dual tone generator

[ben]

Nevermind this problem of supply i'll do with a battery for this....
Image of my VHS synth inside : DTG / whacky tone control / parallel universe....................

[André]

I'm trying to build this thing and I did'nt thought it would be any problems. But when I plugged in the battery I accidently touched some wrong points and it stopped to produce tones and all that comed out was "scratchy" saounds. I thought that I destroyed something in the 40106 but after a while it started to sound correct again, but no very very low. How do I know if the IC i broken? If I had some more of them I just would have built another but this was my last. Anyone know whats the problem is?

[dnny]

IMO the best way to tell if the IC is broken is by replacing it whit new one - if the circuit works after replacement it was the IC. if not then it´s something else... but i read thet you don´t have any more left ... hmm

are the  both "channels" gone very low on volume? you can try swap the IC´s. or maybe you have malfunction on R2? - measure the potentiometer R2.

is the battery OK?

is one of the IC´s getting hot? your chip may have cancer :

quote from WarantyVoid:
It is important to regard that an IC that once has been overloaded by short circuits, wrong voltages or static electricity can still starve many days or months later even when it seems to have survived without damage. This is caused by small internal short circuits on the silicon die, those can come into being by the "lightning strikes" of static electricity or local overheating from too high currents. These so-called "hot spots" make the chip draw more current and make its silicon locally overheat again. The local overheat softens the different layers of the chip and thus makes them slowly melt together (electro- migration) , which enlarges the heat producing short circuit area. At the beginning such a chip can still behave normal and only run hotter, but when such an area of "chip cancer" has grown large enough, it will make the chip fail. Very typical for chip cancer is that such a chip still works perfectly for some seconds up to many minutes, but always makes mess after the device has fully heated up. While at the beginning the problem only occurs after a long time under hot conditions, it will later often happen after few seconds when the chip is finally fried "well done".

Chip cancer can not be undone again; only a sufficiently big external heat sink (optionally with fan) and possibly a reduced supply voltage may make such a chip behave normal and possibly stop the progress of the cancer so far the hot spot is cooled down well enough and is not too severe yet. Thus for prevention of chip cancer it is crucial to regard safety measures against static electricity, not to apply wrong voltages (especially no reversed polarity) and better not to short output pins for long time, even when a chip seems to survive the latter without noticeable damage.

HTH
daniel

[ben]

Let's talk again about this stuff i "discover".

A friend of mine got a Serge synth and i want to built for him a Dual tone generator with a CV output how could i do that.

I don't really know what CV means and i can't test it because i don't have any synth with those kind of output.
Is it possible ?

[expanoncolin]

Let's talk again about this stuff i "discover".

A friend of mine got a Serge synth and i want to built for him a Dual tone generator with a CV output how could i do that.

I don't really know what CV means and i can't test it because i don't have any synth with those kind of output.
Is it possible ?

Well, in the end it depends on whether he wants a 1V/octave scaled VCO, or just a simple oscillator that has a voltage control.  You've worked with vactrols, right?  All that voltage control implies is that the frequency is somehow related to a voltage on some input, that is, more voltage on the input means a higher frequency-so if you wire a vactrol up, you can create a dirty CV-in whose resistance raises or lowers depending on the voltage input.  Though in the synth world, a CV controlled tone generator often implies that the VCO has some sort of scaling, most commonly, 1V increasing meanting 1 octave increase.

Hopefully BugBrand can comment-he's done a lot of work with creating oscillators that have CV ins but aren't necessarily scaled.

-Colin

[ben]

I think he wants a a simple VCO OUTPUT.
I don't understand what you mean about vactrols. I just wanna change the output signal into a VC outputwitch could be plug into an input of the serge...

I've found something once (but don't remember where on the net). It was a circuit witch helps inserting a stomp box into a modular synth. Maybe such a technic could help me to turn the output of my DTG into a VCO....

Or maybe i'm just a idiot    because it's impossible.

[expanoncolin]

Oh, I thought you wanted to voltage control your dual tone generator.

You could use the dual tone generator output straight away as a control voltage.  The output is probably something like 2-7V, synth control signals are oftem -5V - +5V.  But still, that range would probably be fine as a rough CV.  You could use a bipolar-supplied (+/-15V) offfset amplifier to offset it to about -3.5V - +3.5V, and then amplify.  An oscilloscope would be ideal here-look at what CV signals the serge has, by looking at the LFO, then look at the dual tone generator, then create the appropriate offset amplifier.

-Colin

[haiku-ish]

Hi, first thanks ton ben for his design (and colin for the forum and PU), great sounds out of the 2 tones generator, here is a picture of mine... (2 tone generator + triwave picogenerator+green ringer in the same enclosure.)



see other pictures here : http://http://www.moregeometrico.net/diy.html

best
hk

[ben]

nice what is that box ?

[haiku-ish]

thanks...

an old portable heater.

[ben]

SPOOKY MAN !

[stopmakingsteve]

I just built mine and it's awesome, thanks for the plans.

[chutneyfarmer]

heya, just joined the forum after reading it for a long time.

built one of these last week too. sounds great!!! thanks for the schematics. for my next build i was thinking of combining 2 of these together. possibly so that osc1 from one circuit would ring modulate osc1 of the other circuit. any idea how i would go abut it? or any other ideas of interesting ways to combine 2 together?

thanks in advance

[simonm]

...so that osc1 from one circuit would ring modulate osc1 of the other circuit. any idea how i would go abut it? or any other ideas of interesting ways to combine 2 together?

I've been thinking about this too. Building DTG no2 at the weekend. I think they will sound just great together, with some tremolo and delay, but the
easiest way to combine/modulate them would be w/ a passive ring modulator - one for the input, one for the carrier - just search the forums here - there's a thread in the articles+tutorials subforum and a couple of other threads in the fx subforum. I made one - easy build, but you need germanium diodes, eg IN34A.

[simonm]

I added STARVE pot on the chip power supply on my second DTG and (a 10K pot IIRC) and it makes for a much wider range of great sounds!

lower power = glitchier, dirtier, lower notes, but also raygun/atari beeps and boops, rough tremolo effects etc - try it!

[edit - just moved the subject line into the post - it didn't make sense as it was]