For a circuit in my car I would need ground loop isolation for 2 stereo inputs. I'm looking for transformers of a reasonable quality and price, and I figure 10-20 euro sounds about right for this.
This series of transformers seems interesting: PC Mount - Plug-In Printed Circuit Audio Transformers On Triad Magnetics
The overview says the TY-141P operates from 20hz to 20 000hz, but once you open the datasheet it lists a 10% impedance matching from 200hz to 15 000hz. I'm confused because two different bandwidths are specified. What does this mean?
Farnell sells them for around 5 euro a piece: TY-142P - TRIAD MAGNETICS - TRANSFORMER, AUDIO, 0.1W | Farnell element14
Any other affordable suggestions are always gladly appreciated!
This series of transformers seems interesting: PC Mount - Plug-In Printed Circuit Audio Transformers On Triad Magnetics
The overview says the TY-141P operates from 20hz to 20 000hz, but once you open the datasheet it lists a 10% impedance matching from 200hz to 15 000hz. I'm confused because two different bandwidths are specified. What does this mean?
Farnell sells them for around 5 euro a piece: TY-142P - TRIAD MAGNETICS - TRANSFORMER, AUDIO, 0.1W | Farnell element14
Any other affordable suggestions are always gladly appreciated!
Maybe I should use a linear/analog optocoupler instead. A friend says its cheaper and performs better.
Transformers are inherently less capable of transferring power with low distortion at low frequencies. If you want good performance at low frequencies you essentially overbuild them as compared to a design that need only work well at higher frequencies.
That said, its possible to obtain very good performance from transformers, at a price. Jensen Transformers is reputed to be one of the finest suppliers of audio transformers.
Just bought some Pyramid N21 isolation units from eBay for about $5 each. Tested by REW in a loop with nothing else in the loop except, of course, the Mac DAC and a $25 USB ADC.
The horizontal lines are 20dB apart. FR and distortion look good to me (as a real-world audiophile) and the transformer is probably the least weak link in the test set-up.
Ben
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Isolation transformer are more commonly used where mains electricity causes interference voltages on difference sources and receivers.
In a car there is no mains electricity, so I have to ask, why do you need isolations transformers?
In a car there is no mains electricity, so I have to ask, why do you need isolations transformers?
If "you" is pointing to me, the answer is that my application is my complicated vacation condo system. There's a lot of praise, almost always laudatory, about signal isolation. Yes, nearly fully removed a bit of buzzing form my speakers when connected south of the pre-amp. From my graph there doesn't seem to be a downside. (And much less laudatory is the discussion of mains-power isolation transformers.)
The web also has mostly favourable posts about reducing noise in car audio systems such as in satellite reception, etc., perhaps arising from ignition and charging systems.
Ah.... how well I remember the hash I heard with my fist CD-ignition* kit, that I installed in 1968 in my 1960 Jaguar Mk II. Much helped the Jag because it replaced Lucas parts. You know all those Lucas Electrics jokes... whole websites devoted to 'em.
Ben
*CD, as in capacitor discharge
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First car I ever bought was a 1959 Mk-I Jag. The style just before yours. The ignition system was the least of its troubles. 🙄 I think it had an AM radio, single speaker.
I was trying to comment on Teus request
I can't understand why a mains solution is being applied inside a car where there is no mains electricity.
Andrew, it's nothing to do with mains, but rather - surprisingly - ground loops.
The audio system is referenced to 0V (chassis) at multiple points in the vehicle. The result tends to be a whine inline with engine speed.
The audio system is referenced to 0V (chassis) at multiple points in the vehicle. The result tends to be a whine inline with engine speed.
Yes, currents around the chassis are an issue even for a vehicle as small as a motorcycle. On my bike*, a lot of ground wires running around to maintain what I think is called a star ground system, with certain critical circuits grounded only at a single point on the chassis (or what rudimentary object passes for a chassis in a modern bike). An issue for sound and for all the digital signals today and esp as ignition put out so much treble.
Ben
*1999 BMW R1100S (biking 55 seasons, coast to coast)
Ben
*1999 BMW R1100S (biking 55 seasons, coast to coast)
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