BBD clock driver Vgg? (MN3101 / MN3102)

low_rider · Joined: Dec 14, 2011 Posts: 14 Location: Israel

I just got a hold of a few new production MN3102 BBD clock drivers from Cool Audio (they call them V3102). They seem to be the same as the Panasonic ICs. Anyway, the pin-out is the same and from the short datasheet I could figure out what goes where. One thing that is not clear to me is the function of PIN8, marked Vgg. I measured it using a DVM and it shows about 4.96V when the voltage drop on the IC supplies is 5.01V.
I saw this goes to the BBDs, but what advantage does it have over my power supply?

Datasheet:
http://www.coolaudio.com/docs/datasheet/V3102_DATASHEET.pdf

Uncle Krunkus · Posted: Thu Feb 23, 2012 1:27 pm Post subject:

I don't think it's critical which one you use as ground, unless you have more than one BBD&CLK setup in the one unit. Then it helps control heterodyning (unwanted syncing up) of the two Clocks.

low_rider · Joined: Dec 14, 2011 Posts: 14 Location: Israel

Clack · Posted: Fri Feb 24, 2012 4:04 am Post subject:

Hey,

If you look at the original datasheet

experimentalistsanonymous.com/diy/Datasheets/MN3102.pdf

it says it gives out 14/15ths the supply voltage to power the BBD
there muse be some reason for this but I do not know why.

if you look at the "Zombie Chorus" by J. Hollis they use a resistor to lower the voltage as the 3102 is not in use. I have no idea how that was worked out, possibly manually with a multimeter?

http://www.hollis.co.uk/john/zombie.jpg

low_rider · Joined: Dec 14, 2011 Posts: 14 Location: Israel

Clack · Posted: Fri Feb 24, 2012 9:07 am Post subject:

well I guess it suggests that the BBD needs to run off a slightly lower voltage than the Clock.

If you look at the schematic Vgg goes into the Gate of a JFET in between each stage, I am just guessing here but maybe its to control the charging speed of the capacitors in the BBD?

low_rider · Joined: Dec 14, 2011 Posts: 14 Location: Israel

I'm hijacking my own post here... Wink

So I put everything on a breadboard and I'm trying to get an idea about how to work with these ICs. The Cool Audio datasheet is almost worthless I'm afraid. I hooked up an input of a triangle wave biased with a little DC so it will be all positive wave. I hooked up the clock(s) and Vgg. How do I use the inputs? I can see a DC voltage on them but nothing else...