After few tests and revisions (Rev 04) I updated the capacitor multiplier board I developed time ago
Despite you can place WIMA DC-Link film caps across the entire board, the use of high-quality electrolytic capacitors for the input and multiplier places is more efficient and convenient. I leave the expensive WIMA for the last cap after the SiC Mosfet:
The board has the flexibility to feed C2 with either the CCS or a simple resistor divider from the input HT. With the CCS you get above 120dB rejection of noise across the band average which is fantastic. However, there is no free lunch as you are obliged to drop 30 or 50V between the CCS for proper operation and good performance (HF in particular). The toll is carried on by the pass element (M5 or T5) which will have to dissipate the voltage drop across its shoulders.
The pass element is C3M0280090 which has a gm of 3.6S @3.5A or about 430mS @ 100mA. It also has very low Crss and output capacitance (Coss) which is ideal for good frequency response and filtering of HF coming from mains or raw supply.
I also added the feature of HV indication via an INS-1 neon bulb which is soldered straight on top of the PCB. Very handy to indicate normal operation.
With the 500k trimpot, I can regulate well a very stable voltage between 0 and 450V – won’t get close to that as it’s the limit of the electro caps and current protection ZTX458 transistor.
I’m using this board in my headphone amplifier. It’s very nice to have the slow current turn-on feature of this capacitor multiplier. With a 47uF capacitor multiplier you get above 120dB rejection. No point to increase the value of it.
I measured 300uV of noise at 250V for 50mA load. That’s -118dB which is pretty close to the Spice simulation. Extremely good!
My headphone amp is amazingly dead quiet with this HT multiplier. A great addition to it.
I made a couple of boards extra which I’m prepared to let go. Drop me an email if you’re interested.