Vibrochamp - choke?

[matt h]

(deleted)

[angelodp]

Matt, are you a fan of the VibroChamp? Any changes you have made to this icon?? RJ hit a home run with his version of the Champ.

[matt h]

(deleted)

[martin manning]

Another thing to keep in mind, and this can't be ignored, is that inductance of a choke varies by the amount of current drawn through it. So if I'm glancing at that spec sheet right, this thing is rated for 300mA (.3A). The available inductance at lower current draw will be higher. How much? I won't guess. It will be higher, nonetheless.

I believe inductance will remain essentially constant until the current is sufficient to cause core saturation, at which point the inductance will drop.

[matt h]

(deleted).

[martin manning]

Hmm. Measuring the inductance of power supply chokes at very low current using an LCR meter I get values close to spec, so I don't know what to make of the data overtone posted. For example, a Hammond 15H 75mA choke I have here measures 13.1H at 50 uA (rms, as determined by a current sense resistor, no DC). A little low, but within the 15% tolerance given by the manufacturer.

[Structo]

Man, $65 for a choke?

[tele_player]

Man, $65 for a choke?

Seems crazy to me, but so does $45-$50 for their standard single-value chokes.

-robert

[angelodp]

Ok, she's up and running and sounds pretty good with the extra large PT & OT on this doner amp. All is well and there is that usual SE hum, although not out of the ordinary. I am going to implement some of the fine suggestions you have supplied. I tweaked the layout to show, but I am confused on the placement of the OT line to ' the second node' . This PT does have a ground reference for the heater voltage, I am showing the .1uf cap now in line with that ground. I assume a non electrolytic is the way to go.

On a side note, when I fired up the amp ( after bulb limiter etc ), the amp did not produce sound? Voltage seemed fine. It turned out to be the 12ax7 socket on V1 was oxidized ( had not been used in a great while ). After jiggling the V1 tube it came alive.

Another side not. This OT has a spare output with low voltage that I have used on another similar doner to create a NFB loop. Question: you reckon a variable pot for NFB will be useful on a VC?

Is the choke placement looking correct?

Thanks for the feedback guys.

FLASH - hang on - I just took the heater ground to the 6V6 cathode 470r/3w - 25uf junction - Done - as in the Eagle project - I simply forgot to look back at that project. Its reduced hum significantly and I doubt I'll need to pursue the choke for now.

[IMG880]http://i260.photobucket.com/albums/ii9/angelodp1/VibroChamp-1801-choke_zps6de3de31.jpg[/img]

[brewdude]

MM has this cool idea.
http://www.mercurymagnetics.com/pages/c ... ichoke.htm

So if I'm glancing at that spec sheet right, this thing is rated for 300mA (.3A).

Where did you find the spec sheet?
I can't find any thing that gives any indication of mA ratings.

[matt h]

(deleted)

[angelodp]

Looks like 3AD.C. with .025 H - in any case I am not going to go the Choke route for now as the build is pretty quiet. Might revisit at some pint

Thanks for the input.

A