Newbie to Schemos - assistance needed

[wiz1der]

Hello,

I am not new to soldering, but new to schematics. I have a small project for turning a mono keyboard into stereo, and was going to put this together on perf board.

http://groupdiy.twin-x.com/albums/userpics/10028/perf proj.pdf

My question is on the section where the CEM3360 is located, the part where it shows pins 1 through 7. Sorry if it's a seemingly silly question. I do see that this is just repeated for the other half of the chip, pins 8 through 14.


pin 1 goes to what?
pin 2 continues onto pin 2 of tl082
pin 3 connects to pin 4?
pin 4 goes nowhere (to pin 3?)
pin 5 to ground?
pin 6 is connected to left audio bus
pin 7 is connected to -8v

Any other pointers you may have on this to make it go a little easier would be greatly appreciated. Without you guys, or a place like this, I have no idea where i would go for this info. Thanks to all!!

:guinness:

 

[JPK]

pin 1 goes to what?
To Ground

pin 2 continues onto pin 2 of tl082
Yes

pin 3 connects to pin 4?
Yes

pin 4 goes nowhere (to pin 3?)
To Pin 3

pin 5 to ground?
No. Pin 5 goes to Pin 10 and to the node 3u3/10n/2M2/3K3/3K3

pin 6 is connected to left audio bus
Yes

pin 7 is connected to -8v
Yes

 

[alk509]

1 to ground
2 to left TL082
3 to 4
5 to 10 and control voltage
6 to left input
7 to -8V (should be -12V :?)
8 to ground through a 10nF cap
9 to right input
11 to 12
13 to right TL082
14 to +12V

You can download the datasheet for the IC here.

Peace,
Al.

 

[PRR]

> section where the CEM3360 is located, the part where it shows pins 1 through 7. Sorry if it's a seemingly silly question.

It is only "silly" if you know the answer. I've messed a bit with schematics and chips, but I have no clue what pin 3 does.

But I know who should know: the data-sheet. And it happens someone has preserved the datasheet for this rare 20 year old part:

http://www.synthtech.com/cem/c3360pdf.pdf

Comparing your plan against the data-sheet: your plan simplifies the '3360 to a triangle, the sheet shows internal details. This may help understanding. See, the input signal (all your voice-mix resistors) go to pin 6 and 9 just like the sheet shows. Output comes from 2 and 13. A control voltage goes to 5 and 10. A box does a log-thing to it, then you get an external loop to modify the logged control voltage, but in this case you just jumper through 4-3 and 11-12 to get the logged control voltage onto the triangular VCA. (See the last two schematics on the data-sheet for applications that do not use the log-box and need the pin 3 and 12 direct inputs.)

BTW: if you don't need electronic volume control, you could replace the $60 CEM3360 with a $2 (or $15) manual pot. They are not even using the two control inputs to give stereo vibrato ala Fender Rhodes.

Pin 8 needs a small cap to filter the internal reference. Pin 14 needs a positive supply voltage, pin 1 gets a zero-volt supply or reference (ground), and pin 7 needs a negative supply voltage. The sheet shows -12V here, your plan shows -8V. But a "feature" of this chip is that it hardly cares what voltages you feed it. Input and output are normally at near-zero volts, you need about 3V + and - of zero to keep the transistors alive. Maximum total supply from V+ to V- is 25V; above that it melts. I don't know where +12V/-8V comes from, it seems odd, but will work perfectly fine. (Ah: one spec improves slightly if the - supply is lower than 12V. No big deal.) +/-9V, two 9V batteries, will also work fine, though battery life will be about 8 hours.

 

[wiz1der]

You guys are absolutely awesome...

I got straight answers, which i liked. and PRR answer which educates as well as informs.

PRR:

This will be powered from the main pcb in the keyboard. There are 12 and -8v present there.


Thanks for your help. All of you.