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#1
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Hum from the transformer in power supply
I am assembling an amp and have a nice transformer of proper VA rating.
This transformer is an EI type transformer, with laminations. But, this transformer has no bells on both sides to cover the windings. Without the bells will I have hum problems when the transformer is installed within 4 inches of the low level circuit cards that drive the output MOSFETs? I can orient it so the laminations "point" to the amp's active circuitry but the sides where bells usually go will then be "pointing" at the filter capacitors. Will this orientation be OK in the amp and not make it hum? Can someone give me some good advice on this and/or point me to a good web site that discusses transformer hum or eddy current? Thanks a lot. |
#2
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Hum from the transformer in power supply
The filter caps will not be sensitive to the orientation of the transformer.
If you cannot get it right, why not mount it externally in its own separate case? I have seen a number of high end amplifiers with the power supply outboard. You can make a nice wire harness with connectors on it to have it detachable for transport, or relocation of the amp. -- Greetings, Jerry Greenberg GLG Technologies GLG ========================================= WebPage http://www.zoom-one.com Electronics http://www.zoom-one.com/electron.htm Instruments http://www.zoom-one.com/glgtech.htm ========================================= wrote in message ... I am assembling an amp and have a nice transformer of proper VA rating. This transformer is an EI type transformer, with laminations. But, this transformer has no bells on both sides to cover the windings. Without the bells will I have hum problems when the transformer is installed within 4 inches of the low level circuit cards that drive the output MOSFETs? I can orient it so the laminations "point" to the amp's active circuitry but the sides where bells usually go will then be "pointing" at the filter capacitors. Will this orientation be OK in the amp and not make it hum? Can someone give me some good advice on this and/or point me to a good web site that discusses transformer hum or eddy current? Thanks a lot. |
#3
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Hum from the transformer in power supply
"Jerry G." wrote in message ... The filter caps will not be sensitive to the orientation of the transformer. If you cannot get it right, why not mount it externally in its own separate case? I have seen a number of high end amplifiers with the power supply outboard. You can make a nice wire harness with connectors on it to have it detachable for transport, or relocation of the amp. On the other hand you can see plenty of high end gear with power transformers right next to low-level circuitry, and no problems. Suck it and see - plonk it in there and move it around.... geoff |
#4
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Hum from the transformer in power supply
Geoff Wood wrote: "Jerry G." wrote in message ... The filter caps will not be sensitive to the orientation of the transformer. If you cannot get it right, why not mount it externally in its own separate case? I have seen a number of high end amplifiers with the power supply outboard. You can make a nice wire harness with connectors on it to have it detachable for transport, or relocation of the amp. On the other hand you can see plenty of high end gear with power transformers right next to low-level circuitry, and no problems. Suck it and see - plonk it in there and move it around.... geoff The point here is that the EI transformer I have has NO BELLS on the two sides where the windings are exposed. Most transformers have bells and, yes, are tucked right in close to the low level circuit cards in an amp, although these transformers are usually oriented so the laminations "point" to the circuit cards and the bells are at a right angle to them. My concern is the amount of eddy current that escapes from the trans. that has no bells. I was hoping somebody could point me to a good article or whatever about this. Bells are put on transformers to hold in the eddy currents and to shield surrounding circuitry from the influence of eddy currents. Well, in the absence of some good info I will just have to wing it and try the empirical approach, or maybe cover the transformer with a tin can. |
#5
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Hum from the transformer in power supply
wrote in message The point here is that the EI transformer I have has NO BELLS on the two sides where the windings are exposed. Most transformers have bells No they don't. Some do, some don't. Some have an effect, others don't. More to do with the surropund components, impedences, and topography. and, yes, are tucked right in close to the low level circuit cards in an amp, although these transformers are usually oriented so the laminations "point" to the circuit cards and the bells are at a right angle to them. My concern is the amount of eddy current that escapes from the trans. that has no bells. I was hoping somebody could point me to a good article or whatever about this. Bells are put on transformers to hold in the eddy currents and to shield surrounding circuitry from the influence of eddy currents. Well, in the absence of some good info I will just have to wing it and try the empirical approach, or maybe cover the transformer with a tin can. I'm sure you are anticipating a problem that probably won't exist. Only way to know for sure is to try it. geoff |
#6
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Hum from the transformer in power supply
"Geoff Wood" wrote ...
Bells are put on transformers to hold in the eddy currents and to shield surrounding circuitry from the influence of eddy currents. Do you have any support for that statement? I've never heard anyone propose such a thing before. |
#8
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Hum from the transformer in power supply
Thanks to all of you for your responses. I have learned a few things.
Solution? Put the parts on a breadboard and try it. . . . |
#9
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Hum from the transformer in power supply
Richard Crowley wrote:
Bells are put on transformers to hold in the eddy currents and to shield surrounding circuitry from the influence of eddy currents. Why do you say that? Gib |
#10
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Hum from the transformer in power supply
Richard Crowley wrote:
Bells are put on transformers to hold in the eddy currents and to shield surrounding circuitry from the influence of eddy currents. "Gib Bogle" wrote ... Why do you say that? I DIDN'T say that. (Note the triple ) "Geoff Wood" said it. I DISPUTED that and the "Geoff Wood" hasn't responded. |
#11
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Hum from the transformer in power supply
"Richard Crowley" wrote in message ... Richard Crowley wrote: Bells are put on transformers to hold in the eddy currents and to shield surrounding circuitry from the influence of eddy currents. "Gib Bogle" wrote ... Why do you say that? I DIDN'T say that. (Note the triple ) "Geoff Wood" said it. I DISPUTED that and the "Geoff Wood" hasn't responded. I most certain did not spout the 'eddy currents' crap. geoff |
#12
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Hum from the transformer in power supply
"Geoff Wood" wrote
I most certain did not spout the 'eddy currents' crap. Apoligies, Mr. Wood did NOT say that. It was the OP, "wantnohum2" who apparently now knows better. |
#13
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Hum from the transformer in power supply
Richard Crowley wrote:
"Geoff Wood" wrote I most certain did not spout the 'eddy currents' crap. Apoligies, Mr. Wood did NOT say that. It was the OP, "wantnohum2" who apparently now knows better. NOW you get it. Gib |
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