Capacitance Multiplier Power Supply

[kbyrne]

I am new to electronics and need assistance. Can anyone view this pdf and
advise if it will work. I got the idea off of Eliot Sound web site and cut his
schematic in half for only positive volts 33vdc to 36vdc and ground. It is for a working 12 watt old class AB amplifier design with hum. I am searching for a way to perfect the power supply as I revised the dual amplifier board with upgrades.
This design of power supply is for Class A but will it work with Class AB? Best Kevin

 

[AndrewT]

the circuit should work.
I think R1 & R2 are too low value.
The cap voltage when supplying 1mA of output current will be = Supply voltage*[10k/{10k+215+215}] = 0.96* Vsup.
The resulting 4% of Vsup is the maximum ripple allowed when current is supplied before the multiplier drops out of regulation.
Using 510+510 gives a 10% margin for ripple on the supply.
This is something you can experiment with after you have the amplifier running.
A scope to monitor the drop outs on the supply rail will show up the too small resistor values.

 

[kbyrne]

Thanks I will look at that. What is the meaning of start up surge current and how will it
affect transistors. I have two TIP'S TIP31C & TIP32C as output transistors. Will this type of power supply adversely affect any of the parts of a dual amplifier board. Best Kevin

 

[Mooly]

There are no real surge currents to worry about. The amp will actually see a slightly "delayed" rise time of the rail voltage. Use the specified TIP or 2N3055 as the series pass element. There should be no problems powering any amp from it.



What have the TIP31/32 to do with it ? Do you mean they are the amplifier output pair ?

 

[kbyrne]

Is this a good power supply design for other amps. even if I have to adjust voltages?
Best Kevin

 

[kbyrne]

There are no real surge currents to worry about. The amp will actually see a slightly "delayed" rise time of the rail voltage. Use the specified TIP or 2N3055 as the series pass element. There should be no problems powering any amp from it.



What have the TIP31/32 to do with it ? Do you mean they are the amplifier output pair ?

They are at the end of amplifier by the speaker outputs. I am inexperenced at all of that. Sorry

 

[Mooly]

Is this a good power supply design for other amps. even if I have to adjust voltages?
Best Kevin

Its really an active ripple filter and should work well.

Remember that most problems of "hum" in amplifiers are caused by incorrect wiring practice rather than ripple on the supplies.

 

[kbyrne]

Thank you for all replys. One of my origional problems I beleive was the wireing from power supply to amp. boards (two). I did not twist the wires at all just laid them side by side. Red, Black ect. I will check out all to what you said.
Best Kevin

 

[alayn91]

Hello,

I used this method to decrease the noise of a Philips 22RH270 pre-amplifier, on the RIAA phono inputs.
Because, at the earphone and volume CCW, we could hear the hum.

Here is the result:
The upper trace without mod,
The lower trace with a capacitance multiplier.

Regards.