Dig Dug

[insomniac2295]

I'm starting to build the Dig Dug and I'm just starting this thread as a general Q & A spot for me, as I know I will have difficulty with this.

My first query: Do the 8 LEDs in a row have to be wired up in order for the circuit to work?

[bigmufffuzzwizz]

Judging by the schem it appears like you'd have a bunch of opens if you didn't include the LED's. They aren't set up like a normal bypass indicator wired straight to ground.

[k.rock!]

Yeah, it will work, but you need to short the pads together in order to continue with the circuit. If you leave them out, it will create open circuits like Magic said, and your pots will not work.


-Kaleb

[insomniac2295]

mkay so I popped the LEDs in this morning. Still have no wah. I have bypass alright, but when I touch my audio probe to 6 out of the 8 LEDs all I get is this loud square wave sputtering. The other two have no sound when probed. Any ideas?
I'll post IC readings soonish

[insomniac2295]

For IC1 (TL072P) I used TL072PC
For IC2 (CD4017) I used CD4017BE
For IC3 (CD4093BE) I used CD4093BCN

IC1: TL072PCP
P1 2.85
P2 4.74
P3 4.23
P4 0.00
P5 4.74
P6 4.77
P7 4.85
P8 9.52

IC2: CD4017BE
P1 0.00
P2 ~2.40 (this one jumped around a lot from 2.32-2.40)
P3 ~2.40 (this one jumped around a lot from 2.35-2.40)
P4 ~2.40 (this one jumped around a lot from 2.36-2.40)
P5 0.00
P6 0.00
P7 ~2.40 (this one jumped around a lot from 2.34-2.40)
P8 0.00
P9 0.00
P10 0.00
P11 0.00
P12 9.52
P13 0.00
P14 1.92
P15 0.00
P16 9.52

IC3: CD4093BCN
P1 7.60
P2 7.60
P3 1.92
P4 7.60
P5 8.66
P6 2.85
P7 0.00
P8 ~9.52 (this one jumped around a lot from 0.03-9.52)
P9 ~9.52 (this one jumped around a lot from 0.13-9.52)
P10 ~9.10 (this one jumped around a lot from 0.02-9.10)
P11 ~9.52 (this one jumped around a lot from 0.04-9.52)
P12 0.87
P13 0.87
P14 9.52

[insomniac2295]

For those who are visually inclined:

[insomniac2295]

I reflowed some of the solder on the two LEDs that didn't the came up dead with the audio probe. Now there's no square waveyness on the LED's and sound comes through them. I still can't figure out why I don't have any wah. Do the IC values look alright?

[insomniac2295]

I've seen a couple instances of people having to reverse the LEDs on their board. Should I give this a try? Earlier today, I took out my multimeter, set it to diode, and tested the LEDs to make sure they work. Unexpectedly, when I illuminated one LED, another LED would light up and blink in sequence with the other (like it would in normal operation)

[JakeFuzz]

There should be no audio signal coming through the LED's whatsoever  . This circuit is divided into two sections which are separated and connected by an optoisolator (your vactrol). They are; the filter  and the sequencer. The first behavior you described sounds normal to me, if you attach an audio probe to the LED's you should hear a clicking that changes when you increase the speed knob. It is only going through six because your 4-8-6 switch (or something else) is telling the CD4017 to reset on the sixth step. If the 4-8-6 switch is acting weird check the polarity of the reverse voltage diodes D1, D2 and D4. Also for this test I would temporarily remove the random section (pull the bs170 Q2).

Are the LED's working normally? if not you have a problem with the sequencer circuit and I would troubleshoot that first. The first thing I would do is pull the Vactrol out and put a normal LED in its place just so you can monitor how that is working. Once that LED lights up in time with the sequencer your mission is accomplished. Yes I would also try and reverse one of the sequencer LED's as well, if you cannot get the LED's to light then there is either a problem with your counter or the LFO is not working properly.

If the LED's are lighting normally and you still get no wah then you should move onto the filter part of the circuit. First do the LED in place of the vactrol to make sure it is working properly. If it is then I would plug a variable resistor into your vactrol slot and start troubleshooting with that.

Let us know where you get in these steps and we'll try and track the issue down!

[insomniac2295]

Thanks dude! I'm going to pick up a few parts from my local electronics shop later today and then I'll be busy trying these things out. Great ideas!!!

[insomniac2295]

I have sound through the filter section but everything in the sequencing section just has a really loud pulse kinda like a metronome. Is that normal?

[insomniac2295]

Woah. Just reversed the LED for pot 1. Now the thing works but only for stage 1 of the sequencer. But when stage 1 happens all the LEDs light up instead of just pot 1's LED. I'm going to give reversing the rest of the LEDs a try in a bit.

[insomniac2295]

Good news everyone! It kinda works.... All the LEDs are lighting up in cue, as they should. However, there's a loud ticking when I turn up the tone control. It sounds almost like one of those Newton's cradles. You know with the six or so balls that tick back and forth.
Anyway I don't get it. There's also some background ticking and popping that seems to be going in sync with the sequencer

[JakeFuzz]

Based on your second comment I have a strong feeling your LED's are backwards. Did you reverse all of them or just one? When you reverse one the others still aren't facing the right way so they wont block the current now traveling in that node. This causes them to all light up. They don't all light up when they are all facing the right way because the LED is a diode and wont allow current to pass provided it is faced correctly. Unfortunately this also means that only one of your sequence steps will work because now the backwards LED's are blocking the 5 volts dc coming out of the other 7 counter pins.

If this jives with what you are seeing reverse the rest of the LED's and report back.

As for the noise that is a really common issue with counter based circuits. I have a goatkeeper clone that I still cant seem to keep quiet. If it is too loud though that is indicative of something wrong. Clicking in the audio path means that the isolation between the digital (sequencer) and the analog portion is not good enough. If you can get a hold of a little inductor I would try and put that between the analog and digital grounds. 

[insomniac2295]

Yeah I already flipped around all my LEDs to get then to light up in sequence instead of all at once. My main problem stems from all this background noise but I guess I can live with that. One last thing, though- my pot 8 doesn't seem to be doing anything. I can't seem to control the last step in the 8 sequence at all. It's just always on. Should I audio probe it?