Orange Squeezer power supply; this will work...right?

[Brossman]

Hey all,

I've finally gotten around to sourcing some JFETs locally, so I can finally BB this dang thing.  After monkeying around, thinking I'm much too stupid to do anything with this, for never being able to get a thing to make sound on my BB, Eureka! at last! (a 10k trimmer I had was bad...never would've thought...)

I decided to junk the whole 10k (trimmer) to ground from the Fets anyhow, cuz it didnt seem to make a whole lot of difference to me.  I'd love to know I'm wrong before I finalize and PERF it.

As for the P/S, I have decided to take advantage of some spare goods (no not half-dead 9v batteries).  I have a 110VAC->9VAC tranny rated at 300mA.  I figured at 123VAC from my Wall socket at home, I will actually get about 10.064V before rectifying to DC.  SOOO, I made a bridge out of four salvaged 3A diodes before I was told that that will increase my VDC by a factor of sqrt^2 (~1.414), which would give me roughly 14.23VDC.  (EDIT: I initially thought Full-wave and Bridge did the same thing. essentially, yes, but no as well  )Adding in a 4700uF, 35V cap across the bridge for ripple filtering, and no load resistor (the OS will serve this function well enough, I figure...).

The only problem I foresee is that the B+ of the RC4558D, according to the datasheet, is 15V MAX.  I suppose I might lose some V from my calculations, but I might in fact also gain some.  I'm just worried about frying the chip.  As for the FETs, they're 35V/40V Max, so I think they'll be just peachy.

No, I will not just use batteries - I plan for this to either be on, or not in use at all (much like a Rangemaster sitting on top of an amp).  No, I do not want to place an online order for a power regulator/power supply/anything else.

I guess my question is more rooted in an EE standpoint.  Is my math sound?  And is my logic also?  Will I fry my chip?  Or should I have some kind of protection on the B+ input (pin ?

Thanks in advance,

- BR

[anchovie]

Maximum power supply rating for a 4558 is +/-18V, which actually gives you a limit of 36V between V+ and ground.

[Brossman]

great to know! must've misread that datasheet...

I'll try to get back to this build when I can get back to a computer... As for now, I'll stick with my misbiased everything... sounds pretty good. 

@Mark, Gus, RG; I've read that I should be getting between +1.5 <-> +1.7V of the gate of FET #1 to the Source of FET #2. However, even with the trimmer turned all the way down, I still only see +2.44V at the lowest...?  BUT that's with a fresh 9v battery.

thoughts?