tr-505 individual pitch mod + Hex Inverting Schmitt trigger?

[badstatic]

Hello guys, I need a little help from an experienced 'bender' -

I am attempting an 'individual pitch' MOD on my tr-505, using info from Burnkit website -

http://burnkit2600.com/gear/tr-505-pitch-bend-mod/

As is suggested, I am using '40106 Hex Inverting Schmitt trigger' IC to replace the system clocks with variable clocks from the 40106 IC.

I have had some success, although I could only get it to work with a 0.003uf NON polarised CAP (rather than the 0.03uf POLARISED CAP which was suggested).

The mod is working well when I use it to control the pitch of a single drum channel, however I believe that the 40106 can generate 3 clocks per chip.

My problem is that when I repeat the procedure on the next 4 pins of the chip to create an additional system clock, I cannot get a result!

I've checked and re-checked the schematic from the burnkit website, and also the pins on the IC, in case I've soldered to the wrong pins. Still had no luck!

I am using the IC without the transistor, just the 1meg pot + IC + 0.003uf CAP. This is because I want the mod to be permanent.

From what I can tell, I should be able to attach another couple of pots and utilise the other clocks from the IC. That would give me pitch control of another two drum groups on the 505..........?

I am quite a newbee to electronics and I'm almost certainly making a simple mistake here. I'd be really grateful if one of you more knowledgeable guys could take a look at the schematic and tell me where I'm going wrong...

Thanks in advance

Here is a link to the data sheet for my 40106 IC -

http://pdf1.alldatasheet.com/datasheet-pdf/view/22303/STMICROELECTRONICS/HCF40106BEY.html

[badstatic]

Here is a little pic I drew up to show what I've done with the chip so far.



http://i454.photobucket.com/albums/qq264/badstatic/505pitch.jpg

This configuration works fine, but when I repeat the same procedure on the next 4 pins I cannot get a result! I have also tried using a seperate capacitor and again have had no luck......

HELP ME..............

[Uncle Krunkus]

I think the main problem is that you don't have the inputs for the unused gates connected to ground (-ve).
With CMOS chips like the 40106 leaving any inputs unconnected will make the whole chip malfunction. (or not, it's quite unpredictable) So, whatever inputs you're not using must be held low.

[salamanderanagram]

use a bunch of 555s?? probably be almost as easy right, just make sure you keep the voltage low...

[badstatic]

Still can't figure this one out -

Holding the un-used gates low does seem to make a difference, but I'm still having the problem that 'pot A' seems to be interfering with 'pot B'.

SO, using the 40106 , to generate 2 independent ossicilator clocks. Double-invert the signal and feed this into the gate array (after disconnecting the pins from the 505's system clock).

Clock A is controlling pitch for congas, Clock B is controlling pitch for cowbells. . . .
SO why is 'Pot A' controlling both the pitch for the congas AND the cowbells? ?

It is very frustrating. I can't seem to figure out what I'm doing wrong..

Obviously the Gate array pins are TOTALLY disconnected from the 505's system clock.

Any help would be appreciated.

[synthmonger]

add a resistor on either end of the pot, probably in the 100ohm-10k range

[amplex]

[electri-fire]

Hmmyeah... you can make an oscillator with just one inverter/schmitt trigger stage. but with the extra inverter stage in series it SHOULD still work, you used the correct schematic.

So...

The obvbious: check for solder bridges.

easy: maybe the supply voltage ground gets "oscillated".Try an electrolytic capacitor (looks like a small beercan) between VDD (pin 14) and VSS (pin 7). Make sure the marked -side of the capacitor goes to pin7.

More of a hassle: These circuits are very sensitive to picking up stray signals. To illustrate this touch various traces with one of the wires, you'll easily pick up other oscillations somewhere. Just grabbing the wire probably has an influence on the frequency.
Keep wiring as far apart as possible or use shielded cable.


A nice CMOS tutorial:

http://www.fluxmonkey.com/electronoize/40106Oscillator.htm

[amplex]

[electri-fire]

I'm in the process of learning elecronics, so I tend to blurt out stuff without too well established knowledge.

So... please correct me if necessary.

I've seen non polarized capacitors recommended as well, like 0,1 microfarad.

These often look like lentils. A lot less appealing than a beercan I dare say.

[electri-fire]