.
What are you using to measure this DC voltage? Something hinky is
going on and perhaps a high impendence meter is just responding to
electrostatic charge in the area.
Using a digital multitester.
I hooked up a 12 volt led bulb to the output.
When the switch was turned off, it glowed for about 20 seconds and then faded to no light.
Andy
That's quite possible with input filters on the power line. They can
remain charged after power is disconnected. An interesting experiment
would be to take multiple readings after switching off a number of
times and seeing what voltage you get each time.
Discharge the cap with the LED each time and you should see a
different voltage and possibly a different polarity each time. The
voltage should be dependent on where (at what point) on the input sine
wave you break the connection.
Another pretty good possibility is a switching power supply. I
discounted that idea originally because the switch looks ancient.
(before SMPs became prevalent) Switchers often charge a cap from the
mains and you could see some leakage from the diodes charging the cap.
With a switcher the transformer is after a largish electrolytic cap
that is charged directly off the mains. If that were the case, I'd
expect the DC voltage to be dependent on the amount of leakage in some
diodes over others and should be relatively the same each time you
switch it off until the charge on the cap leaks off.