Transformer Question

Started by Anonymous in sci.electronics.design4 years 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.design9 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...


Transformer power rating

Started by Anonymous in sci.electronics.design3 years 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


RF transformer

Started by Robert Baer in sci.electronics.design7 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...


Cooling of overloaded transformer

Started by Klaus Kragelund in sci.electronics.design3 years ago 97 replies

Hi When I go to the states, I usually buy white goods, half price than in Europe So I have a 600W 230V to 115V transformer installed in a...

Hi When I go to the states, I usually buy white goods, half price than in Europe So I have a 600W 230V to 115V transformer installed in a cabinet Now I have bought a 1300W toaster Instead of buying a new transformer, I am seriously considering just overloading it, but then keeping the heat down by forced convection, namely a fan Anyone tried overloading transformers before? Rega...


Current transformer

Started by Tim Williams in sci.electronics.design9 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.design5 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...


Overvoltage on transformer secondary

Started by Anonymous in sci.electronics.design3 years ago 47 replies

I his article about troubleshooting () Bob Pease writes: : If the power line switch was turned off at exactly the wrong time of : the cycle,...

I his article about troubleshooting () Bob Pease writes: : If the power line switch was turned off at exactly the wrong time of : the cycle, the flux in the transformer steel core could be : strored at high level. Then, if the line power switch was : reconnected at exactly the wrong time in the cycle, the flux : in the transformer would ontinue to build up until the : transformer saturate...


Current transformer

Started by Sylvia Else in sci.electronics.design5 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...


high-voltage transformer

Started by Winfield Hill in sci.electronics.design12 months ago 12 replies

My 1:1 high-voltage transformer is coming along well. This is to make 5V, 12V, or whatever at high voltages. I'll be using it at 6kV, but...

My 1:1 high-voltage transformer is coming along well. This is to make 5V, 12V, or whatever at high voltages. I'll be using it at 6kV, but it's passing tests at 9kV, and I'll do a weekend at 11kV before pronouncing it OK. The transformer is a small 50-cent common-mode choke, TAIYO YUDEN p/n TLF9UA102W0R8K1, footprint only 11x17mm. The pins are spaced 8mm. We potted it with vacuum ai...


0.2MHz - 2MHz step up transformer

Started by Paul Jackson in sci.electronics.design9 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.design4 years 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.design5 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


Small transformers and LTSpice simulation

Started by Grant in sci.electronics.design9 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...


What is special about a wall wart transformer

Started by Anonymous in sci.electronics.design4 years 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.design6 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...


2.5KVA transformer on square wave 1000hz mains

Started by raypsi in sci.electronics.design8 years ago 18 replies

I just bought a 50/60 hz transformer rated 575VAC pri to 230VAC sec rated at 2.5KVA on ebay. I remember reading some time ago that transformer...

I just bought a 50/60 hz transformer rated 575VAC pri to 230VAC sec rated at 2.5KVA on ebay. I remember reading some time ago that transformer companies rated their transformers to 1000 hz. I'm needing like a 3KVDC at about 1.5KVA semi regulated supply but don't like to use lots of mfd's of filtering at higher voltages to get there. For a 4X1 PA ima building. So I figure getting there by...


Bandaxall Oscillator

Started by Kooner in sci.electronics.design8 years ago 15 replies

Hello, I made a Bandaxall Class D Oscillator with a 11mm x 7mm pot core transformer and it works quite well. The input is 8VDC and...

Hello, I made a Bandaxall Class D Oscillator with a 11mm x 7mm pot core transformer and it works quite well. The input is 8VDC and the secondary output is 800V peak to peak. The transformer is very difficult (for me) to wind because the secondary uses #46 awg wire and it breaks easily. Also, I would like to use a shorter transformer, around 5mm tall. There are smaller pot cores but ther...


transformer core flux propagation speed

Started by Jamie M in sci.electronics.design8 years ago 55 replies

Hi, I was curious about how fast the winding induced flux will propagate through a transformer core (ie a ferrite core) assuming a...

Hi, I was curious about how fast the winding induced flux will propagate through a transformer core (ie a ferrite core) assuming a single primary winding on a toroid? Would it be possible to make a resonant transformer using core geometry (ie replacing the toroid with a shape that has a sine wave on the toroid). If the switching frequency is high enough, maybe it is possible to utilize t...


Constant Voltage Transformer Operation?

Started by amdx in sci.electronics.design8 years ago 7 replies

I recently repaired a marine battery charger. It was set up to charge 3 separate 12v batteries. The repair was simple the charger had a...

I recently repaired a marine battery charger. It was set up to charge 3 separate 12v batteries. The repair was simple the charger had a *shorted 40uf 660v ac capacitor. The capacitor is connected across a winding on the transformer. This is the usual constant voltage transformer configuration. This is the extent of what I think I know. Can someone describe the operation of a constant vo...