Use for old linearity coil

[throbscottle]

Just fishing for thoughts here...

I have at least one old monitor linearity coil sitting in my junk box - I don't know much about these. Anyone got any suggestions for anything I could use it for? Or simple experiments I could rig to see the effect it has?

(comedy suggestions welcome!)

TIA

 

[ronsimpson]

I found that some work well in switching power supplies. The bias magnet, if used correctly, can cause the coil to work with almost 2X the current in one direction.

The magnet works on my refrigerator to hole notes.

 

[tcmtech]

I have an idea for where you can put it but someone else may not find it all that comfortable later!

 

[ronsimpson]

I have an idea for where you can put it but someone else may not find it all that comfortable later!

Where North Dakota?

 

[MrAl]

Where North Dakota?

Hi,

I have a feeling he meant further south (ha ha)

 

[alec_t]

You could build a pendulum clock and use the coil as an electromagnet to maintain the pendulum swing

 

[tcmtech]

I have a feeling he meant further south (ha ha)

Much further to the south and to the east a bit I think.
(But then I had suspicions at some points that he didn't know where he was or had been either so I could be wrong.)

Refresh my memory. What does the linearity coil do again? I don't remember much about CRT parts functions.

 

[ronsimpson]

Much further to the south and to the east a bit I think.
(But then I had suspicions at some points that he didn't know where he was or had been either so I could be wrong.)

Mcmtech made a crude comment about linearity coils. I was returning the comment about North Dakota as a unpleasant part of the world.
I remember the Dakotas as being colder than Alberta. On the first warm day flying bugs come out and make you pry for winter.
Whey they test for global warming they insert the thermometer into South Dakota.

Refresh my memory. What does the linearity coil do again? I don't remember much about CRT parts functions.

A linearity coil is a high current coil that is biased with a magnet. It sits in the current path of the horizontal deflection yoke. When drawing a picture on a CRT the electron beam is deflected by current (magnet field). The current is a function of supply voltage, inductance and time. The linearity coil is typically 20% of the total inductance. The linearity coil (adjustable or fixed) has a different inductance with + current compared to - current. Thus the inductance is different on the right hand side of the picture compared to the left hand side. The coil is adjusted so the picture's right/left sides (size) match.

 

[MrAl]

Mcmtech made a crude comment about linearity coils. I was returning the comment about North Dakota as a unpleasant part of the world.
I remember the Dakotas as being colder than Alberta. On the first warm day flying bugs come out and make you pry for winter.
Whey they test for global warming they insert the thermometer into South Dakota.



A linearity coil is a high current coil that is biased with a magnet. It sits in the current path of the horizontal deflection yoke. When drawing a picture on a CRT the electron beam is deflected by current (magnet field). The current is a function of supply voltage, inductance and time. The linearity coil is typically 20% of the total inductance. The linearity coil (adjustable or fixed) has a different inductance with + current compared to - current. Thus the inductance is different on the right hand side of the picture compared to the left hand side. The coil is adjusted so the picture's right/left sides (size) match.

Hi,

I have to laugh again about that comment:
"When they test for global warming they insert the thermometer into South Dakota."

How many turns does the coil have and what wire size approximately?

I have an old degaussing coil contemplating what to do with.

 

[ronsimpson]

I have an old degaussing coil contemplating what to do with.

Me to! Sent it to North Dakota.

Unfortunately I probably have the files to make more linearity templates. Not many people know what we are talking about.

 

[tcmtech]

Yea I know. Wife agrees I must have something stuck someplace being I am crabby today.

 

[throbscottle]

I found that some work well in switching power supplies. The bias magnet, if used correctly, can cause the coil to work with almost 2X the current in one direction.

Could this give improved load regulation?

As to where to stick it - south and a bit east for me would be somewhere in France...

 

[ronsimpson]

Could this give improved load regulation?

As to where to stick it - somewhere in France...

There are a number of 'mag amp' switching power supplies where the inductance is varied to regulate the supply.

I was thinking about the fact that most power supply inductors are used from 0 to 80% of saturation. The coil can work form -80% to +80% so only 1/2 of the coil is used. By biasing the coil so 0 current results in -80% saturation, then twice the normal current results in +80%. The core now can handle 2x the current.

 

[dr pepper]

I have a few of them.
And yes I have some pictures held to the fridge with a couple of the magnets.

I'm sure they'd cause a bit of a stir in the bedini pulse motor world, but that doesnt interest me.

 

[unclejed613]

int the 60's and 70's, there was a wah pedal called the Cry Baby. due to a manufacturing error, many of the inductors used in this pedal had a permanent magnetic bias in the core. this caused a slight amount of distortion in the output, and gave the pedal a distinctive sound. it seems to me a linearity coil core with a similar bias could be rewound to make a similar inductor and get the same sound (on purpose rather than by accident). on some linearity coils, the bias magnet can be moved to change the bias.

 

[dr pepper]

I repaired a few of those cry babies, they used rm series pot cores.