Dual mono PSU. - Page 2

trobbins · 1st December 2020, 11:48 PM

What are R3-C6 and R4-C5 for?

What are CX1 and CS1 and RS1 for?

Perhaps a schematic showing the Tx and secondary windings, and snubber parts, and the pcb and its parts would avoid confusion.

Sebastiaanm · 2nd December 2020, 12:15 PM

A quick sketch of the schematic

trobbins · 2nd December 2020, 12:24 PM

The snubber is usually a C-RC, and is placed across each secondary half-winding, as it is the energy in each half-winding leakage inductance that needs to be constrained.

Sebastiaanm · 2nd December 2020, 03:46 PM

My fault, the first resistor on the left should be a capacitor.

In the pcb schematic it is a capacitor

I can try to put a snubber circuit on each half winding. don't know it's gonna fit, but i can try.
I read in different forums that it's no problem to put one snubber circuit over the outer taps, that's why i draw just one.

pinholer · 2nd December 2020, 04:03 PM

Check the power dissipated by the current limiting resistors for the LEDs. Don't want to let the smoke out.

Sebastiaanm · 2nd December 2020, 06:45 PM

It will indeed make it a smokemachine

The led is rated 20mA 3.2V.
4k7 with 50v will result in 10mA trough the led and near 0.5w in the resistor. I better pick a 0.5w or 1w resistor. Thnx

trobbins · 3rd December 2020, 12:50 AM

Most new LEDs will happily operate at 2-5mA - perhaps worth checking LED intensity before settling on a resistor dropper value. Perhaps aim for resistor dissipation of no more than 40-50% of rating to avoid brown marks appearing on pcb over the years.

Quote:

Originally Posted by Sebastiaanm

I read in different forums that it's no problem to put one snubber circuit over the outer taps, that's why i draw just one.

The snubber is a means of suppressing noise. How well people implement a snubber may be up to practical issues like yours, and once they implement a snubber who knows how they determine if there was a benefit or not ......

Unless you are very dedicated and have tools available, you won't know if your transformer has a significant level of leakage inductance, or if your power supply configuration is pushing a high level of peak rectifier current and turn-off dI/dt, or if your implementation is leaking rectification noise in to the audio path, and it would have to be a severe case for your ears to pick out any difference.

Sebastiaanm · 3rd December 2020, 05:15 PM

Thnx for the info,i will try different resistor value's for the led. Maybe 10k, if it's emits light is good enough

The snubber circuit will be on each half winding, it fits on the pcb.
I will try the quasimodo circuit on the transformer later

Next week i'm gonna mill the pcb, all parts are arrived.

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1st December 2020, 11:48 PM	#11
trobbins diyAudio Member Join Date: Feb 2009 Location: Melbourne, Oz	What are R3-C6 and R4-C5 for? What are CX1 and CS1 and RS1 for? Perhaps a schematic showing the Tx and secondary windings, and snubber parts, and the pcb and its parts would avoid confusion.

2nd December 2020, 12:24 PM	#13
trobbins diyAudio Member Join Date: Feb 2009 Location: Melbourne, Oz	The snubber is usually a C-RC, and is placed across each secondary half-winding, as it is the energy in each half-winding leakage inductance that needs to be constrained.

2nd December 2020, 03:46 PM	#14
Sebastiaanm diyAudio Member Join Date: Dec 2019 Location: limburg	My fault, the first resistor on the left should be a capacitor. In the pcb schematic it is a capacitor I can try to put a snubber circuit on each half winding. don't know it's gonna fit, but i can try. I read in different forums that it's no problem to put one snubber circuit over the outer taps, that's why i draw just one.

2nd December 2020, 04:03 PM	#15
pinholer diyAudio Member Join Date: Mar 2010 Location: Okanagan Valley	Check the power dissipated by the current limiting resistors for the LEDs. Don't want to let the smoke out.

2nd December 2020, 06:45 PM	#16
Sebastiaanm diyAudio Member Join Date: Dec 2019 Location: limburg	It will indeed make it a smokemachine The led is rated 20mA 3.2V. 4k7 with 50v will result in 10mA trough the led and near 0.5w in the resistor. I better pick a 0.5w or 1w resistor. Thnx

3rd December 2020, 05:15 PM	#18
Sebastiaanm diyAudio Member Join Date: Dec 2019 Location: limburg	Thnx for the info,i will try different resistor value's for the led. Maybe 10k, if it's emits light is good enough The snubber circuit will be on each half winding, it fits on the pcb. I will try the quasimodo circuit on the transformer later Next week i'm gonna mill the pcb, all parts are arrived.