Transformer Question

Started by Anonymous in sci.electronics.design9 months ago 91 replies

I was looking at the commercial isolation transformers and they are very costly, so I decided to build my own. After all, all they are is...

I was looking at the commercial isolation transformers and they are very costly, so I decided to build my own. After all, all they are is a transformer with a power cord on the primary and an outlet (and fuse) on the secondary. And I already have an enclosure to put it in. I'm looking at a bare transformer to use as an 120v isolation Transformer. (120v in, 120v out). The transformer primar...


Little 1:10 audio transformer as HV transformer

Started by Jan Panteltje in sci.electronics.design6 years ago 125 replies

Little 1:10 audio transformer as HV transformer Thse are small transformers with a ferrite core, specified as 6H secundair, and turns ratio...

Little 1:10 audio transformer as HV transformer Thse are small transformers with a ferrite core, specified as 6H secundair, and turns ratio 1:10. (conrad nr 516260). The idea was to make 400 V from 5 V with a PIC. That requires at least 40V peak primary. I tried some BC547B, but changed to a IRLZ434N MOSFET, as this one has the reverse diode for free, I tried many frequencies and pulse w...


Current transformer with good coupling?

Started by Klaus Kragelund in sci.electronics.design6 years ago 15 replies

Hi I am working on a design in which we need to have very good coupling from primary to secondary of a transformer. The transformer is used...

Hi I am working on a design in which we need to have very good coupling from primary to secondary of a transformer. The transformer is used as a current transformer and we must have very high accuracy from primary to secondary, so we have the same current on the output also. We are using a toroid xformer with bifilar windings (4 wires in parallel to yield a transformer with 4 windings...


Transformer power rating

Started by Anonymous in sci.electronics.design2 weeks ago 14 replies

A radio museum thread contributor says: "Note the mains transformer power rating is at 50Hz or 60Hz, so it can handle higher audio power as on...

A radio museum thread contributor says: "Note the mains transformer power rating is at 50Hz or 60Hz, so it can handle higher audio power as on average it's more than 10x the frequency and the core size needed is much less (that's one reason SMPSU uses 25KHz to 2MHz, to use a small transformer). A toroidal transformer needs well matched bias currents, avoid them." I'm not convince


Toroidal Audio Transformer

Started by hamilton in sci.electronics.design6 years ago 3 replies

I am looking at replacing an audio transformer. The size I have now is larger than my case. I need to have a smaller transformer and thought...

I am looking at replacing an audio transformer. The size I have now is larger than my case. I need to have a smaller transformer and thought a toroid type might work. Has anyone worked with this type of audio transformer ? Are there any web sites for calculating the size / power output ? I would like 10-15 watts output. Thank you hamilton


RF transformer

Started by Robert Baer in sci.electronics.design4 years ago 40 replies

I understand, that with the proper winding configuration, that a 90 degree phase shift can be achieved between primary and resonant...

I understand, that with the proper winding configuration, that a 90 degree phase shift can be achieved between primary and resonant secondary. That is done with a tapped secondary on a FM discriminator transformer. What are the guidelines and requirements needed to construct such a transformer at a given frequency OTHER than the standard 10.7Mhz? Say, on a form in the one inch d...


Current transformer

Started by Tim Williams in sci.electronics.design6 years ago 114 replies

Would've been nice if I had known a current transformer isn't a very good transformer. Instead of two terminals, it acts more like a single...

Would've been nice if I had known a current transformer isn't a very good transformer. Instead of two terminals, it acts more like a single terminal, with your poor burden resistor caught in the middle. Ah well, such is basic research... Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms


Toroidal Transformer Screening

Started by Syd Rumpo in sci.electronics.design2 years ago 11 replies

Hi Another magnetics question! I have a SMPS which uses a toroidal ferrite transformer. It switches at ~100kHz, works very well, it's not...

Hi Another magnetics question! I have a SMPS which uses a toroidal ferrite transformer. It switches at ~100kHz, works very well, it's not my design and I can't change it. However, it introduces noise at about 50kHz onto/into my electronics which causes a problem. After much experimentation, I found that putting an earthed screen around the transformer kills the problem quite dra...


Current transformer

Started by Sylvia Else in sci.electronics.design2 years ago 42 replies

I was looking for a cheap clip-on current transformer to use to monitor my power usage, and I found...

I was looking for a cheap clip-on current transformer to use to monitor my power usage, and I found this: http://efergy.com/au/products/accessories/microjackplug-extra-sensor#.VmZZQF42GVI which I guessed (correctly) was a current transformer. I that have no intention of using it with Efergy's products, since they don't seem concerned about the voltage, which can vary somewhat from n...


Build your own Over Unity Motor

Started by The Flavored Coffee Guy in sci.electronics.design10 years ago 82 replies

Just remember this, a transformer is designed for a purpose and it can be either a step up transformer or a step down transformer. Everything...

Just remember this, a transformer is designed for a purpose and it can be either a step up transformer or a step down transformer. Everything else you need to know is here. Go to this web site to pick up the basic theory: http://elgersmad.homestead.com/files/resonance/transformer_motor_theory.pdf Go to this link to understand that it will work: http://www.gutenberg.org/files/11498/1149...


Using SSR to switch transformer

Started by Arlet Ottens in sci.electronics.design10 years ago 39 replies

Hello, I'm considering using an SSR to switch the primary side of a transformer. The transformer is a toroid, 230V -> 27V. The secondary...

Hello, I'm considering using an SSR to switch the primary side of a transformer. The transformer is a toroid, 230V -> 27V. The secondary side is fixed to a 1 Ohm nichrome wire heating element. I've read some articles that say switching on at zero crossings causes a high inrush current, and that it's best to switch on at peak voltage. If I follow this advice, are there any other issu


0.2MHz - 2MHz step up transformer

Started by Paul Jackson in sci.electronics.design6 years ago 80 replies

I am looking for an impedance matching transformer that will convert the 50 Ohm output of my function generator and to a 1K Ohm...

I am looking for an impedance matching transformer that will convert the 50 Ohm output of my function generator and to a 1K Ohm resistive load. That provides a 20x step-up as well, so with losses 10V yields maybe 100V. Frequency range is anywhere between 200KHz to 2MHz. Required current, up to 20mA. I would definitely prefer a ready-made transformer. Does anyone know under what app...


50 ohms to 0.02 ohm transformer

Started by amdx in sci.electronics.design1 year ago 37 replies

I want to build a 50 ohm to 0.02 ohm transformer. It needs a 50 to 1 turns ratio. It takes a low A sub L core to make such a thing. I have a...

I want to build a 50 ohm to 0.02 ohm transformer. It needs a 50 to 1 turns ratio. It takes a low A sub L core to make such a thing. I have a toroid with an A sub L of 75. That only needs 29 turns for my frequency of interest 500KHz to 1700kHz. I also have some potcores that I could gap to lower the A sub L. What would make a better transformer a toroid or a gapped potcore? I plan 50...


Air core transformer question -- help

Started by Anonymous in sci.electronics.design2 years ago 20 replies

Could some electronics guru please provide some hints/suggestions to the following ? First, I built a simple DC-> AC push-pull inverter with a...

Could some electronics guru please provide some hints/suggestions to the following ? First, I built a simple DC-> AC push-pull inverter with a 12 Volt 7AH sealed lead acid cell battery. The output transformer is a 120 Volt(primary) and 6-0-6 1.5 Amp (max) secondary. This configuration worked fine, and a 60 Watt incandescent lamp connected to the transformer output terminals pr


calculating transformer saturation

Started by Jamie Morken in sci.electronics.design10 years ago 6 replies

Hi, I am trying to calculate the max number of turns that I can use in a transformer at a given current using the formula from...

Hi, I am trying to calculate the max number of turns that I can use in a transformer at a given current using the formula from this page: http://info.ee.surrey.ac.uk/Workshop/advice/coils/#turn N = Bsat*le / (?*I) where: N = turns Bsat = saturation flux density (Tesla) le = effective length (meters) u = permeability (Henries/meter) I = current (Amps) for the transformer I ha


Small transformers and LTSpice simulation

Started by Grant in sci.electronics.design7 years ago 30 replies

I have a design that could use three or four winding toroid transformer. In the LTSpice notes they suggest keeping the transformer coupling...

I have a design that could use three or four winding toroid transformer. In the LTSpice notes they suggest keeping the transformer coupling at 1.0 or -1.0 otherwise there's lots of high frequency noise generated, I'm not sure if that's real world, or the simulation going silly? What I'm wondering is just how much coupling should I expect to see in a real world transformer of around f...


Xmotors

Started by Kalarama in sci.electronics.design9 years ago 13 replies

I recently noticed my Crown audio amplifier uses a combination transformer/motor as the cooling fan. The transformer also feeds bias/control...

I recently noticed my Crown audio amplifier uses a combination transformer/motor as the cooling fan. The transformer also feeds bias/control circuitry. Neat! So, if I may presume, if/when the fan motor seizes, the transformer's primary winding fuse blows, also interrupting +/- 24vdc and +/- 15vdc, the bias voltages are turned off, effectively dropping the amplifier into standby. Cl...


Ignition coil for flashtubes as HV transformer?

Started by Jan Panteltje in sci.electronics.design6 years ago 23 replies

Ignition coil for flashtubes as HV transformer? I want to make a few hundred volts at very low current, a few uA. These trigger tubes for flash...

Ignition coil for flashtubes as HV transformer? I want to make a few hundred volts at very low current, a few uA. These trigger tubes for flash tubes seem to do 200V in 4000V out, by discharging a cap in the primary. They are dirt cheap here. So the transformer ratio is 1 : 20. I am thinking about PWMing one to make 500 V peak from 5 V DC. As I do not have one yet, does anybody know the indu...


What is special about a wall wart transformer

Started by Anonymous in sci.electronics.design7 months ago 18 replies

What is special about a wall wart transformer, as compared to a standard iron-core transformer ?

What is special about a wall wart transformer, as compared to a standard iron-core transformer ?


Combined resonant inductor and transformer in LLC halfbridge

Started by powerampfreak in sci.electronics.design3 years ago 2 replies

I am designing a halfbridge LLC converter. Due to different reasons I want to use transformer leakage as resonant indu= ctor. As production are...

I am designing a halfbridge LLC converter. Due to different reasons I want to use transformer leakage as resonant indu= ctor. As production are concerned, what are the best way to achieve the tightest = results? I have made some experiments, with a 2-sectioned bobbin, but as soon as the= transformer are wound, it's no way of "trimming" or adjusting the leakage. I then made a new transforme...