Alternate First Watt Power Supply Schematic

[darrr]

@JeffYoung
You probably have an ltspice model. I have a request to You. Could you check what the 100hz ripple will be in this configuration: 33000uF capacitors and 0.47R resistors? Now the ripple is 170mVpp. Rail voltages under load +/- 21.7VDC from 18VAC on secondaries. Maybe it will be better?

 

[JeffYoung]

SPICE predicts 75mVpp.

 

[darrr]

Thank you Jeff
Do I correctly suspect there will be a bigger voltage drop?
Regards and Happy New Year

 

[JeffYoung]

Yes, but not material (~0.05V).

If you're willing to lose some voltage, 1 ohm resistors will nearly halve the ripple again at the loss of about 0.25V.

 

[darrr]

I have one more board so I can make a better version without desoldering. I wonder whether to install 4pcs 33000uF capacitors before the resistors and 47000uF on each rail after them . Will it be quieter than all 33mF versions?

 

[JeffYoung]

SPICE says 60mV w/0R47s; 35mV w/1R0s.

 

[darrr]

Is there any danger of increasing the capacity and resistance in the filter?

 

[JeffYoung]

More resistance leads to lower-voltage rails and more heat in the resistors.

More capacitance before the resistors puts more of a tax on the transformer (and fuses if you don't have a thermistor or other form of soft-start).

More capacitance after the resistors does too, but to a lesser effect.

 

[darrr]

Thank you Jeff.
I was thinking about a slb power supply but the costs will be much higher with a new transformer so I will work on your project

 

[starcat]

Rectifier boards are still on their way, but got 5pcs of these today. Thanks Jeff!

Any gerbers for the rectifier boards? Thanks

 

[JeffYoung]

If you mean the "Double Bridge" board, they're here:

https://www.diyaudio.com/forums/pass-labs/137145-f3-builders-thread-65.html#post5647859

 

[starcat]

Jeff, thanks for sharing all your excellent work!

Where do you get the fins for your F3 as posted in message #31?
Thanks again, appreciated.