PSU for BA1, BA2, BA3 front-end

[JeffYoung]

Here are a couple of front-end PSUs I drew up. The first is an adaptation of a Jam Somasundram cMultiplier, while the second is an adaptation of a Pete Millet shunt regulator.

My BA incarnation runs at 50V with a 13mA CCS for the LTP and a 35mA CCS for the VAS. They make up the bulk of the front-end load which varies from 51mA to 57mA.

The cMultiplier has much lower ripple and runs cooler. The shunt regulator has better immunity to load variation.

 

[aspringv]

There's a schematic for a pass front end somewhere that's basically a voltage doubler, followed by a reg that's not wildly different to the Mr evil cap multi (just clamped to a voltage).

 

[Itsmee]

I'd recommend ZM's Shunty, or the store Super Reg. I built a shunt version - F2J(ish) CC, TIP142/147 for the shunt element.

 

[Zen Mod]

Good Gemini is Shunty's younger brother , not worse even if not such overkill

sch in Iron Pumpkin thread

 

[Itsmee]

Lazy ZM 😀
Iron Pumpkin(s) and other smaller vegetable animals

 

[JeffYoung]

Wow, it'll take me a while to get my head around that. 😱

What's the purpose of the LTP? If it's for error correction, doesn't it need a resistor in the red oval to separate the input signal from the output signal for the feedback into the LTP?

 

[Zen Mod]

funny ...... it works as is

 

[JeffYoung]

Is that because that the error is so small that the resistance of the trace is enough to differentiate the signals, or is there something more basic I'm missing?

 

[Zen Mod]

click on CookBook in my sig

 

[JeffYoung]

Got it. The LTP isn't comparing {signal} with {signal+error} but rather {signal} with {reference}, where the reference is generated by the JFET CCS and the zener.

(Nice CookBook, by the way. I had only read the thread before....)