Flourescent bulbs

[Chris Smith]

Robert, <p>My Nearest neighbor cant yell that far? <p>Either that Or I cant hear him?<p>Two miles is just past a 22s maximum range by at least double. <p>But I do remember the city one time and the neighbors back door glass,.... and a sub [BB] machine gun that went astray. <p>5000 BBs a minute, and some just had to go astray? <p>You could see them like a cue ball hit with a curve shot going around a corner! <p>50 bucks worth of lessons?

[peter-f]

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by Chris Smith:
... However, like all noise circuits you have to start at the beginning.<p> Shield the ballast unit using lots crude foil to a good earth etc, to see if its RF is into the Air waves or not, and if not then line conditioners, also RF foil shielded to earth to stop any leaks there also.<p> You must determine if its line or air leaks, and then deal with them accordingly. <p>Each “type” of RF has a different way of quenching them.<hr></blockquote><p>
well, Chris... the RF was definitely through the line... picked up by a short wave receiver on another circuit. Nothing to do with audio noise!<p>Still... cheap dimmers (for incandescents) and many new ballasts are also RF noise sources...
Thus, my question.

[dacflyer]

AL WARNER >> i know its illegal but it worked then,, i have since rewired my shop..and all is normal now, so no worries... i was simply stating that it does work when in a pinch....illegal or not. they are physically same points in the breaker box.

[Chris Smith]

Line filtering is a science. To simply describe some type of answer, most likely will only suppress some of the noise. To do a full job you need a scope and some other equipment to determine what frequencies you are dealing with. <p>Several ways to quench line frequency is through the use of simple caps, chokes, and coils, dumping or clamping them to ground very near the source. <p> This is passive filtering. <p>Often you need active filters, such as creating a back flow of the same type of signal, to cancel out the original. <p>A good book on line filtering is suggested, especially if you don’t have the lab equipment, or experience in this field. <p>With me, it was always “experiment” using know values and Ideas, and then check to see how well you canceled a signal. <p>Chokes and coils take RF and tend to weigh them down, and often turn it into simple energy that can be suppressed. <p>Diodes, caps and other methods allow the signal in the line to be “decoupled” and thus the original line power is not shorted to ground while the RF is.<p>[ July 28, 2005: Message edited by: Chris Smith ]</p>

[Edd]

Peter-f:
I have experienced interference from the new SS ballast units in two ways. That being when I am either tuned to the AM mode on SW radio/Ham bands or am viewing a TV with a marginal/weaker signal input such as one might expect when utilizing rabbit ears.
On the radios received RFI, it's the typical fast grinding static or occasionally a birdie type of squeal if it happens to be tuned in so as to be heterodyning with a frequency. On the TV screen, TVI shows up as a multiple laterally spaced out series of white vertical S shaped dotted lines. The lamp electronics was definitely its source, by a confirmation after turning the unit off. The unit happened to be installed in a lamp stand so a bit of room was available in the lamps base area. Also some degree of shielding to the AC line routing was automatically provided through the vertical metal stem of the lamp support. Plus, the lamp shade did happen to be of a metalized Mylar type of material, which did help also in further shielding action of the lamp proper. I did install an adequately small alum mini box to permit the passage of the POSJ lamp cord in thru a grommet and then divide it into its two conductors with the looping of each wire thru its individual ferrite “RFI” toroid, threading in as many turns as the cores center dia could accommodate. Then the wire was “re-paired” so that a longer tubular style of ferrite core then had both of those wires passing thru it. The wire pair was connected to a set of terminal strips in either side of the ferrite filters so that a .1ufd disc ceramic could be installed both across the wire pair and from each individual wire to ground, such that bypassing was done before and after the ferrite donuts with a grounding being made to the lamps metal base as well as the minibox. Therefore, a total of 6 ceramic bypassing caps were used. A final installation of a replacement line cord with a polarized plug then assured that …gnd would be gnd in its hookup.
The end result was that I could have an AC powered AM radio plugged into the same outlet and only start any picking up of hash when I had approached the lamp until it was ≈ 1 ft from the radio or 2 feet if I peaked its ferrite antenna rod broadside….I could then live with that.
On the TVI situation I found it necessary to go into the lamp proper via Zona razor saw access thru the small center ultrasonically bonded seam in its polyvinyl casing…..I was curious about its internal design anyway.
The unit used two bipolar switching transistors Motorola 13009 …within the TO220 profile of housing. What I eventually came up after repeated modifications-tests and samplings of resultant RFI radiation was the installation of mini cylindrical RFI beads on the collector and base leads of the transistors.They are right at the dia sizing of an old Allen Bradley carbon comp res, and 1/3 its length with an ≈ 1/16 center hole. With the necessity of a Dremel cutoff wheel squaring off of the leads where they widen out up near the case, in order to get the beads as close as possible to the case. I no longer have TVI.
Strangely enough, in evaluating some newer units that my son started using, seems like the newer designs are not now quite the offending RFI radiators that the older design units were.<p>WILL:
"I was in Sapin about that time."...as in Spain ...o... Espana?
If you have ever just taken a scope and triggered on and watched, you will see multiple spikes and aberrations created in a mechanical switch on just a DC switching . However if you were to observe the gradual opening of that bimetallic switch, its for sure that multiple firings do slip through that time window, or if for some reason it doesn’t start up, the unit is then going to initiate another start up process. On your pushbutton starting, you must have overlooked that schemas simple pushbutton starter mode, which was in the top diagram in the bottom right quadrant.<p>73’s de Edd
[email protected] .........(Interstellar~~~~Warp~~~Speed)
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<p>[ July 28, 2005: Message edited by: Edd Whatley ]</p>

[rshayes]

Look at the surplus sources for the packaged EMI filters used with switching power supplies. These usually have two or three capacitors and a couple of chokes in a small metal can. The important thing is that the capacitors are rated for AC line use (usually ceramic at a thousand volts or more). These capacitors arn't particularly common by themselves. The entire assembly usually has UL and other approvals.<p>New units may be available from distributors such as Allied, Digi-Key, Mouser, or Newark. <p>Look up Corcom or Spectrum Control for typical data sheets on these filters.<p>[ July 28, 2005: Message edited by: stephen ]</p>

[Chris Smith]

A lot of the over the counter type filters don’t work well with HF feedback. At a shop that I worked, the RF from a Mig welder feed back into the 240 lines over three hundred feet and fried my monitor. <p>I had installed a "over the counter" filter, and it did get rid of some of the RF that caused the monitor to be unreadable, but it only picked on certain frequencies. Harmonics are hard to squash.<p>That’s why a scope comes in handy, you find the offending frequency and pick on it directly. BUT, you can always get lucky, and pre-made filters for the most part are worth their weight in gold, and time.

[jollyrgr]

Maybe this has been answered somewhere but I missed it. There was a side discussion about how to get rid of old flourescent bulbs. One thing I wondered was why they need to be made of glass? I know there is a heater element at each end of the tube. But why could this not be a ceramic type end cap inside a clear plastic PVC tube of some sort? Much safer than glass when dropped. Even if it meant giving up an inch or so at each end of light emission, I think using plastic tubes would be cheaper and safer than glass but know there must be a reason this is not being done. Any ideas?

[peter-f]

Thanks guys... lots of direction here.
As further background, If I recall, the 'hum' that was caused by my old fluorescent was recognized by my dad (an audio/electronics engineer) as 60Hz... so his solution was a Cap across the ends of the bulb.
[referring to Edd's schematic] from 1 end of the AC power supply - to the end of the ballast winding on the opposite leg of the supply...
roughly the same as the Blue line.<p>Also- your experiences parallel mine... reception OK unless <2 feet from lamp; Cap was rated high... 1000V ceramic... unknown UF rating.<p>I don't recall whether the initial connection was trial-and-error to find the "Live" wires... so long ago, and how Much we forget!<p>Thanks again... helps to reinforce the concept before wasting time on such projects.<p>[ August 01, 2005: Message edited by: peter-f ]</p>