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#1
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XMFR phasing question
I've got a PP output transformer that has a center tap but no ultralinear
taps, and two secondaries. Is it possible to determine the correct phasing of the primary relative to the secondary from the wire colors? The secondary taps are known: Yellow: 16 ohms Blue: 8 ohms Black: Ground The Primary colors a Yellow Orange: B+ / center tap Blue Would it be likely that the Yellow wire of the primary is the "high" side, and the blue wire the "low"? Thanks in advance, Jon |
#2
Posted to rec.audio.tubes
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XMFR phasing question
On Wed, 27 May 2009 01:11:01 -0400, Jon Yaeger
wrote: I've got a PP output transformer that has a center tap but no ultralinear taps, and two secondaries. Is it possible to determine the correct phasing of the primary relative to the secondary from the wire colors? The secondary taps are known: Yellow: 16 ohms Blue: 8 ohms Black: Ground The Primary colors a Yellow Orange: B+ / center tap Blue Would it be likely that the Yellow wire of the primary is the "high" side, and the blue wire the "low"? Thanks in advance, Jon Possibly. The only way you are going to find out for sure is to put a signal (doesn't need to be high power - straight off a signal generator will do) into the yellow and blue primary, then see which way round you need to connect the secondary to match the phase. Is there a particular reason why you need to know? Like perhaps if you intend to take some feedback from the speaker side of the transformer? d |
#3
Posted to rec.audio.tubes
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XMFR phasing question
Jon Yaeger wrote: I've got a PP output transformer that has a center tap but no ultralinear taps, and two secondaries. Is it possible to determine the correct phasing of the primary relative to the secondary from the wire colors? The secondary taps are known: Yellow: 16 ohms Blue: 8 ohms Black: Ground The Primary colors a Yellow Orange: B+ / center tap Blue Would it be likely that the Yellow wire of the primary is the "high" side, and the blue wire the "low"? Thanks in advance, Jon Probably you are right, but don't assume anything. So test the OPT in an amp and with sec black to 0V, sec yellow to live out. Then with global FB connected the amp will either oscillate with the wrong tranny phase for stability, or your level will drop due to FB application and it will be stable with a resistance load. You can reverse the anode leads to suit the wanted FB stability and gain reduction. Patrick Turner. ythe y |
#4
Posted to rec.audio.tubes
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XMFR phasing question
Don Pearce wrote:
On Wed, 27 May 2009 01:11:01 -0400, Jon Yaeger wrote: I've got a PP output transformer that has a center tap but no ultralinear taps, and two secondaries. Is it possible to determine the correct phasing of the primary relative to the secondary from the wire colors? The secondary taps are known: Yellow: 16 ohms Blue: 8 ohms Black: Ground The Primary colors a Yellow Orange: B+ / center tap Blue Would it be likely that the Yellow wire of the primary is the "high" side, and the blue wire the "low"? Thanks in advance, Jon Possibly. The only way you are going to find out for sure is to put a signal (doesn't need to be high power - straight off a signal generator will do) into the yellow and blue primary, then see which way round you need to connect the secondary to match the phase. Is there a particular reason why you need to know? Like perhaps if you intend to take some feedback from the speaker side of the transformer? d Use a positive-going pulse, 10% on, 90% off, around 1 KHz. Very easy to observe phase on the output with this kind of input. If your sig generator is rated for a 600-ohm load, this'll work fine. LV |
#6
Posted to rec.audio.tubes
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XMFR phasing question
in article , Lord Valve at
wrote on 5/27/09 9:46 AM: Don Pearce wrote: On Wed, 27 May 2009 01:11:01 -0400, Jon Yaeger wrote: I've got a PP output transformer that has a center tap but no ultralinear taps, and two secondaries. Is it possible to determine the correct phasing of the primary relative to the secondary from the wire colors? The secondary taps are known: Yellow: 16 ohms Blue: 8 ohms Black: Ground The Primary colors a Yellow Orange: B+ / center tap Blue Would it be likely that the Yellow wire of the primary is the "high" side, and the blue wire the "low"? Thanks in advance, Jon Possibly. The only way you are going to find out for sure is to put a signal (doesn't need to be high power - straight off a signal generator will do) into the yellow and blue primary, then see which way round you need to connect the secondary to match the phase. Is there a particular reason why you need to know? Like perhaps if you intend to take some feedback from the speaker side of the transformer? d Use a positive-going pulse, 10% on, 90% off, around 1 KHz. Very easy to observe phase on the output with this kind of input. If your sig generator is rated for a 600-ohm load, this'll work fine. LV LV, Thanks for your suggestion. Last night (before I wrote the post) I tried the square wave function using a Heath signal generator, but it really wasn't up to the task. It did not generate useful positive-going pulses, and one channel of my Tek 60 Mhz. scope isn't up to par, so I gave up. I guess it's time for an equipment upgrade . . . I appreciate your help. Jon |
#7
Posted to rec.audio.tubes
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XMFR phasing question - answered
"Jon Yaeger" wrote in message ... I've got a PP output transformer that has a center tap but no ultralinear taps, and two secondaries. Is it possible to determine the correct phasing of the primary relative to the secondary from the wire colors? The secondary taps are known: Yellow: 16 ohms Blue: 8 ohms Black: Ground The Primary colors a Yellow Orange: B+ / center tap Blue Would it be likely that the Yellow wire of the primary is the "high" side, and the blue wire the "low"? Thanks in advance, Jon In the absence of having a dual-chnl scope... Use two balanced (preferably) inputs of a sound mixer, Connect sig gen giving around 0.5V @ 800Hz and the xfrmr primary [CT and one of the push-pulls] into first chnl at -Line- level, and arrange for any sec (one at a time) to feed into next input at -Mic- level. Then pre-adjust each chnl gain pot, but solo, to give -6dB. Now open both pots: if the inputs sum, they are in phase and will give 0dB at mixer; but, if cancelling and ergo out of phase, invert the sec's wires. Make a note of the 'hot' colours of each set. End of guesswork! Jim use this wheeze for analysing phase of any unmarked audio transformer, if around 10:1 to 1:1, set both chnl sensitivities to Line. Jim |
#8
Posted to rec.audio.tubes
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XMFR phasing question
On May 27, 10:07*pm, Jon Yaeger wrote:
in article , Lord Valve at wrote on 5/27/09 9:46 AM: Don Pearce wrote: On Wed, 27 May 2009 01:11:01 -0400, Jon Yaeger wrote: I've got a PP output transformer that has a center tap but no ultralinear taps, and two secondaries. Is it possible to determine the correct phasing of the primary relative to the secondary from the wire colors? The secondary taps are known: Yellow: * 16 ohms Blue: * * *8 ohms Black: * * Ground The Primary colors a Yellow Orange: * B+ / center tap Blue Would it be likely that the Yellow wire of the primary is the "high" side, and the blue wire the "low"? Thanks in advance, Jon Possibly. The only way you are going to find out for sure is to put a signal (doesn't need to be high power - straight off a signal generator will do) into the yellow and blue primary, then see which way round you need to connect the secondary to match the phase. Is there a particular reason why you need to know? Like perhaps if you intend to take some feedback from the speaker side of the transformer? d Use a positive-going pulse, 10% on, 90% off, around 1 KHz. Very easy to observe phase on the output with this kind of input. *If your sig generator is rated for a 600-ohm load, this'll work fine. Thanks for your suggestion. Last night (before I wrote the post) I tried the square wave function using a Heath signal generator, but it really wasn't up to the task. *It did not generate useful positive-going pulses, and one channel of my Tek 60 Mhz. scope isn't up to par, so I gave up. I guess it's time for an equipment upgrade *. . . Without a fully and correctly working 2 channel scope I would simply not work on anything, but that's because I am spoiled. Scopes are not expensive. THAT SAID you can do this whole job with nothing but a sine wave generator, limited for safe voltage and current, and a voltmeter. You first determine what the groups of wires are as far as their respective windings and where they are on the winding and then you series them together and see if they series-boost or series-buck. This whole procedure is called "phasing out". |
#9
Posted to rec.audio.tubes
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XMFR phasing question
"Jon Yaeger" wrote in message ... I've got a PP output transformer that has a center tap but no ultralinear taps, and two secondaries. Is it possible to determine the correct phasing of the primary relative to the secondary from the wire colors? The secondary taps are known: Yellow: 16 ohms Blue: 8 ohms Black: Ground The Primary colors a Yellow Orange: B+ / center tap Blue Would it be likely that the Yellow wire of the primary is the "high" side, and the blue wire the "low"? Thanks in advance, Jon i wrote a useful reply XMFR phasing question - answered yesterday but it has not yet been published by newsgroup's scrutineer. sincerely Jim |
#10
Posted to rec.audio.tubes
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XMFR phasing question
Jon Yaeger wrote: in article , Patrick Turner at wrote on 5/27/09 6:25 AM: Jon Yaeger wrote: I've got a PP output transformer that has a center tap but no ultralinear taps, and two secondaries. Is it possible to determine the correct phasing of the primary relative to the secondary from the wire colors? The secondary taps are known: Yellow: 16 ohms Blue: 8 ohms Black: Ground The Primary colors a Yellow Orange: B+ / center tap Blue Would it be likely that the Yellow wire of the primary is the "high" side, and the blue wire the "low"? Thanks in advance, Jon Probably you are right, but don't assume anything. So test the OPT in an amp and with sec black to 0V, sec yellow to live out. Then with global FB connected the amp will either oscillate with the wrong tranny phase for stability, or your level will drop due to FB application and it will be stable with a resistance load. You can reverse the anode leads to suit the wanted FB stability and gain reduction. Patrick Turner. ythe y * * * I thought that method would be fool-proof, but being a bit lazy I was hoping for something simpler. Thanks for your help!! Jon There is something simpler than trying the OPT out in an amp. But I thought perhaps you'd have an amp to try the OPT. The simpler method is as foillows. Connect a sig gene with low Rout (say 1k ohm or less, 600 ohms etc ) with 0V connected to the CT, ) orange wire, and active lead to the yellow end of the P winding. Set the sig gene for say 3.0Vrms at 500Hz. You should be able to measure 0V to the other blue end of the P to give 3.0Vrms or 6Vrms across the whole P, blue to yellow. Now connect the black Sec end also to the CT+0V. Measure the voltage between 0V and yellow S end, 16 ohms and 0V, and record the voltage. Do the same between 0V and the blue sec and record the voltage. Now measure the voltage between the yellow Sec and the yellow Pri. If it is less than 3.0Vrms, then the voltages are in phase, if it is more than 3.0Vrms, it is oppositely phased. Suppose the OPT was 20:1 TR, then with 6V across the whole P you's have +3V and -3V at each end measured from 0V. Assume the yellow is +3V, and blue is -3V, because your signal generator is connected to between CT and yellow. You would have 6/20 = 0.3V between 0V and the 16 ohm yellow tap. But is it +0.3V, or -0.3V? If you measure between the 16 ohm tap and the sig gene/yellow P at +3V, then you will either get 3V -0.3V, or 3V +0.3V, which means 2.7V is same phase, and 3.3V is opposite phase, savvy? The measurements I have asked you to take and record will give you the vital info about the TR and hence the ZR, and exactly what impedance matches are available. Make a label and glue it to the OPT with phase info so that in 5 years when you have forgotten all about what I said, you'll still have the info. Patrick Turner. |
#11
Posted to rec.audio.tubes
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XMFR phasing question
Jon Yaeger wrote: in article , Lord Valve at wrote on 5/27/09 9:46 AM: Don Pearce wrote: On Wed, 27 May 2009 01:11:01 -0400, Jon Yaeger wrote: I've got a PP output transformer that has a center tap but no ultralinear taps, and two secondaries. Is it possible to determine the correct phasing of the primary relative to the secondary from the wire colors? The secondary taps are known: Yellow: 16 ohms Blue: 8 ohms Black: Ground The Primary colors a Yellow Orange: B+ / center tap Blue Would it be likely that the Yellow wire of the primary is the "high" side, and the blue wire the "low"? Thanks in advance, Jon Possibly. The only way you are going to find out for sure is to put a signal (doesn't need to be high power - straight off a signal generator will do) into the yellow and blue primary, then see which way round you need to connect the secondary to match the phase. Is there a particular reason why you need to know? Like perhaps if you intend to take some feedback from the speaker side of the transformer? d Use a positive-going pulse, 10% on, 90% off, around 1 KHz. Very easy to observe phase on the output with this kind of input. If your sig generator is rated for a 600-ohm load, this'll work fine. LV LV, Thanks for your suggestion. Last night (before I wrote the post) I tried the square wave function using a Heath signal generator, but it really wasn't up to the task. It did not generate useful positive-going pulses, and one channel of my Tek 60 Mhz. scope isn't up to par, so I gave up. I guess it's time for an equipment upgrade . . . I appreciate your help. Any audio amatateur can work it all out with nothing more than a volt meter and a low Z signal source. I've assumed you'd have a low Rout sig gene but a heater supply 6.3Vrms at 60Hz will do fine. CAUTION AND WARNING... Always use the low voltage testing signal connected to the ***high voltage** winding which is usually the high dc resistance winding. If you have a 20:1 OPT, and you have 6.3V across the sec, then you have 126Vrms across the P. But say you had a 40:1 OPT, then the P voltage would be 252V and quite deadly!!!!! If you have trouble measuring the dc resistance of a P winding of an OPT with a DMM, it is because of the inductance, so while measuring dc resistance, connect a temporary shorting lead across the sec, and it shorts the inductance that fools the DMM. Any cheap DMM costing $20 should be OK to use, and most read down to mV fairly accurately, ie, within 5% for anything you will read in this case. Patrick Turner. Jon |
#12
Posted to rec.audio.tubes
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XMFR phasing question
On Fri, 29 May 2009 12:34:46 GMT, Patrick Turner
wrote: Jon Yaeger wrote: in article , Lord Valve at wrote on 5/27/09 9:46 AM: Don Pearce wrote: On Wed, 27 May 2009 01:11:01 -0400, Jon Yaeger wrote: I've got a PP output transformer that has a center tap but no ultralinear taps, and two secondaries. Is it possible to determine the correct phasing of the primary relative to the secondary from the wire colors? The secondary taps are known: Yellow: 16 ohms Blue: 8 ohms Black: Ground The Primary colors a Yellow Orange: B+ / center tap Blue Would it be likely that the Yellow wire of the primary is the "high" side, and the blue wire the "low"? Thanks in advance, Jon Possibly. The only way you are going to find out for sure is to put a signal (doesn't need to be high power - straight off a signal generator will do) into the yellow and blue primary, then see which way round you need to connect the secondary to match the phase. Is there a particular reason why you need to know? Like perhaps if you intend to take some feedback from the speaker side of the transformer? d Use a positive-going pulse, 10% on, 90% off, around 1 KHz. Very easy to observe phase on the output with this kind of input. If your sig generator is rated for a 600-ohm load, this'll work fine. LV LV, Thanks for your suggestion. Last night (before I wrote the post) I tried the square wave function using a Heath signal generator, but it really wasn't up to the task. It did not generate useful positive-going pulses, and one channel of my Tek 60 Mhz. scope isn't up to par, so I gave up. I guess it's time for an equipment upgrade . . . I appreciate your help. Any audio amatateur can work it all out with nothing more than a volt meter and a low Z signal source. I've assumed you'd have a low Rout sig gene but a heater supply 6.3Vrms at 60Hz will do fine. CAUTION AND WARNING... Always use the low voltage testing signal connected to the ***high voltage** winding which is usually the high dc resistance winding. If you have a 20:1 OPT, and you have 6.3V across the sec, then you have 126Vrms across the P. But say you had a 40:1 OPT, then the P voltage would be 252V and quite deadly!!!!! If you have trouble measuring the dc resistance of a P winding of an OPT with a DMM, it is because of the inductance, so while measuring dc resistance, connect a temporary shorting lead across the sec, and it shorts the inductance that fools the DMM. Any cheap DMM costing $20 should be OK to use, and most read down to mV fairly accurately, ie, within 5% for anything you will read in this case. Patrick Turner. How does that help in determining the phase? d |
#13
Posted to rec.audio.tubes
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XMFR phasing question
Don Pearce wrote: On Fri, 29 May 2009 12:34:46 GMT, Patrick Turner wrote: Jon Yaeger wrote: in article , Lord Valve at wrote on 5/27/09 9:46 AM: Don Pearce wrote: On Wed, 27 May 2009 01:11:01 -0400, Jon Yaeger wrote: I've got a PP output transformer that has a center tap but no ultralinear taps, and two secondaries. Is it possible to determine the correct phasing of the primary relative to the secondary from the wire colors? The secondary taps are known: Yellow: 16 ohms Blue: 8 ohms Black: Ground The Primary colors a Yellow Orange: B+ / center tap Blue Would it be likely that the Yellow wire of the primary is the "high" side, and the blue wire the "low"? Thanks in advance, Jon Possibly. The only way you are going to find out for sure is to put a signal (doesn't need to be high power - straight off a signal generator will do) into the yellow and blue primary, then see which way round you need to connect the secondary to match the phase. Is there a particular reason why you need to know? Like perhaps if you intend to take some feedback from the speaker side of the transformer? d Use a positive-going pulse, 10% on, 90% off, around 1 KHz. Very easy to observe phase on the output with this kind of input. If your sig generator is rated for a 600-ohm load, this'll work fine. LV LV, Thanks for your suggestion. Last night (before I wrote the post) I tried the square wave function using a Heath signal generator, but it really wasn't up to the task. It did not generate useful positive-going pulses, and one channel of my Tek 60 Mhz. scope isn't up to par, so I gave up. I guess it's time for an equipment upgrade . . . I appreciate your help. Any audio amatateur can work it all out with nothing more than a volt meter and a low Z signal source. I've assumed you'd have a low Rout sig gene but a heater supply 6.3Vrms at 60Hz will do fine. CAUTION AND WARNING... Always use the low voltage testing signal connected to the ***high voltage** winding which is usually the high dc resistance winding. If you have a 20:1 OPT, and you have 6.3V across the sec, then you have 126Vrms across the P. But say you had a 40:1 OPT, then the P voltage would be 252V and quite deadly!!!!! If you have trouble measuring the dc resistance of a P winding of an OPT with a DMM, it is because of the inductance, so while measuring dc resistance, connect a temporary shorting lead across the sec, and it shorts the inductance that fools the DMM. Any cheap DMM costing $20 should be OK to use, and most read down to mV fairly accurately, ie, within 5% for anything you will read in this case. Patrick Turner. How does that help in determining the phase? If you had been following all the things I have said on the matter, you'd have understood. I don't like to see people getting an electric shock because they were cavalier with voltage measurements. Some ppl might assume a winding is the primary when it wasn't, then connect 110V and for a second there's a big hum and huge voltage on some other winding. Patrick Turner. d |
#14
Posted to rec.audio.tubes
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XMFR phasing question
On Sat, 30 May 2009 14:10:33 GMT, Patrick Turner
wrote: How does that help in determining the phase? If you had been following all the things I have said on the matter, you'd have understood. I don't like to see people getting an electric shock because they were cavalier with voltage measurements. Some ppl might assume a winding is the primary when it wasn't, then connect 110V and for a second there's a big hum and huge voltage on some other winding. I've no idea how that answers my question. d |
#15
Posted to rec.audio.tubes
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XMFR phasing question
jim greg wrote: "Jon Yaeger" wrote in message ... I've got a PP output transformer that has a center tap but no ultralinear taps, and two secondaries. Is it possible to determine the correct phasing of the primary relative to the secondary from the wire colors? The secondary taps are known: Yellow: 16 ohms Blue: 8 ohms Black: Ground The Primary colors a Yellow Orange: B+ / center tap Blue Would it be likely that the Yellow wire of the primary is the "high" side, and the blue wire the "low"? Thanks in advance, Jon i wrote a useful reply XMFR phasing question - answered yesterday but it has not yet been published by newsgroup's scrutineer. sincerely Jim As far as I am aware, this group don't have no scrootineer, or moderator man. It be possible fo any one to type whatever an it jus gets posted up. Otherwise it'd be kinda quiet around here. So if there was a delay after posting off your post, then maybe its in the ISP server or the route you have. In the past 9 years since i been here there have been a number of ISPs I was with who could not give me a reliable path to r.a.t. They could always do alt.binaries.blondes, but could not provide links to many other groups. Patrick Turner. |
#16
Posted to rec.audio.tubes
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XMFR phasing question
"Patrick Turner" wrote in message ... jim greg wrote: "Jon Yaeger" wrote in message ... I've got a PP output transformer that has a center tap but no ultralinear taps, and two secondaries. Is it possible to determine the correct phasing of the primary relative to the secondary from the wire colors? The secondary taps are known: Yellow: 16 ohms Blue: 8 ohms Black: Ground The Primary colors a Yellow Orange: B+ / center tap Blue Would it be likely that the Yellow wire of the primary is the "high" side, and the blue wire the "low"? Thanks in advance, Jon i wrote a useful reply XMFR phasing question - answered yesterday but it has not yet been published by newsgroup's scrutineer. sincerely Jim As far as I am aware, this group don't have no scrootineer, or moderator man. It be possible fo any one to type whatever an it jus gets posted up. Otherwise it'd be kinda quiet around here. So if there was a delay after posting off your post, then maybe its in the ISP server or the route you have. In the past 9 years since i been here there have been a number of ISPs I was with who could not give me a reliable path to r.a.t. They could always do alt.binaries.blondes, but could not provide links to many other groups. Patrick Turner. so nowadays i can read off RAT but not write to the NG. sounds like there is unwelcoming bias afoot. often used to add to threads in the past. anyway i am now corresponding with Jon Yaeger directly. a pity i can't send my writings to NG. Jim |
#17
Posted to rec.audio.tubes
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XMFR phasing question
On Sat, 30 May 2009 21:08:32 +0100, "jim greg"
wrote: "Patrick Turner" wrote in message ... jim greg wrote: "Jon Yaeger" wrote in message ... I've got a PP output transformer that has a center tap but no ultralinear taps, and two secondaries. Is it possible to determine the correct phasing of the primary relative to the secondary from the wire colors? The secondary taps are known: Yellow: 16 ohms Blue: 8 ohms Black: Ground The Primary colors a Yellow Orange: B+ / center tap Blue Would it be likely that the Yellow wire of the primary is the "high" side, and the blue wire the "low"? Thanks in advance, Jon i wrote a useful reply XMFR phasing question - answered yesterday but it has not yet been published by newsgroup's scrutineer. sincerely Jim As far as I am aware, this group don't have no scrootineer, or moderator man. It be possible fo any one to type whatever an it jus gets posted up. Otherwise it'd be kinda quiet around here. So if there was a delay after posting off your post, then maybe its in the ISP server or the route you have. In the past 9 years since i been here there have been a number of ISPs I was with who could not give me a reliable path to r.a.t. They could always do alt.binaries.blondes, but could not provide links to many other groups. Patrick Turner. so nowadays i can read off RAT but not write to the NG. sounds like there is unwelcoming bias afoot. often used to add to threads in the past. anyway i am now corresponding with Jon Yaeger directly. a pity i can't send my writings to NG. Jim USENET is not moderated for the most part. The problem almost surely has to be with your computer/news reader or ISP..unless you have a court order not to post or something .. |
#18
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XMFR phasing question
On May 30, 9:10*am, Patrick Turner wrote:
Don Pearce wrote: On Fri, 29 May 2009 12:34:46 GMT, Patrick Turner wrote: Jon Yaeger wrote: in article , Lord Valve at wrote on 5/27/09 9:46 AM: Don Pearce wrote: On Wed, 27 May 2009 01:11:01 -0400, Jon Yaeger wrote: I've got a PP output transformer that has a center tap but no ultralinear taps, and two secondaries. Is it possible to determine the correct phasing of the primary relative to the secondary from the wire colors? The secondary taps are known: Yellow: * 16 ohms Blue: * * *8 ohms Black: * * Ground The Primary colors a Yellow Orange: * B+ / center tap Blue Would it be likely that the Yellow wire of the primary is the "high" side, and the blue wire the "low"? Thanks in advance, Jon Possibly. The only way you are going to find out for sure is to put a signal (doesn't need to be high power - straight off a signal generator will do) into the yellow and blue primary, then see which way round you need to connect the secondary to match the phase. Is there a particular reason why you need to know? Like perhaps if you intend to take some feedback from the speaker side of the transformer? d Use a positive-going pulse, 10% on, 90% off, around 1 KHz. Very easy to observe phase on the output with this kind of input. *If your sig generator is rated for a 600-ohm load, this'll work fine. LV LV, Thanks for your suggestion. Last night (before I wrote the post) I tried the square wave function using a Heath signal generator, but it really wasn't up to the task. *It did not generate useful positive-going pulses, and one channel of my Tek 60 Mhz. scope isn't up to par, so I gave up. I guess it's time for an equipment upgrade *. . . I appreciate your help. Any audio amatateur can work it all out with nothing more than a volt meter and a low Z signal source. I've assumed you'd have a low Rout sig gene but a heater supply 6.3Vrms at 60Hz will do fine. CAUTION AND WARNING... Always use the low voltage testing signal connected to the ***high voltage** winding which is usually the high dc resistance winding. If you have a 20:1 OPT, and you have 6.3V across the sec, then you have 126Vrms across the P. But say you had a 40:1 OPT, then the P voltage would be 252V and quite deadly!!!!! If you have trouble measuring the dc resistance of a P winding of an OPT with a DMM, it is because of the inductance, so while measuring dc resistance, connect a temporary shorting lead across the sec, and it shorts the inductance that fools the DMM. Any cheap DMM costing $20 should be OK to use, and most read down to mV fairly accurately, ie, within 5% for anything you will read in this case. Patrick Turner. How does that help in determining the phase? If you had been following all the things I have said on the matter, you'd have understood. I don't like to see people getting an electric shock because they were cavalier with voltage measurements. Some ppl might assume a winding is the primary when it wasn't, then connect 110V and for a second there's a big hum and huge voltage on some other winding. Patrick Turner. d They should always use a current limited source for testing and work with one hand. Get a piece of dry lumber and some tacks and solder the wires to tacks for easy test if flying leads are what you have. Make up a test cable with some grabbers on the ends so you can work one handed easily with a scope probe. I'd wear a rubber glove as well in HV situations. I keep pushing everyone to get a HP 200CD for this work and lots else. Unlike solid state units you can't hardly blow them up. Using a lightbulb and a step down xfmr off a variac works too, but the lunchbox is inherently safer-there is just not that much energy available and you can work at 400 or 1000 hz instead of 60 or 50. There is no UK or Euro equivalent to the 200CD or 200AB-get the real thing. Later ones have multi standard power supplies. For earlier ones, 2:1 transformers are cheap in the UK because they used 110V drills for construction by law for years. |
#19
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XMFR phasing question
Always use the low voltage testing signal connected to the ***high voltage** winding which is usually the high dc resistance winding. If you have a 20:1 OPT, and you have 6.3V across the sec, then you have 126Vrms across the P. But say you had a 40:1 OPT, then the P voltage would be 252V and quite deadly!!!!! If you have trouble measuring the dc resistance of a P winding of an OPT with a DMM, it is because of the inductance, so while measuring dc resistance, connect a temporary shorting lead across the sec, and it shorts the inductance that fools the DMM. Any cheap DMM costing $20 should be OK to use, and most read down to mV fairly accurately, ie, within 5% for anything you will read in this case. Patrick Turner. How does that help in determining the phase? We need to understand the concept of the transformer here. When we say "series boosting" and "series bucking" in terms of the voltage, do you understand this issue? We have a transformer with two separate windings. We call the four terminals or wires, A,B, C, and D. A and B are one winding , C and D the other. We put an AC voltage on one, and get another separate voltage on the other. Now if we put the windings in series, hooking C to B, leaving the source on A nad B. and measure the voltage vrom A to D. Is the voltage on A-D HIGHER or LOWER than on A-B? If it is higher, they are series boosting. If it is lower they are series bucking. Many good books on transformers exist. Read them, but also get some real ones and play with them. |
#20
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XMFR phasing question
Last night (before I wrote the post) I tried the square wave function using a Heath signal generator, but it really wasn't up to the task. It did not generate useful positive-going pulses, and one channel of my Tek 60 Mhz. scope isn't up to par, so I gave up. IOW someone gave it to you because one channel is dead and no one will fix it for free. |
#21
Posted to rec.audio.tubes
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XMFR phasing question
Bret L wrote: Always use the low voltage testing signal connected to the ***high voltage** winding which is usually the high dc resistance winding. If you have a 20:1 OPT, and you have 6.3V across the sec, then you have 126Vrms across the P. But say you had a 40:1 OPT, then the P voltage would be 252V and quite deadly!!!!! If you have trouble measuring the dc resistance of a P winding of an OPT with a DMM, it is because of the inductance, so while measuring dc resistance, connect a temporary shorting lead across the sec, and it shorts the inductance that fools the DMM. Any cheap DMM costing $20 should be OK to use, and most read down to mV fairly accurately, ie, within 5% for anything you will read in this case. Patrick Turner. How does that help in determining the phase? We need to understand the concept of the transformer here. When we say "series boosting" and "series bucking" in terms of the voltage, do you understand this issue? We have a transformer with two separate windings. We call the four terminals or wires, A,B, C, and D. A and B are one winding , C and D the other. We put an AC voltage on one, and get another separate voltage on the other. Now if we put the windings in series, hooking C to B, leaving the source on A nad B. and measure the voltage vrom A to D. Is the voltage on A-D HIGHER or LOWER than on A-B? If it is higher, they are series boosting. If it is lower they are series bucking. Many good books on transformers exist. Read them, but also get some real ones and play with them. My posts on the subject did try to explain that by measuring voltages between relative terminals and by using powers of plain logical thinking, one could soon work out the relative phasing of windings on any Xfrmr. But many cannot think at all.... Patrick Turner. |
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