DIYstompboxes.com

Howdy Folks!

      I am building a digital volume control using a DS1669, which I just received from Future Electric.
The input voltage calls for +5 to +8 vdc .   I have an ultra power supply I built that has 9volts output.  What value resistor and wattage should I use to reduce the 9 volts to 6 volts?   

Thank you for your help!
Arn C.

I'm not sure that using just a resistor & cap will do, because the current (from a brief glance at the data sheet) seems to vary from practically zero to 2mA.
So I'd be thinking of a 6v zener, fed from a 1.0 K resistor.
Or use an adjustable regulator, set to 6V, you have enough headroom (but that would be overkill, I admit).
And check out the application notes on the Dallas website..

Thanks Paul !!!! :icon_biggrin:

Peace!
Arn C.

I'd pop in an LM78L05

I ended up putting in an LM78L05.   I will test it out tonight at home to see how it works.  It is a digital volume pedal with 64 steps up and down.  I will still have my passive morley volume pedal inline set for max volume level that I want.  This way I can go up or down in volume incrementally, since I seem to have a problem raising and lowering volume slowly while playing.

Thanks folks for your help!

Peace!
Arn C.

series-diodes can be used to drop volts...
(~0.7V per 1N4148; ~2V per LED...)

Well, I tried it out and NADA, NOTHING, ZILCH, etc...

I will have to check it out tomorrow.  It may be my 9vdc power block connector, not matching up with the connector I put in the box.   so many could be this or that.  Back to the drawing board! :icon_sad:

Peace!
Arn C.

how do you "control" (address) that chippy?

 :icon_confused:

I suspect by your reply I am leaving something 'important' out of this circuit, that I probably no nothing about. :icon_confused:

I can take it!

Peace!
Arn C.

Quote from: A.S.P. on October 03, 2005, 06:44:23 PM
how do you "control" (address) that chippy?

http://www.maxim-ic.com/appnotes.cfm/appnote_number/168 reveals all.
You don't need a micro or anything, there is a "button" mode, where you just have an up & down button.
I thnk this is a perfect app for two 'reflection' sensing IR optical switches, but that's just me. I'm sure traditional stomp switches would be too clunky, though.

http://www.electronics-lab.com/projects/audio/033/

The above is what I used.  I guess I must be missing something.  That circuit is what I built and used 5voltsdc regulated with an LM78L05 and I get nothing.  I did miss where it said to use a dual polarity power supply to cure clipping problems(I didn't do this).
There must be more to this, but I don't know what it is.  I used two N.O. momentary stomp switches.
I'm Lost.............

Arn C.

what`s the suffix # of your DS1669?
if it`s "10", and you hooked your guitar directly to it,
it is loaded by a parallell R of 10k...

Yes, it is "10".  So, does this mean that the signal is loaded down to the point where the signal won't go through?  If so, is there a remedy for this?

Thanks!
Arn C.

not that nothing goes thru,
but that there`s nothing left right up front, to be divided down.

in this case you need a buffer in front of the digi-pot;
or hook the pot after your first pedal in the chain.

you can test the functioning of the pot itself, by hooking a cd-player or the like to it.

So, are you basically saying that I need the signal to be boosted before it goes into the digital volume pot box?

Thanks!
Arn C.

not neccessarily boosted, but buffered


the status quo you got now,
is having the guitar going into a 10k pot...
(as opposed to 1M or 470k usual impedance of amps/FX)

So, if I build a small buffer circuit, I am sure there are some around here, and place that in the beginning of the audio signal then into the ds1669 chip, it should work?

Thanks a bunch for your help on this.
Arn C.

yes

Thanks A.S.P. for your help!  I will give it a try...

Arn C.

"IF" I get clicking when I depress either switch, how could I eliminate that?

I built the buffer from GGG, the transistor one.  I won't be able to try this until I get home this afternoon.

Thanks,
Arn C.

I added a buffer circuit from GGG site to the front end of this DS1669-10 digital volume circuit and the results were the same, no sound at all.   I am stumped.  I did bring my power supply to work with me so I can test it here.   Any suggestions would be appreciated!

Thanks!
Arn C.

I can't suggest anything, except to say that the loading of the guitar wouldn't have stopped the signal alltogether, so there must be a problem in wiring. Check the voltages on each pin of the attenuator chip & see whether they are what they should be.

Thanks Paul, I will do that!  Here is the circuit I have up to date.  Maybe something is wrong with the circuit?

(http://img.photobucket.com/albums/v482/arnc/digivolume.jpg)

Thanks!
Arn C.

I made a mistake in my wiring.  I had the +9 vdc going to R2 instead of R3. Fixed.
I tried it here at work, all I got was a bunch of noise when it should of been a radio station tune.
Still confused.  I will try it at home with my guitar and amp, but I don't expect that it will work.  Without anything (a signal) hooked up, just power to box, I only had voltage on the voltage input pin #8 and
pin #7, both had 5vdc, when I pressed one of the switches, can't remember which one, I think the one attached to switch off of pin #7, the voltage decreased down to almost zero and when I stopped hitting the switch it jumped back up to 5vdc, it wouldn't stay.   I did notice on the data sheet that the input volts to the ds1669 is supposed to be "floating" on power up?  What does that mean?

Thanks!
Arn C.

Okay, after I tried it out in my office and just got noise and no proper sound, I decided for the heck of it to swap out the IC, since I had the power going to the wrong place in the circuit. 
Voila!  It works great!  I took it home last night expecting it not to work at all and it did work.
The only thing I had wrong was which switch was volume up and which switch was volume down.  And of course this is just a preference thing.  I like volume up on the right and volume down on the left.  I will switch that this morning.  And the switches themselve click real loud, not over my amp, just the switches, so I am going to replace them with not so noisy of switches.  The unit is absolutely quiet, It even quieted down my tube amp a bit, I guess because of the buffer in front of it.?  I will post a few pics next.

The next thing I am going to do is to put in a digital readout that shows where I am at with numbers.
(0-64 counts).

Thanks for all your help gents!

Arn C.

tell us, wether the "old" IC crapped out forever, or if you got it working again, plz.

A.S.P., When I make the next one I will try out the old IC and see if it works!

One more thing.  To increase or decrease the volume, all you have to do is to push down on either one of the switches(according to which way you want it to go) and just hold it down until you get the volume where you want it, no multiple hitting of the switch, just hold it!  Sweet!!!!!

Arn C.