Looking for direction

[Ian Sutherland]

Hi folks, I need some direction in diagnosing a condition that I have
created. I wanted to install a 2 Kw. fan heater under my computer
desk, didn't want to have just high & low settings, but wanted the
heat to be continuously variable.

I have built up a circuit that works really great, stepless control
from off (actually 1 cycle every 3 seconds, to full on) The problem is
that now the monitor "Jitters."

The control is a SSR driven by a 555. The SSR has built in zero
crossing detection, the 555 outputs a pulse about 8 ms long to trigger
the relay & a repetition rate adjustable from about 3 seconds down to
about 10ms (to switch the relay on every cycle.)

I thought it might be the current surges causing the jitter, but I'm
sure thats not the case. The jitter remains the same whether the
element is being pulsed at 3 second intervals, or is on continuously.
(This would be the same as the heater prior to the mods.)

The heater has a built in thermostat that I left in & this is in the
neutral line, so I turned it down 'till the elemnet swiched off, the
jitter remained. I guess it's coming from the 555 switching (maybe the
8 ms. pulse) & perhaps ferrite beeds will cure it.

I would be interested to hear any coments regarding fixing the
problem

T.I.A. Ian Sutherland.

Since re-reading the above, maybe the short pulse is not the
culprit, with the elements off (T/stat turned down) & the pot set to
off (1 pulse every 3 seconds) the jitter remains constant, about 2 or
3 cycles per second. Ian S.

 

[Allen Greb]

magnetism give up now while you are in front for your health and monitor.

use a heat lamp 275w with standard BC base and Clipsal light dimmer
works a treat and have used it for years.

 

[Ian Sutherland]

magnetism give up now while you are in front for your health and monitor.

use a heat lamp 275w with standard BC base and Clipsal light dimmer
works a treat and have used it for years.

Hi Allen, thanks for the quick response. I'm not sure how you did
that. I logged on 9:00 am & my original post wasn't up. 10 mins later
my post was visible & so was your reply. If it takes 6 to 9 hours to
display the original, doesn't it take a similar time for susequent
replies ??

Getting back to the problem, I had found it by the time I saw your
reply, you hit the nail on the head. It's the field from the squirrel
cage fan motor!!!!!

B.T.W. please explain the health comment.

My dog kennel is heated with a heat lamp, time clocked on about 6:00
pm (in the winter) full power for 1/2 hour then set by a dimmer 'till
8:00 am. been that way for years.

Thanks again, just have to find a large chunk of Mu metal.

Ian Sutherland.

 

[Phil Allison]

"Ian Sutherland"

Hi folks, I need some direction in diagnosing a condition that I have
created. I wanted to install a 2 Kw. fan heater under my computer
desk, didn't want to have just high & low settings, but wanted the
heat to be continuously variable.

I have built up a circuit that works really great, stepless control
from off (actually 1 cycle every 3 seconds, to full on) The problem is
that now the monitor "Jitters."

The control is a SSR driven by a 555. The SSR has built in zero
crossing detection, the 555 outputs a pulse about 8 ms long to trigger
the relay & a repetition rate adjustable from about 3 seconds down to
about 10ms (to switch the relay on every cycle.)

** Why the heck did you use a stupid zero crossing SSR ??

A phase controlled triac ( ie a hefty dimmer) is the go - the fan motor
will run properly too.





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

 

[Ian Sutherland]

** Why the heck did you use a stupid zero crossing SSR ??

Because I had it.

A phase controlled triac ( ie a hefty dimmer) is the go - the fan motor
will run properly too.

The fan motor runs fine as it is accross the mains whenever the heater is on.

B.T.W. I've repositioned the heater, the monitor is fine & my feet are warm.

Cheer's, Ian Sutherland.

 

[Phil Allison]

"Ian Sutherland"

Because I had it.

** Friend of Sir Edmond by any chance ???

The fan motor runs fine as it is across the mains whenever the heater is

on.


** It damn well does not run fine with only a few cycles out of 50 arriving
every second !!!!!

BTW How are your bug, rodent and pipe scale frighteners all going ???

B.T.W. I've repositioned the heater, the monitor is fine & my feet are

warm.


** Why not use an old fashioned hot water bottle - low tech is great
you know.




.......... Phil

 

[Rod Speed]

Hi folks, I need some direction in diagnosing a condition that
I have created. I wanted to install a 2 Kw. fan heater under
my computer desk, didn't want to have just high & low
settings, but wanted the heat to be continuously variable.

I have built up a circuit that works really great, stepless
control from off (actually 1 cycle every 3 seconds, to
full on) The problem is that now the monitor "Jitters."

You'll almost certainly find that you get that shimmy even with
just the fan heater, no control at all. Its just the magnetic field
from the heater itself getting into the monitor.

I get that effect myself, with no control on the
fan heater, if its close enough to the monitor.

 

[Rod Speed]

magnetism give up now while you are in front for your health

Wont do your health any harm.

and monitor.

Or the monitor either. Its just a cosmetic effect.

use a heat lamp 275w with standard BC base

Nowhere near hot enough here.

 

[Ian Sutherland]

** It damn well does not run fine with only a few cycles out of 50 arriving
every second !!!!!

BTW How are your bug, rodent and pipe scale frighteners all going ???



warm.


** Why not use an old fashioned hot water bottle - low tech is great
you know.




......... Phil

Phil, I never thought you would be the type to post a reply without
correctly reading the text!!!

on.

To make myself clearer, the fan is not controlled by the SSR.


** Friend of Sir Edmond by any chance ??? Hillary? Never met the
man.

I'm typing this at my daughter's, the next job is the installation of
the water pipe descaler. Oh well it's her money.

Cheer's Ian Sutherland.

 

[Phil Allison]

"Ian Sutherland" <[email protected]

Phil, I never thought you would be the type to post a reply without
correctly reading the text!!!

To make myself clearer, the fan is not controlled by the SSR.


** Friend of Sir Edmond by any chance ??? Hillary? Never met the
man.

I'm typing this at my daughter's, the next job is the installation of
the water pipe descaler. Oh well it's her money.

Cheer's Ian Sutherland.

** Ian - why on earth did you chop my post up, re-arrange the order of
the sentences and take out some of your words so my reply to them had no
context ???????

That is *not* good usenet etiquette.




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

 

[Ian Sutherland]

"Ian Sutherland"


** Friend of Sir Edmond by any chance ???



on.


** It damn well does not run fine with only a few cycles out of 50 arriving
every second !!!!!

BTW How are your bug, rodent and pipe scale frighteners all going ???



warm.


** Why not use an old fashioned hot water bottle - low tech is great
you know.




......... Phil

O.K. Phil. NO flame wars, The chop up was to save you reading type
that had no bearing on the re-post. HOWEVER, I will reply to your
unsnipped post & CLEARLY you will see that you made an incorrect
assumption.

I said "The fan motor runs fine as it is across the mains whenever
the heater is

on."

You said "** It damn well does not run fine with only a few cycles out of 50 arriving
every second !!!!!"

Surely you can see that if it's across the mains, it can't have the
SSR in series with it.


The parts about Sir Edmund & the pipe descaler have no bearing on the
present discussion.

I fail to see what parts I removed from your post that caused anything
to be taken out of context. BUT, I'm quite able to take any criticism
for my errors & would be only too pleased to learn how to post in a
more acceptable manner.

I don't wish this to go on & on, I just want you to admit that you
were wrong <G>

Cheer's, Ian Sutherland.

 

[Phil Allison]

"Ian Sutherland" <

"Phil Allison" <

O.K. Phil. NO flame wars, The chop up was to save you reading type
that had no bearing on the re-post.

** Do not chop someone's post up and alter the order of things - that is
a bizarre thing to do.

HOWEVER, I will reply to your
unsnipped post & CLEARLY you will see that you made an incorrect
assumption.

I said "The fan motor runs fine as it is across the mains whenever the heater is


Surely you can see that if it's across the mains, it can't have the SSR

in series with it.


** Your wording is ambiguous - it *can* be read that as the heater (ie
the wire element ) is only on by virtue of the SSR so the the fan is on at
those same times as well.

The parts about Sir Edmund & the pipe descaler have no bearing on the
present discussion.

** Why did Sir Edmond climb Mt Everest ..... " because it was there " he
famously said.

Why did Ian Sutherland use a SSR ..... " Because I had it. " you
posted here.

See any similarity in the two whys ?????

( Your use of the SSR and the pipe descaler business are also similar -
as devices that are ill suited to the actual task.)

I fail to see what parts I removed from your post that caused anything
to be taken out of context.

** You removed your words my response was directed to which made my ironic
question look incomprehensible - then you posted a literal reply. The
seemed to be the direct result of your context erasure and re-arranging my
post.

BUT, I'm quite able to take any criticism
for my errors & would be only too pleased to learn how to post in a
more acceptable manner.

I don't wish this to go on & on, I just want you to admit that you
were wrong <G>

** You have cleared up the ambiguity now.



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