SMD audio transformer

[Tubetec]

I saw these on ebay and wondered if they might do for a transformer based saturator in something like an effects pedal /stompbox . It might also be possible to use the inductance in filters ,

https://www.ebay.ie/itm/393431905494

 

[gyraf]

The only use I've found so far is for zero-field input transformers..

 

[Bo Deadly]

I saw these on ebay and wondered if they might do for a transformer based saturator in something like an effects pedal /stompbox . It might also be possible to use the inductance in filters

It's possible. The inductance is not pathetic but taking into consideration the source, you would definitely need to confirm the inductance and the consistency of quality in general. But they're cheap enough that I would just buy 10 and then test them each carefully. If they work as advertise (maybe accepting one or two dogs), you could drive them with a circuit like this one from Elliot Sound Products Negative Impedance Converters Fig 4:

This is the output equivalent of zero-field circuits gyraf is talking about.

If there is a decent amount of Nickel in the lams, it should be possible to get the distortion pretty low with a sharp onset of distortion above a certain level. That might be quite useful and for very little money especially if shipping is combined.

 

[Bo Deadly]

For the sake of completeness, here's how you can use negative impedance make a line input (from Revox PR99 schematic):



R108 is selected to be slightly less than DCR of secondary.

Although these particular transformers might not make great inputs because they're so small, the Z is low, there's no inter-winding shield, ....

But if you got double-zero distortion @50 Hz @-10dBu for an input or output, that could be pretty good for certain purposes. At least given the price. I mean $3 USD. Comon.

 

[moamps]

I would never use it as output transformer.

The only use I've found so far is for zero-field input transformers..

I would buy 4 of them, they are cheap, and try them as a microphone transformer; four primaries in parallel, four secondaries in series (two transformer's windings wired with polarities flipped for better EMI rejection ). And just a small metal box is needed ...

 

[gyraf]

I would never use it as output transformer.

I would buy 4 of them, they are cheap, and try them as a microphone transformer; four primaries in parallel, four secondaries in series (two transformer's windings wired with polarities flipped for better EMI rejection ). And just a small metal box is needed ...

Aah, nice angle on this one! Will try when I have a bit of time off production!

 

[abbey road d enfer]

I would never use it as output transformer.

I would buy 4 of them, they are cheap, and try them as a microphone transformer; four primaries in parallel, four secondaries in series (two transformer's windings wired with polarities flipped for better EMI rejection ). And just a small metal box is needed ...

I don't think it would really work. Four in parallels result in 0.25H inductance, which in turn results in a -3dB point at 125Hz with a 200r mic.

 

[abbey road d enfer]

I would never use it as output transformer.

Neither would I unless I'm satisfied with max level at 0dBu or less.

 

[abbey road d enfer]

you could drive them with a circuit like this one from Elliot Sound Products Negative Impedance Converters Fig 4:

This is the output equivalent of zero-field circuits gyraf is talking about.

It can hardly qualify as "zero-field" here. The THD vs. level curve is certain better with a negative-impedance driver, but the limitations due to saturation are there, whatever the driver circuit.

 

[abbey road d enfer]

The only use I've found so far is for zero-field input transformers..

Maybe that's what they are designed for, because I don't see much applications for them. Level specs are conspicuously missing...

 

[JohnRoberts]

Back in the 70s I experimented on my design bench trying to wrap op amps around cheap transformers to make them behave more like expensive transformers. It was a brief and unsuccessful experiment.

JR

 

[abbey road d enfer]

Back in the 70s I experimented on my design bench trying to wrap op amps around cheap transformers to make them behave more like expensive transformers. It was a brief and unsuccessful experiment.

JR

I think zero-field for inputs and negative impedance or tertiary NFB have shown the limits of what can be done in this direction. I don't expect anybody to come with a significantly better electronic band-aid.

 

[moamps]

I don't think it would really work. Four in parallels result in 0.25H inductance, which in turn results in a -3dB point at 125Hz with a 200r mic.

1.2H/4=0.3H
But it will work with U47, 251 or 44 wired for 50 or 30 ohms.

 

[abbey road d enfer]

1.2H/4=0.3H

Yes, I forgot the .2. Doesn't change much, though.

But it will work with U47, 251 or 44 wired for 50 or 30 ohms.

Or a Coles ribbon. Very narrow niche...

 

[JohnRoberts]

I think zero-field for inputs and negative impedance or tertiary NFB have shown the limits of what can be done in this direction. I don't expect anybody to come with a significantly better electronic band-aid.

And I didn't.

At the time my pursuit was making an improved low noise mic preamp. My hope was that I could grab some cheap voltage gain, level step-up from a cheap transformer but wrap an op amp around the whole shebang (technical term) to linearize it.

Like I already shared, it didn't work.

JR

 

[Tubetec]

Just wondering , could the cores of these mini transformers be placed close together so they couple magnetically and bring up the inductance ?

 

[gyraf]

Just wondering , could the cores of these mini transformers be placed close together so they couple magnetically and bring up the inductance ?

Sorry, no - closed magnetic loops.. You'd have to disassemble and rewind on bigger-stacked core

 

[Bo Deadly]

The Bourns LM-NP-1001-B1L is looks to be quite a bit bigger, it's 2.8H, Mouser describes it as "shielded" and it's even cheaper at less than $2 USD in quantity.

 

[volker]

The Bourns LM-NP-1001-B1L is looks to be quite a bit bigger, it's 2.8H, Mouser describes it as "shielded" and it's even cheaper at less than $2 USD in quantity.

I've used that one several times in guitar pedals, never measured anything though.