Constant Voltage Transformer Operation?

Started by amdx in sci.electronics.design9 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...


EMI-resistant input transformer design

Started by Spehro Pefhany in sci.electronics.design5 years ago 27 replies

Hi, all:= Okay, so I have a very low level very low noise narrow band signal at < 1MHz coming in over shielded twisted pair with a fairly...

Hi, all:= Okay, so I have a very low level very low noise narrow band signal at < 1MHz coming in over shielded twisted pair with a fairly active EMI environment. I've designed an step-up input transformer that works nicely at the front end- balanced to single-ended. I'm concerned about common mode noise coupling through the transformer. Should I a) center tap the primary


Transformer-less power supply question

Started by Daku in sci.electronics.design10 years ago 21 replies

Could some electronics guru please clarify the following ? All traditional transformer-less power supply designs suffer from the AC mains...

Could some electronics guru please clarify the following ? All traditional transformer-less power supply designs suffer from the AC mains isolation issue. I was wondering how viable the following solution would be to tackle this issue. In traditional transformer-less power supply designs, the connection to the 'live' is made via a parallel RC combination, where R is very high and C limits th...


transformer/inductor design

Started by Simon S Aysdie in sci.electronics.design6 years ago 1 reply

http://coefs.uncc.edu/mnoras/tr_design/ There is a newer one. Author has good transformer link page: http://www.kgmagnetics.com/?q=node/9

http://coefs.uncc.edu/mnoras/tr_design/ There is a newer one. Author has good transformer link page: http://www.kgmagnetics.com/?q=node/9


Digital Communication across transformer allready powering a circuit

Started by Klaus Kragelund in sci.electronics.design5 years ago 24 replies

Hi So I have a transformer that is powering a circuit. It's running at > 200kHz I need to add downstream and upstream digital communication...

Hi So I have a transformer that is powering a circuit. It's running at > 200kHz I need to add downstream and upstream digital communication at fairly high speed to the transformer Downstream, I was thinking just change the frequency from 200kHz to say 300kHz for just a couple of periods. That can easily be detected. But upstream, the "normal" way is to modulate the load, like in t


TRANSFORMER EFFICIENCY

Started by Anonymous in sci.electronics.design8 years ago 14 replies

How do you derive the efficiency of a transformer from the first principle of electric circuit.

How do you derive the efficiency of a transformer from the first principle of electric circuit.


Connecting three single phase transformers to get single 3 phase transformer

Started by Anonymous in sci.electronics.design4 years ago 18 replies

Could some guru on this newsgroup please help ? I am trying to create a simple 3 phase transformer from 3 single phase transformers. I am unsure...

Could some guru on this newsgroup please help ? I am trying to create a simple 3 phase transformer from 3 single phase transformers. I am unsure about the inter-connection of these three transformers. Consider the 'delta' configuration: Each single phase transformer has 2 terminals on the primary side, and three on the secondary. So for the primary side, the three windings are connect...


transformer secondary coupling

Started by Jamie M in sci.electronics.design10 years ago 49 replies

Hi, If the secondary of a push-pull ferrite transformer requires significant HV clearance from the ferrite core will there still be enough...

Hi, If the secondary of a push-pull ferrite transformer requires significant HV clearance from the ferrite core will there still be enough coupling for it to operate efficiently assuming the primary is wrapped right onto the core? Also is it possible to use a simple ferrite rod as a transformer at least somewhat efficiently? For making a secondary with high clearance a ferrite rod is a l...


Our power went out tonight

Started by amdx in sci.electronics.design8 years ago 12 replies

My wife called me about 5:30 saying the power in our neighborhood was out. This was a bit of a concern because she just loaded 630 pounds of...

My wife called me about 5:30 saying the power in our neighborhood was out. This was a bit of a concern because she just loaded 630 pounds of shrimp in one of our freezers earlier in the day. I arrived home a little after 6:00 and a power co. employee was looking over the transformer across the street. At 6:40 he told us the transformer was bad and they would replace it, and we would have ...


transformer K in LT Spice

Started by Anonymous in sci.electronics.design2 years ago 6 replies

I recall seeing, somewhere, that LT Spice may handle a transformer with K=1 different from one where K

I recall seeing, somewhere, that LT Spice may handle a transformer with K=1 different from one where K


IIR constant phase shift network, absolute vs. relative phase

Started by bitrex in sci.electronics.design2 years ago 14 replies

In the Hilbert transformer-based phase shifting network implementation a la: They measure the shift of the final y output as a relative...

In the Hilbert transformer-based phase shifting network implementation a la: They measure the shift of the final y output as a relative phase with respect to the I output of the digital Hilbert transformer. It looks like it's possible to also make an absolute phase shift with respect to the input signal to the transformer by adjusting


Design Me A Transformer, I Will Pay

Started by Anonymous in sci.electronics.design2 years ago 111 replies

I have tried to figure out how to do this but my education lacks. What do people like me do when they need something done they can't do ? Pay...

I have tried to figure out how to do this but my education lacks. What do people like me do when they need something done they can't do ? Pay someone. I need an audio transformer, actually a center tapped choke. I can't seem to source it so custom mad, oh well. You get what you pay for. This has to be high quality for audio, not saturate or any of that and I need a low DCR.


Current Transformer Question

Started by Jim Thompson in sci.electronics.design7 years ago 29 replies

Suppose I have a current transformer where the primary current is half-wave rectified. In the ideal (Spice, natch ;-), nothing will show on...

Suppose I have a current transformer where the primary current is half-wave rectified. In the ideal (Spice, natch ;-), nothing will show on the secondary. In real life, what would I see? ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | A...


Cute transformer

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

I found this inside a cheap AM/FM alarm clock with a smashed...

I found this inside a cheap AM/FM alarm clock with a smashed display: https://www.dropbox.com/s/26ttm70lfngtbm7/IMG_20150723_114530.jpg?dl=0 I was a bit surprised that there was a transformer inside at all - I expected it to be powered directly off the line. It appears to be a 120:12.6 piece, though I'm not sure of the turns ratio. Rated for 100mA maybe? It seems to do OK running th...


Request help in selecting transformer from Digikey

Started by Anonymous in sci.electronics.design8 years ago 10 replies

I apologize if my queries sound silly, so pardon me. The truth is that I have used transformers in my work for a long time, but never bought it...

I apologize if my queries sound silly, so pardon me. The truth is that I have used transformers in my work for a long time, but never bought it myself -- someone else bought the required ones as per my specifications. Now I have to buy some from an online store as Digikey, and am confused, with all details presented to me. I want a 120 V AC -> 9 - 0 - 9 Volt 2 Amp AC transformer. I am


gEDA PCB footprints for potted transformers.

Started by Johann Klammer in sci.electronics.design2 years ago 1 reply

I looked at that gedafootprints site but they only had one(1) transformer of the wrong size. So here's my .inc file for those. Beware....

I looked at that gedafootprints site but they only had one(1) transformer of the wrong size. So here's my .inc file for those. Beware. dimensions were hand transcribed from a pdf. # single output safety transformer \n $1: canonical name # $2: nameonpcb # $3: value # $4: A (mechanical dimensions in um) # $5: B # $6: C # $7: D # $8: E # $9: F # $10: pin size define(`PKG_BLOCK1


Current Transformer/Sensor at 60Hz

Started by Jim Thompson in sci.electronics.design5 years ago 7 replies

I need to sense ~200mA AC at 60Hz. Is there a CT rated for such use or should I just cobble up an old filament transformer? ...

I need to sense ~200mA AC at 60Hz. Is there a CT rated for such use or should I just cobble up an old filament transformer? ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | S...


Power transformer standards (safety etc.,) for US

Started by Anonymous in sci.electronics.design8 years ago 5 replies

Could some electronics guru please provide pointers to standard power transformer(for bench top power supplies) standards, specifically for the...

Could some electronics guru please provide pointers to standard power transformer(for bench top power supplies) standards, specifically for the US ? Each time I Google for it, I get directed to some IEC Web sites, but I want information specific to the US. Any hints, suggestions would be of immense help.


Video Isolation Transformer

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

I've just repaired a transformer based video isolation unit. This paticular unit has centre tapped primary and secondary windings with a series...

I've just repaired a transformer based video isolation unit. This paticular unit has centre tapped primary and secondary windings with a series RC network between the two taps (see the sketch at http://tinyurl.com/pgwovlf ). I can't quite see why these components have been added - any ideas?


oscillator for driving a transformer

Started by panfilero in sci.electronics.design9 years ago 12 replies

Hello, I'd like to drive a small high frequency transformer at around 100kHz-300kH= z with a 24Vpk signal, I tried building up an astable...

Hello, I'd like to drive a small high frequency transformer at around 100kHz-300kH= z with a 24Vpk signal, I tried building up an astable multivibrator with a = couple of caps and transistors but i couldn't get it to drive the transform= er, it wouldn't even make anything close to a nice square wave.... anyone k= now of a better simple oscillator circuit I could use to do this? thanks! ...