audio-talk

I use the Lumburg ones in the Ref Phono.

1) with a DC heated DHT using Andrews DC board, is there a benefit to using virtual cathode resistors When this question was asked, my answer was "as there is no disadvantage to doing so, and some theoretical justification, then may as well" Now there is a downside, that justification is removed. 2...

And used Schottky diodes.

I would expect the bridge to impact the sound, but should be easy to prove

Bet it wont be easy to "prove" given that you expect it will

No external power, so the led lights IF the difference between the voltages at the ends of the resistors differs by more than 3 diode drops plus the drop over the current limiting resistor. Interesting, but wouldn't that be directly in the music path ? Yep, thats it, throw a cap across it of you li...

You could try a LED inside a bridge rectifier. ok quick bit of googling and ... Capture.PNG Is that something like what you had in mind ? No, literally a LED inside a bridge rectifier. Rectifier with ac terminal one to each resistor cathode, LED with dropper resistor between the bridge + and - term...

You could try a LED inside a bridge rectifier.

Yes, you are trying to detect when the two currents are different, you have two equal resistors, one in each current with a common tail, if the currents are different, the voltage at the top of each resistor will be different.

RhythMick wrote: ↑

Fri Feb 15, 2019 9:22 am

Or combine the outputs in a NOR. Single led lights if either of the comparator outputs goes low, but not both.

In that case you may as well just compare the voltages on the top of the to sense resistors. What is unknown is will it trigger with a audio signal.

It would light the LED's when you turn the amp off.

RhythMick wrote: ↑

Thu Feb 14, 2019 4:37 pm

Isolated means the output is floating, right ? So I can ground to the top of the cathode resistor per the diagram. I know that's obvious, just checking my terminology.

Well, you can connect to the cathode resistor without grounding anything which I think is what you are asking.

These sort of isolated supplies can be great for providing a floating supply from a existing DC supply.

https://uk.rs-online.com/web/p/isolated ... s/3965174/

The electrostatic screen is to prevent capacitive coupling between the primary and secondary. Doesn't affect hum field.

Just try rotating one of the transformers and see if the hum changes.

Is it hum (50Hz) or does it have edges? (100Hz+charging)

RhythMick wrote: ↑

Wed Feb 13, 2019 2:30 pm

Nick wrote: ↑

Wed Feb 13, 2019 2:24 pm

Transistors never fully turn off. I would consider the resistor on the same side as the LED.

Ok thanks

And consider taking the collector of the PNP to the emitter of the NPN.

Transistors never fully turn off. I would consider the resistor on the same side as the LED.