Does anyone have a schematic for a very basic soft start phantom

[zmorrow]

Looking to build a basic soft start phantom power circuit that utilizes only caps and resistors. any thoughts? and yes i know this is basic.

[ulysses]

You need a transistor. Otherwise, your soft-start circuit (RC filter) will also serve as a current limiter. Which you already have in the form of your phantom buildout resistors. If you need a softer start than that, you need an active device. Or I suppose you could use an NTC thermistor.

[zmorrow]

ok got it i was afraid that was the case thanks ull

[ripple_fx1]

Elliot Sound Products has a PCB....JR

[ulysses]

In fact, scratch the NTC thermistor. You don't have enough current to reliably bring it to a low-resistance state.

But really, an active circuit isn't terribly complicated. It's something you could easily build on an arbitrarily small breadboard. I'm too lazy to go make you a schematic and upload it here, but google ought to get you there quickly.

Here's an example, though you really only need about 4 of these components to use with your existing 48V supply.

DIY Factory - soft start phantom

[2N1305]

Indeed.

Just how basic would you like it to be?

With about six components, you could have a nice customizable start-up time circuit that only drops off about 0.6V from the 48V supply...

[nosebleedaudio]

Can be done with a cap and resistor for a short soft start, but still far better than not one...
Most mics only draw around 4ma or less. adding a small amount in series with those 6.8K will not change much...

[zmorrow]

Thanks guys,
I got a stable circuit running as we speak with adjustable ramp on and off.
it also is running off 345 volts dc!!!!! (tube power) with protection and load of 17.47 ma which is the max phantom load.
been holding steady for about 6 hours now.

but had to use transistor dam!!

[Dan Kennedy]

Yeah, be careful, that solid state shit will suck you in.

I remember, back, oh hell it might have been '68 or '69, I was eased on
over to the dark side.

12AX7's weren't quite as available in the TV sets I was scavenging for parts as
they used to be, but the transistorized garbage was coming in.

Never looked back, but beware, the 21st century will come along soon enough
and whack you on the back of your head!

Oh lord, where is thy vacuum?


sorry, just an old fart bitchin'

[zmorrow]

no dan i agree!

i hate transistors with the exception off the 2520's ops

i didn't want to use em but i don't have enough space in the boxes for an 0ar2 reg and all the other tubes i'd have to use so unfortunately i'll be using 2 trans and a reg chip.

however it will be rectified by a 5y3