Anyone here can help me find a design of output transformer that will be used for SET amp (2A3 tube amp). Basically primary impedance is 2.5K and Secondary would be 4, 8, 16 Ohm.
design? you want to wind your own?
if not, and you like one that is already well made, talk to john poscablo. he has very good C-core OPTs. you can also ask him for his amorphous version.
if not, and you like one that is already well made, talk to john poscablo. he has very good C-core OPTs. you can also ask him for his amorphous version.
joan2,
thanks, just wait for your post.
ArnoldC,
i have friend that has knowledge of doing the xformer and he is asking me for the data needed prior to winding the xformer.
Thanks guys....🙂 🙂 🙂
thanks, just wait for your post.
ArnoldC,
i have friend that has knowledge of doing the xformer and he is asking me for the data needed prior to winding the xformer.
Thanks guys....🙂 🙂 🙂
ok here is one design for output traffo you specified:
1. core is ei 1 1/4 , available from deeco, you will need about 3kgs for set of two outputs..
2. a standard plastic bobbin for 1 1/4 sqaure core stack is used, this is available from deeco...
3. primary winding will have 5000 turns awg 32 heavy formex split in two sections of 2500 turns each, primary will have estimated dc resistance of about 230 ohms...
4. secondary will have 400 turns awg 22 enamel wire for 16 ohms, 200 turns for 4ohms and 280 turns for 8ohms, if you like, you can also split this into two coils, so that primary and secondary will interleave... the secondary winding will have estimated dc resistance of about 2.2 ohms...
5. adequate insulations must be used between primary and secondary coils....
6. once the completed traffo is wired up and finished, you can install the ei cores, all the e's go together and there must be a gap between the e and the i to prevent dc saturation, you can use fish paper as a gapping material.
7. completed traffo with brackets installed can be dipped in polyurethane insulating varnish, you can use the air drying type if you do not have oven for this job.
8. if you want to find out the primary inductance, you can use a capacitor of 1ufd in series with the primary coil, and feed a 50volt 60hz voltage taking measurements for voltage, you can determine inductance, bearing in mind that in a series ckt current flowing thru the cap is the same as that on the coils....
cost of materials be around 600pesos, i do not know how much your winder will charge you, please feedback me...
should youu have further questions, you can e mail me at tonytecson@yahoo.com
1. core is ei 1 1/4 , available from deeco, you will need about 3kgs for set of two outputs..
2. a standard plastic bobbin for 1 1/4 sqaure core stack is used, this is available from deeco...
3. primary winding will have 5000 turns awg 32 heavy formex split in two sections of 2500 turns each, primary will have estimated dc resistance of about 230 ohms...
4. secondary will have 400 turns awg 22 enamel wire for 16 ohms, 200 turns for 4ohms and 280 turns for 8ohms, if you like, you can also split this into two coils, so that primary and secondary will interleave... the secondary winding will have estimated dc resistance of about 2.2 ohms...
5. adequate insulations must be used between primary and secondary coils....
6. once the completed traffo is wired up and finished, you can install the ei cores, all the e's go together and there must be a gap between the e and the i to prevent dc saturation, you can use fish paper as a gapping material.
7. completed traffo with brackets installed can be dipped in polyurethane insulating varnish, you can use the air drying type if you do not have oven for this job.
8. if you want to find out the primary inductance, you can use a capacitor of 1ufd in series with the primary coil, and feed a 50volt 60hz voltage taking measurements for voltage, you can determine inductance, bearing in mind that in a series ckt current flowing thru the cap is the same as that on the coils....
cost of materials be around 600pesos, i do not know how much your winder will charge you, please feedback me...
should youu have further questions, you can e mail me at tonytecson@yahoo.com
hi,
you can try 'podmon' in legarda, 734-67-26, they have been in bussiness of transformer rewinding since after ww2, contact person is nelia....
while you are at it, i can design a filter choke and power traffo for you, just email me....
tony
you can try 'podmon' in legarda, 734-67-26, they have been in bussiness of transformer rewinding since after ww2, contact person is nelia....
while you are at it, i can design a filter choke and power traffo for you, just email me....
tony
I would like to wind a se trans. At the moment, my trans winder is doing power trans. Some how the bandwidth is 50-25Khz, for a 20va trans. The primary winding inductance is 4H. I measure a cheap audio trans se has a inductance of 8H therefore i would need to ask him to modify his power winding methods to do me an audiotrans i.e. gapping the EI. I wondering on your design, how much would the inductance be? How do you wind the primaries? From your post
1 and 2 looks like a 20va trans
3. primary winding will have 5000 turns awg 32 heavy formex split in two sections of 2500 turns each, primary will have estimated dc resistance of about 230 ohms... How is this wound? With 2 split primaries of
]|
first primary(2500 turns) ]|
]|
second primary(2500 turns) ]|
]
]=winding
| Core
Is this done in this way? IF so what are the benefits of having two primaries? Would it be better to split up the primaries into more segments i.e. 5 segments of 1000 turns
4. secondary will have 400 turns awg 22 enamel wire for 16 ohms, 200 turns for 4ohms and 280 turns for 8ohms, if you like, you can also split this into two coils, so that primary and secondary will interleave... What do you mean by split this into two coils so that primary and secondary will interleave. Could you show a sketch on how it is done
6. once the completed traffo is wired up and finished, you can install the ei cores, all the e's go together and there must be a gap between the e and the i to prevent dc saturation, you can use fish paper as a gapping material. Other than fish paper, is there a way to calculate how much gapping is needed for different dc currents allowable. How much microns is fish paper?
8. if you want to find out the primary inductance, you can use a capacitor of 1ufd in series with the primary coil, and feed a 50volt 60hz voltage taking measurements for voltage, you can determine inductance, bearing in mind that in a series ckt current flowing thru the cap is the same as that on the coils....
Is this how is done
50 volts 60hz signal-------|(1uf)|-----------primaries. The voltmeter measures the voltage across the primary windings? Does the end of the primary connect to any ware, i.e. ground? To determine inductance, the voltage of 50volts –(The reading from multimeter across the winding)/(current following thru the coils ) =XL. With XL =2*pi*f*L. L is found as f is frequency. Is my calculations correct
Thanks for the help
1 and 2 looks like a 20va trans
3. primary winding will have 5000 turns awg 32 heavy formex split in two sections of 2500 turns each, primary will have estimated dc resistance of about 230 ohms... How is this wound? With 2 split primaries of
]|
first primary(2500 turns) ]|
]|
second primary(2500 turns) ]|
]
]=winding
| Core
Is this done in this way? IF so what are the benefits of having two primaries? Would it be better to split up the primaries into more segments i.e. 5 segments of 1000 turns
4. secondary will have 400 turns awg 22 enamel wire for 16 ohms, 200 turns for 4ohms and 280 turns for 8ohms, if you like, you can also split this into two coils, so that primary and secondary will interleave... What do you mean by split this into two coils so that primary and secondary will interleave. Could you show a sketch on how it is done
6. once the completed traffo is wired up and finished, you can install the ei cores, all the e's go together and there must be a gap between the e and the i to prevent dc saturation, you can use fish paper as a gapping material. Other than fish paper, is there a way to calculate how much gapping is needed for different dc currents allowable. How much microns is fish paper?
8. if you want to find out the primary inductance, you can use a capacitor of 1ufd in series with the primary coil, and feed a 50volt 60hz voltage taking measurements for voltage, you can determine inductance, bearing in mind that in a series ckt current flowing thru the cap is the same as that on the coils....
Is this how is done
50 volts 60hz signal-------|(1uf)|-----------primaries. The voltmeter measures the voltage across the primary windings? Does the end of the primary connect to any ware, i.e. ground? To determine inductance, the voltage of 50volts –(The reading from multimeter across the winding)/(current following thru the coils ) =XL. With XL =2*pi*f*L. L is found as f is frequency. Is my calculations correct
Thanks for the help
"I would like to wind a se trans. At the moment, my trans winder is doing power trans. Some how the bandwidth is 50-25Khz, for a 20va trans. The primary winding inductance is 4H. I measure a cheap audio trans se has a inductance of 8H therefore i would need to ask him to modify his power winding methods to do me an audiotrans i.e. gapping the EI. "
if you can post the details of your traffo here, like core size, core area, plate impedance, primary turns, i can comment as to how to get a better bandwith....
"primary winding will have 5000 turns awg 32 heavy formex split in two sections of 2500 turns each, primary will have estimated dc resistance of about 230 ohms... How is this wound? "
remember that this is for a plate load of 2.5kohms, spliting the primary into sections and interleaving with secondary winding is done to reduce leakage inductance that affects high frequency response....this technique can be found in most electrical engineering handbooks....the primary coils sections are all connected to form a single primary winding eventualy, so take care to observe polarity, meaning the start and finish of each coils is connected in the right sequence....
"Other than fish paper, is there a way to calculate how much gapping is needed for different dc currents allowable. How much microns is fish paper?"
the gapping between the e and the i's can be provided by thin sheet of fish paper, i never really measured its thickness, but is sufficient to keep the inductance of the winding at dc...
maintaining a high inductance of the primary winding is the key to good bass response, that is why having done preliminary calculations for primary number of turns, i would aim for maximum number of turns that can be squeezed in the traffo window and adjust the secondary windings accordingly....
hope i cleared things up or did i confure you some more?
cheers,
tony
one advantage of diy traffo making is that you do not have to make a lot of compromises found in commercial traffos!!!
if you can post the details of your traffo here, like core size, core area, plate impedance, primary turns, i can comment as to how to get a better bandwith....
"primary winding will have 5000 turns awg 32 heavy formex split in two sections of 2500 turns each, primary will have estimated dc resistance of about 230 ohms... How is this wound? "
remember that this is for a plate load of 2.5kohms, spliting the primary into sections and interleaving with secondary winding is done to reduce leakage inductance that affects high frequency response....this technique can be found in most electrical engineering handbooks....the primary coils sections are all connected to form a single primary winding eventualy, so take care to observe polarity, meaning the start and finish of each coils is connected in the right sequence....
"Other than fish paper, is there a way to calculate how much gapping is needed for different dc currents allowable. How much microns is fish paper?"
the gapping between the e and the i's can be provided by thin sheet of fish paper, i never really measured its thickness, but is sufficient to keep the inductance of the winding at dc...
maintaining a high inductance of the primary winding is the key to good bass response, that is why having done preliminary calculations for primary number of turns, i would aim for maximum number of turns that can be squeezed in the traffo window and adjust the secondary windings accordingly....
hope i cleared things up or did i confure you some more?
cheers,
tony
one advantage of diy traffo making is that you do not have to make a lot of compromises found in commercial traffos!!!
"50 volts 60hz signal-------|(1uf)|-----------primaries. The voltmeter measures the voltage across the primary windings? Does the end of the primary connect to any ware, i.e. ground? To determine inductance, the voltage of 50volts –(The reading from multimeter across the winding)/(current following thru the coils ) =XL. With XL =2*pi*f*L. L is found as f is frequency. Is my calculations correct"
to test for inductance, connect an ac voltage source that is convinient, i used 50volts ac @60 because it is convinient for me, you can try other voltages, but keep it low to be safe!!!
series connect the 1ufd capacitor and the primary winding and connect one end of the capacitor to the voltage source and one end of the primary winding to the other end of the voltage source...
now measure the voltage accross both the prmary winding and capacitor and list them down,
to get the current flowing thru the circuit, use this formula:
i=Vc/1000000/377
measure the resistance of the primary winding with an ohmeter,
use this formula to get the inductance:
Vl=sqrt iR + iXl
Xl=377L
all these calculations are done by hand, unlless you have and inductance meter...
to test for inductance, connect an ac voltage source that is convinient, i used 50volts ac @60 because it is convinient for me, you can try other voltages, but keep it low to be safe!!!
series connect the 1ufd capacitor and the primary winding and connect one end of the capacitor to the voltage source and one end of the primary winding to the other end of the voltage source...
now measure the voltage accross both the prmary winding and capacitor and list them down,
to get the current flowing thru the circuit, use this formula:
i=Vc/1000000/377
measure the resistance of the primary winding with an ohmeter,
use this formula to get the inductance:
Vl=sqrt iR + iXl
Xl=377L
all these calculations are done by hand, unlless you have and inductance meter...
if you can post the details of your traffo here, like core size, core area, plate impedance, primary turns, i can comment as to how to get a better bandwith....
The size of the 20va is similar to your trans in the pictures. The funny thing is that its a double bobbin winding where primaries and secondary are separated. And on the scope i get some hf. But when loaded with a 8 ohm load, the square waves don;t look nice on the hf a typical cheap audio trans waveforms. I not sure he has z11 core for this size but he has for bigger va size. I don't mind asking him to wind something using the z11 core for trial purposes. The trans was a 230volts:12.6volts which is about 2.6k:8. But i don't think he has gapped the core. How do you gapped the cores when E and I are interleaved ? FOr your method u presented did you interleave your E and I cores? If did not tHis would make it easier to gap the core, since e is on side and i is on the other side. I HAVE seen this done with chokes
remember that this is for a plate load of 2.5kohms, spliting the primary into sections and interleaving with secondary winding is done to reduce leakage inductance that affects high frequency response....this technique can be found in most electrical engineering handbooks....the primary coils sections are all connected to form a single primary winding eventualy, so take care to observe polarity, meaning the start and finish of each coils is connected in the right sequence....
I have also read this but do not really know how it looks like when you mean interleave. Is it possible you could show me a drawn sketch on this please. If not i could just ask him to wind them without interleaving as this would be hard and time consuming right?
Lets say i would like to wind a 25watts se trans with lots of primary inductance and i think i can get z11=m6 core. Could you help me to design one say for 2.5k:8 . also is it possible to guide me on the calculations u need to design a trans suchs as this so that i can try to do so on my own.
Thanks
The size of the 20va is similar to your trans in the pictures. The funny thing is that its a double bobbin winding where primaries and secondary are separated. And on the scope i get some hf. But when loaded with a 8 ohm load, the square waves don;t look nice on the hf a typical cheap audio trans waveforms. I not sure he has z11 core for this size but he has for bigger va size. I don't mind asking him to wind something using the z11 core for trial purposes. The trans was a 230volts:12.6volts which is about 2.6k:8. But i don't think he has gapped the core. How do you gapped the cores when E and I are interleaved ? FOr your method u presented did you interleave your E and I cores? If did not tHis would make it easier to gap the core, since e is on side and i is on the other side. I HAVE seen this done with chokes
remember that this is for a plate load of 2.5kohms, spliting the primary into sections and interleaving with secondary winding is done to reduce leakage inductance that affects high frequency response....this technique can be found in most electrical engineering handbooks....the primary coils sections are all connected to form a single primary winding eventualy, so take care to observe polarity, meaning the start and finish of each coils is connected in the right sequence....
I have also read this but do not really know how it looks like when you mean interleave. Is it possible you could show me a drawn sketch on this please. If not i could just ask him to wind them without interleaving as this would be hard and time consuming right?
Lets say i would like to wind a 25watts se trans with lots of primary inductance and i think i can get z11=m6 core. Could you help me to design one say for 2.5k:8 . also is it possible to guide me on the calculations u need to design a trans suchs as this so that i can try to do so on my own.
Thanks
hi,
you can not gap the core when the e and the i's are interleaved, unles you do it in groups of say 15 laminates, but better to do it with all the e's then fish paper, (thin Mylar sheet can also be used, or 3layers of scotch tape should be sufficient)
another tip, compute the number of turns for say 60 hertz, then factor in the lowest frequency you want, say 20 hertz, so you have a factor of 3, your traffo shall have 3x more number of turns...
this is how it should look like when interleaved:
cccccccc ---->secondary
---------- --->insulation
zzzzzzz ---->primary
---------- --->insulation
cccccccc ---->secondary
---------- ---->insulation
zzzzzzz ---->primary
---------- ---->insulation
===== ----->core
for the above design, i used an e-i 1 1/4 laminates stacked to a thickness of 1 1/4 in.
the ones in the priture is made from a e-i 1in laminates stacked to a thickness of 1 in. and has a different turns used....
you can not gap the core when the e and the i's are interleaved, unles you do it in groups of say 15 laminates, but better to do it with all the e's then fish paper, (thin Mylar sheet can also be used, or 3layers of scotch tape should be sufficient)
another tip, compute the number of turns for say 60 hertz, then factor in the lowest frequency you want, say 20 hertz, so you have a factor of 3, your traffo shall have 3x more number of turns...
this is how it should look like when interleaved:
cccccccc ---->secondary
---------- --->insulation
zzzzzzz ---->primary
---------- --->insulation
cccccccc ---->secondary
---------- ---->insulation
zzzzzzz ---->primary
---------- ---->insulation
===== ----->core
for the above design, i used an e-i 1 1/4 laminates stacked to a thickness of 1 1/4 in.
the ones in the priture is made from a e-i 1in laminates stacked to a thickness of 1 in. and has a different turns used....
hi,
finished your power traffo today, it has a copper foil electrostatic shield between primary and secondary widings...
copper foil banding around the traffo is used to reduce emi and stray fields...
the 5vac, and 12vac center-tapped windings are biffilliar wound to exactly locate the ceter tap, helpful in bucking hum...
tony
finished your power traffo today, it has a copper foil electrostatic shield between primary and secondary widings...
copper foil banding around the traffo is used to reduce emi and stray fields...
the 5vac, and 12vac center-tapped windings are biffilliar wound to exactly locate the ceter tap, helpful in bucking hum...
tony
Hi Joan2
According to your equation Vl=sqrtiR+ixl ,I could not follow through.
Would you explain more.
Thanks
ard3
According to your equation Vl=sqrtiR+ixl ,I could not follow through.
Would you explain more.
Thanks
ard3
hi,
this is to say that a practical inductor will have a dc resistance in series with its self iductance, and the voltage across the inductor, Vl is equall to the phytagorian sum of the voltages across each components....
these components are vectors, and that the induced voltage across the inductor is 90* out of of phase with the resistive voltage drop....
you can find more detailed info on electrical engineering books..
tony
this is to say that a practical inductor will have a dc resistance in series with its self iductance, and the voltage across the inductor, Vl is equall to the phytagorian sum of the voltages across each components....
these components are vectors, and that the induced voltage across the inductor is 90* out of of phase with the resistive voltage drop....
you can find more detailed info on electrical engineering books..
tony
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