Greetings Fellow Tweakers,
I have some rather basic transformer questions that I could not answer with an archive search. I hope they will be of general interest.
I'm hoping to buy a versatile transformer, that I can reconfigure to create various output voltages as I experiment with various circuits and tubes. Hence the following questions.
I realize that some of the actions I ask about might cause explosions, sparks, and fire, which is why I am asking rather than doing.
Okay, for this example, please check out this Plitron transformer--my questions will relate to its various terminal numbers. . As one can see, it has two 120VAC primaries, and many secondaries.
Okay...
Okay, first, what is the implication of the dual primaries? Is there any difference between powering both, or just one primary? Could one connect 2 and 3, and apply 120VAC across 1 and four (connect the two primaries in series) to get *half* the specified voltages across the secondaries?
Second: Can I combine secondaries to add their output voltages?
For example, there is 678VAC between 6 and 7, and 342VAC between 8 and 9. Could I connect 7 to 8 to get 1020VAC between 6 and 9, and then rectify that?
Third: If my second proposal would result in sparks and death, could I rectify 6 and 7 alone, and 8 and 9 alone, and then combine their rectified output to get a higher DC voltage (I am a little more confident that this method would work, but would rather not build two separate rectifiers).
Thanks for you insights and tolerance of my cluelessness.
Best,
George Ferguson
I have some rather basic transformer questions that I could not answer with an archive search. I hope they will be of general interest.
I'm hoping to buy a versatile transformer, that I can reconfigure to create various output voltages as I experiment with various circuits and tubes. Hence the following questions.
I realize that some of the actions I ask about might cause explosions, sparks, and fire, which is why I am asking rather than doing.
Okay, for this example, please check out this Plitron transformer--my questions will relate to its various terminal numbers. . As one can see, it has two 120VAC primaries, and many secondaries.
Okay...
Okay, first, what is the implication of the dual primaries? Is there any difference between powering both, or just one primary? Could one connect 2 and 3, and apply 120VAC across 1 and four (connect the two primaries in series) to get *half* the specified voltages across the secondaries?
Second: Can I combine secondaries to add their output voltages?
For example, there is 678VAC between 6 and 7, and 342VAC between 8 and 9. Could I connect 7 to 8 to get 1020VAC between 6 and 9, and then rectify that?
Third: If my second proposal would result in sparks and death, could I rectify 6 and 7 alone, and 8 and 9 alone, and then combine their rectified output to get a higher DC voltage (I am a little more confident that this method would work, but would rather not build two separate rectifiers).
Thanks for you insights and tolerance of my cluelessness.
Best,
George Ferguson
You have to start somewhere Frank. I consider myself a competent valve amp builder (For my personal needs). But I got a post over at Audioasylum that went like this ...
"Someone get me rope"
because I did not understand why in an unloaded psu the voltage did not drop across voltage dropping resistor.
Don't underestimate a person's ability to learn! What have you taught George here?
"Someone get me rope"
because I did not understand why in an unloaded psu the voltage did not drop across voltage dropping resistor.
Don't underestimate a person's ability to learn! What have you taught George here?
Reminds me of my TV 405 line servicing days when I used to <get stung> by the EHT of the line o/p .......inevitable clip of the elbow on the topcap....ch**t
That Plitron tranny rated at 723W 0.65A could sting you hard if you mishandle it....It looks a hard and high way to learn......remember alot of DMM's don't like going above 600VAC.
The good regulation factor of +/-3% for that 700V winding is indictative of no-nonsense power capability....with suitable PIV full bridge rectum + suitable cap you will hit 1KV.....watch it.......
rich
That Plitron tranny rated at 723W 0.65A could sting you hard if you mishandle it....It looks a hard and high way to learn......remember alot of DMM's don't like going above 600VAC.
The good regulation factor of +/-3% for that 700V winding is indictative of no-nonsense power capability....with suitable PIV full bridge rectum + suitable cap you will hit 1KV.....watch it.......
rich
Bas said:
My friends, or the merely generous, will answer my questions in the spirit that I posed them. If not, I will learn the answers elsewhere, and post them here so that others may learn from my ignorance.
By the way, how much voltage won't kill me?
Best,
George "Grasshopper" Ferguson
That's the spirit! Thanks.
Criticizing a neophyte is too easy, so I don't waste my time either doing it or responding in kind. In grad school I was always the guy in the front row, raising my hand to ask the "stupid" question, while the rest of the class sat silent, afraid to look ignorant. Teachers loved me.
My friends, or the merely generous, will answer my questions in the spirit that I posed them. If not, I will learn the answers elsewhere, and post them here so that others may learn from my ignorance.
Thanks Rich and don't worry--no hardware until I know what I'm doing. For the time being, the only stings I'll be getting will be verbal.
By the way, how much voltage won't kill me?
Best,
George "Grasshopper" Ferguson
Connecting Tranformer Primaries or Secondaries in Series
Hey All,
Well, I went ahead and found some answers on my own.
Looking at this transformer primer from Glass Audio (particularly "Modifying Transformers" and Figure 7), it seems my idea about connecting primary or secondary windings in series was correct--doing so effectively changes the windings ratio and the resulting voltage.
Since no one gave me any specific information, I'm guessing the negative and non-reactions were because I picked a high-voltage transformer to use as an example for my questions.
As always, I invite your constructive feedback. Flames will be cheerfully ignored.
Best,
George Ferguson
Hey All,
Well, I went ahead and found some answers on my own.
Looking at this transformer primer from Glass Audio (particularly "Modifying Transformers" and Figure 7), it seems my idea about connecting primary or secondary windings in series was correct--doing so effectively changes the windings ratio and the resulting voltage.
Since no one gave me any specific information, I'm guessing the negative and non-reactions were because I picked a high-voltage transformer to use as an example for my questions.
As always, I invite your constructive feedback. Flames will be cheerfully ignored.
Best,
George Ferguson
George, yes you can series those 2 windings. Now, with that said the top winding is rated for 65mA and the second is rated for 30mA. If you put these two in series then the current rating of the second winding limits the combined series output to 30mA. You could draw more current than that if you want but don't be supprised when winding 2 burns up.
Later
BZ
Later
BZ
Hi Frank,
The point I was trying to make is that I with very little electronics knowledge have built a decent valve amp
Along the way I have been shocked quite a few times and asked some very dumb questions. But then again even qualified/knowledgable folk get shocked.
But you are right...can't harm to keep warning people that it is dangerous playing with high voltage.
Cheers,
Bas
True
The point I was trying to make is that I with very little electronics knowledge have built a decent valve amp
Along the way I have been shocked quite a few times and asked some very dumb questions. But then again even qualified/knowledgable folk get shocked.
But you are right...can't harm to keep warning people that it is dangerous playing with high voltage.
Cheers,
Bas
Grasshopper, people who are being harsh may also be trying to be kind. My best advice to anyone getting started in building tube stuff (or anything involving high voltages) is to find an old guy to (in person) show you the ropes. A ham radio guy over the age of 50 would be a good start. Or a TV repairman of a similar age who remembers what a 1G3 rectifier was, or how to discharge a CRT anode safely. There is no substitute for hands-on instruction- I'm grateful for a bunch of guys who, when I was a kid, taught me patiently how not to fry myself.
Frank said:
Sy said:
You're right, this hobby is dangerous.
But even the wisest and safest builder was a neophyte once, and never would have become wise and safe without help.
Yes, I pursue all avenues of learning--online and off. It would be a pity if my neophyte status prevented me from both receiving and giving help here. If it does, please let me know.
That said, thanks to all for listening and helping, and good luck in all your projects.
And I hope my questions and answers have helped others.
Best,
George Ferguson
Apology accepted.
Actually, I did and do understand that--that's why I was asking questions.
Sy said:
Thanks; I do realize that. At the same time, responding to my request for knowledge with in effect "You are too clueless--go away", is neither pleasant nor helpful. It gives me no answers to my questions, and insults do not discourage me from learning about building tube gear.
You're right, this hobby is dangerous.
But even the wisest and safest builder was a neophyte once, and never would have become wise and safe without help.
Yes, I pursue all avenues of learning--online and off. It would be a pity if my neophyte status prevented me from both receiving and giving help here. If it does, please let me know.
That said, thanks to all for listening and helping, and good luck in all your projects.
And I hope my questions and answers have helped others.
Best,
George Ferguson
Yes everyone's right on this one........alot of present generation people over here get very <uptight > about working with H.V...the fear of getting stung by it and then put off by the hazard.....perhaps us oldies took it in our stride as I did working in armed forces (there was no low voltage in comms other than tube heaters).
Anyone working with me on amp servicing will soon pick the HV cult up....keep at it and watch those Joules.
The old motto ....keep the other hand off the chassis (and in your pocket) while the other pokes around with the B+....and also invest in a bench isolating transformer. This bit of safety has kept me alive.....sofar.
rich
Anyone working with me on amp servicing will soon pick the HV cult up....keep at it and watch those Joules.
The old motto ....keep the other hand off the chassis (and in your pocket) while the other pokes around with the B+....and also invest in a bench isolating transformer. This bit of safety has kept me alive.....sofar.
rich
Hey Rich, 
Many thanks for the encouragement and advice.
One of the ironies in all this is that I am aware of the danger, and the importance of seeking and following advice. I've learned to fly my own ultralight--a similarly dangerous and unregulated sport, with its fair share of cocky idiots, sure that they are right to ignore safe practices right up until the moment they come to a nasty end.
"A wise man learns from others' mistakes, a fool can't learn from his own." I try to be in the first category, which does not mean that I will not mess up. But each safe practice is a safety net that might save me from myself.
Anyway, I'd like to ask more questions about safe(r) practices and share what I think I know, but I want to be respectful of this forum and its moderators. So although I think others might benefit from such talk, I'll take it offline if the moderators are uncomfortable with such talk, either personally or legally. So moderators, please let me know if you want me to take it private.
Happy Tweaking,
George Ferguson
Many thanks for the encouragement and advice.
One of the ironies in all this is that I am aware of the danger, and the importance of seeking and following advice. I've learned to fly my own ultralight--a similarly dangerous and unregulated sport, with its fair share of cocky idiots, sure that they are right to ignore safe practices right up until the moment they come to a nasty end.
"A wise man learns from others' mistakes, a fool can't learn from his own." I try to be in the first category, which does not mean that I will not mess up. But each safe practice is a safety net that might save me from myself.
Anyway, I'd like to ask more questions about safe(r) practices and share what I think I know, but I want to be respectful of this forum and its moderators. So although I think others might benefit from such talk, I'll take it offline if the moderators are uncomfortable with such talk, either personally or legally. So moderators, please let me know if you want me to take it private.
Happy Tweaking,
George Ferguson
Yes, I've always maintained....safety an itchy business....for the benefit for others perhaps not so fortunate of how to go about power engineering ....safety is something we inherently pick up as we go along....either learn it at tech school but alot of us work alone on the home bench .....we don't have deadman's pedals..... as train drivers do. Living in a wooden house, my greatest fear is fire...detaching the workplace plug from the wall socket is a good insurance policy.........a lost soldering iron tip is like a dog-end.
I also drive & fire steam railway (full size), the dB and clanker is just as loud as HiFi and just as hazardous.. ..Both sound merciful and glorious to the ears when really wound up......
Viva to all this Tube and steam Heritage stuff.........it's brilliant!!
rich
I also drive & fire steam railway (full size), the dB and clanker is just as loud as HiFi and just as hazardous.. ..Both sound merciful and glorious to the ears when really wound up......
Viva to all this Tube and steam Heritage stuff.........it's brilliant!!
rich
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