Finished My Crash Sync in Hammond 1590B

[Paul Marossy]

I just finished wiring up John Hollis' Crash Sync into a Hammon 1590B using the PCB layout at his website. Man, it's tough to get all that stuff in a little box like that, but I found a way to get it all in there. I'll post some pictures of it in a day or two after I'm done painting it and stuff. 

[markm]

Air-Brush again Paul? 

[Eric H]

How does it sound?   

-Eric

[Paul Marossy]

No airbrush. Sounds pretty cool! Better than the one soundclip that I've heard. Anyhow, here's a few pics of it. This is another enclosure that was given to me by a co-worker. It used to have some kind of electrnics in it, but I don't know what. It was a challenge getting all of that to fit in there! Whew.

I hand painted the lettering and stuff. Not a Z. Vex box, but I think it came out OK. That LED also serves to hild the PCB in place. A happy accident...

[bluesdevil]

Good job!! Reminds me of those Colorsound Tonebenders!!!

[Paul Marossy]

Thanks bluesdevil. I didn't consciously think of those ColorSound pedals when I was making it, but now that you mention it, it does look like one of those. 

[$uperpuma]

hand painted is cool.... I guess this one will be on my long list....

[Paul Marossy]

hand painted is cool.... I guess this one will be on my long list....

Yeah, I was thinking about a comic book kind of theme when I was painting it. I like it. It even can get this neat octave down sound depending on how you set the 100K pot that's between pins 6 & 7 on the 555.

[Paul Marossy]

I forgot to mention that I used 0.1uF caps instead of the .047uF caps specified on the schematic. I think that makes it sound a little "thicker". 

[jmusser]

Paul, I was wondering if your's has a nice octave down feature to it? This was something that was never eluded to, and is not on the sound samples, but if you adjust the timer pot to the sweet spot, it's probably as good as the Shoctave. I haven't had mine out for awhile, but that's what I remember. I was wondering, if this was just sort of freak feature that mine alone had, or whether they all had it.

[Paul Marossy]

Paul, I was wondering if your's has a nice octave down feature to it? This was something that was never eluded to, and is not on the sound samples, but if you adjust the timer pot to the sweet spot, it's probably as good as the Shoctave.

Yep, it does as a matter of fact. I can get that with the timer/freq knob turned full clockwise. That's too bad it's kind of a secret about the octave down thing, I bet more people would build it if they knew about that.

I haven't had mine out for awhile, but that's what I remember. I was wondering, if this was ust sort of freak feature that mine alone had, or whether they all had it.

They must all have this feature if mine does the same thing.

[birt]

looks very nice. but it isn't too big if you leave out the battery :p

i don't really understand why you would want a battery, those things are expensive, especially if you like to use leds as much as i do

[Paul Marossy]

looks very nice. but it isn't too big if you leave out the battery

Yeah, I know.

i don't really understand why you would want a battery, those things are expensive, especially if you like to use leds as much as i do

I agree, batteries are too expensive and I don't like the idea of those things piling up in landfills, it's just wasteful to me. In any case, 98% of the time, I don't use batteries - I just have a DC jack. In this case, I thought it would be fun to challenge myself on this build.

[birt]

i'm with you on the challenge thing. i allways try to cram loads of stuff in way too small boxes just to know i CAN 

[Paul Marossy]

i allways try to cram loads of stuff in way too small boxes just to know i CAN

Yeah, I hear ya. Must be a guy thing, you know, to conquer. 

You know, this circuit is pretty nifty the more I look at the schematic. That 555 is operating in astable mode as an audio oscillator - operating apparently at a frequency above the audio band, by continuously resetting itself every cycle (pins 6 & 2 connected together). When the guitar signal goes to pin 4, it resets the oscillator to match the guitar frequency(ies). As long as the guitar is sending out a signal, that oscillator will continue running at the same frequency(ies). So, if your guitar sustains well, it will go on for quite a long time. Interesting concept that I assume originated with the early monophonic synthesizers.

The part I don't get is how octaves are generated. Must be something to do with the design of the chip, I guess. I'm guessing that it somehow rectifies the waveform. 

I think I'm going to scope it when I get home tonight. I'm very interested to see what's happening to those waveforms!

[Paul Marossy]

I'm frustrated this morning because my scope needs to be recalibrated a little bit and I stayed up late messing around with it... but anyhow, I put it on the scope last night. I fed the input a 440Hz sine wave to start with. When the octave down sound starts to appear, it was showing a square-ish wave modest pulse width modulation at the output. Not quite what I expected in terms of the waveform, but nonetheless interesting... 

[jmusser]

That might be a good question for R.G., since he seems to have a pretty good handle on the Hollis circuits, and what makes them tick.

[Paul Marossy]

Yeah, RG would probably know - he seems to know everything! 

In the morning, I'm going to scope it again with my freshly recalibrated scope. Man, what a pain to adjust all that stuff in an analog scope.