low power degaussing coil
 

I've got a small 5" colour monitor that I'm using a test monitor. It
came with a small degaussing coil but no associated electronics.

This monitor will be moved around a lot and I don't want to have to
degauss it with a degauss wand every time it gets a bit magnitised. So
i'm trying to think of a way to power the coil it already has.

I'm thinking about putting a posister, the coil and a degauss button
in series with the 240v mains available inside the box. What type of
posistor to use? I imagine most would let too much current through
before getting hot enough.

Philips seem to have a large selection (availabe as tv spares) but I
can't find specs anyware online...

The coil is 140mm in diameter and has a DC resistance of 8 ohms

any ideas?

Tim Worthington writes:

I've got a small 5" colour monitor that I'm using a test monitor. It
came with a small degaussing coil but no associated electronics.

This monitor will be moved around a lot and I don't want to have to
degauss it with a degauss wand every time it gets a bit magnitised. So
i'm trying to think of a way to power the coil it already has.

I'm thinking about putting a posister, the coil and a degauss button
in series with the 240v mains available inside the box. What type of
posistor to use? I imagine most would let too much current through
before getting hot enough.

Philips seem to have a large selection (availabe as tv spares) but I
can't find specs anyware online...

The coil is 140mm in diameter and has a DC resistance of 8 ohms

any ideas?

Can't help with specs but all degaussing coils inside TVs and monitors
have a very low resistance and depend almost entirely on the Posistor
for current limiting to a safe value and of short duration.

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"Tim Worthington"

I've got a small 5" colour monitor that I'm using a test monitor. It
came with a small degaussing coil but no associated electronics.

This monitor will be moved around a lot and I don't want to have to
degauss it with a degauss wand every time it gets a bit magnetised. So
i'm trying to think of a way to power the coil it already has.

I'm thinking about putting a posister, the coil and a degauss button
in series with the 240v mains available inside the box.


** You need a bit more than that - usually a hefty relay is used to engage
the posistor circuit with a timer to hold it on for 5 seconds or so. The
button just initiates the timing cycle.


What type of
posistor to use? I imagine most would let too much current through
before getting hot enough.


** De-gaussing coil current peaks at around 30 - 50 amps.


Philips seem to have a large selection (availabe as tv spares) but I
can't find specs anyware online...

The coil is 140mm in diameter and has a DC resistance of 8 ohms


** Maybe just find an old PC monitor and remove one from it. But do not
just fit a simple on-off button or you will end up magnetising the tube very
badly.




............. Phil

Phil Allison wrote:
"Tim Worthington"

I'm thinking about putting a posister, the coil and a degauss
button
in series with the 240v mains available inside the box.


** You need a bit more than that - usually a hefty relay is used to
engage
the posistor circuit with a timer to hold it on for 5 seconds or so.
The
button just initiates the timing cycle.

I have Sanyo TVs built over 20 years ago that use nothing but a
posistor in series with the degaussing coil.

Phil Allison wrote:
"Tim Worthington"

I'm thinking about putting a posister, the coil and a degauss
button in series with the 240v mains available inside the box.


** You need a bit more than that - usually a hefty relay is used to
engage the posistor circuit with a timer to hold it on for 5 seconds or
so.
The button just initiates the timing cycle.

I have Sanyo TVs built over 20 years ago that use nothing but a
posistor in series with the degaussing coil.



** TVs are nearly all like that.

However, the OP has a portable monitor that may need to be de-gaussed
whenever it is moved about.

Hence the need for a "de-gauss" button.





.............. Phil