Goatkeeper trem.

[JakeFuzz]

We were discussing this over in the requests section a couple of weeks back and I had an interesting idea for how to make one of these. I have purchased a pic programmer and have begun to modify the code to make this work, I have been getting a little help from Tom (the original programmer) as well as Chris Safi over at DIY stompboxes. I was wondering if anyone would be interested in this when I finally get it finished? I am about halfway through the program modification and testing, so far all of the device fundamentals are there. It is finals week so I cannot finish it for a few more weeks, but I plan on making a full working prototype over the Christmas holiday and maybe some accompanying youtube videos (if I can get the code to work). I have already made a layout in Eagle just to see how it would look and it is pretty complicated, I am not the best layout creator so I might need some help with that. 

[madbean]

I'd very much like to see your progress as it develops. I may be able to lend a hand with the layout, if needed.

[JakeFuzz]

Alright, ill keep you guys updated. Thanks for the interest Brian and the offer to help, the layout is a long way off. I want to make sure it all works as planned before I get too far ahead of myself.

So far I have bread boarded the PIC and a CD4017. The setup uses leds on the counter outputs and the actual PIC wave output (because I don't have an oscilloscope). Right now I am just trying to make the pre-multiplier clock output sync up with the base waveform output (PWM output) in both frequency and phase. This is a critical characteristic of the clock output feature and it is proving harder to code than I was expecting.

I have already added x5 and x16 multipliers, and removed the next multiplier input pin code, in its place I have put a post multiplier clock output. This output will trigger the indicator leds for each step of the sequence. Unfortunately at the x16 multiplier very high tempo settings will cause the wave output frequency to exceed the max allowable range and reverts back to a slower speed. This may be a hardware or software limitation which I will look into, but at this speed even the x8 multiplier is too fast for any LDR to respond to.

The sine and triangle shape waves start high (so technically a cosine wave  ) so I thought putting a toggle switch to phase shift the clock outputs (pre and post) by 90 degrees would be a pretty cool feature. Although it will probably be pretty easy to make this change via software it would still be cool to have just to experiment (this would make the multiplier changes happen at the wave centers rather than the ends)

[JakeFuzz]

Oh and Chris Safi is planning on making an 18f chip with essentially a port of the 16f code but with a waveform record function! Just like the new Goatkeepers or the Hollow Earth trem. If he releases that before I finish I will use that code instead.

[culturejam]

Dude. That is so far over my head that I can only say "rock on!" and clap. 

[JakeFuzz]

Code works beautifully!!! Finals finished today and I had a great idea this afternoon to make it work. The downside is that my cool clock invert feature wont work because the clock output isn't a 50% duty cycle wave  . Which just means that I will have to make the triangle and sine waves start low in the code, not a problem. Prototype here we come! If anyone wants the code PM me.

Dude. That is so far over my head that I can only say "rock on!" and clap. 

Nah, it really isn't that bad. I just picked all of this up last week. Everything is very program/application specific which makes it all sound kind of crazy.

[JakeFuzz]

Finally the last parts have come in for this. Ill try and get a barebones test run going later tonight.

[JakeFuzz]

Initial tests are interesting. The sequencer clock input isn't working like it should for some odd reason. The tremolo part works well, but there is a very strange noise when the tremolo signal is high, like a million chirping birds in a tissue box. 

Chip is on breadboard and everything seems to work fine, more tests to come.   

[JakeFuzz]

It works






http://www.youtube.com/watch?v=25txN6dibag

Sorry for the out of tune guitar (too excited to tune) and horrible sound quality, this is only video capture device I own. 70's strat with Dimarzio Area pickups and a Twin Teverb RI.

There is some small clicking when the trem signals trigger, but that is expected. No LED's because I haven't made the attachment flange yet.

[stecykmi]

this is sweet. I didn't think something like the goatkeeper would be cloneable.

any plans on releasing schems and source code? 

[crashguitar]

Very impressive!
Now get work on reverse engineering all the Strymon stuff. 

[maysink]

Wow. Just wow.

[JakeFuzz]

this is sweet. I didn't think something like the goatkeeper would be cloneable.

any plans on releasing schems and source code? 

Source code is available to anyone who wants it. I cannot take credit for 90% of it. I really just added an extra algorithm to suite the needs of this pedal. Is there a file sharing site I should post this to so everyone can have it?

As for schematics, the schematics I used to generated the layout are very rough and not intended for readability. I am posting the rough layout I used but the sequencer board doesn't have any of the ins or outs labeled.

I am not going to lie, this project needs lots of work if other people are going to start making it. The layout needs to shrink a great deal. A volume control needs to be added to the trem circuit and losses over the reverse voltage protection diodes need to somehow be accounted for. My next few weeks are going to be crazy so I don't know when Ill be able to finish this up. Ill try and post a decent schematic before anything else so someone else can fiddle with it.

[JakeFuzz]

Very impressive!
Now get work on reverse engineering all the Strymon stuff. 

I wish I had time (and money) to get some of those worked out. One of the projects I was hoping to get started next was to make a small footprint real tape delay using the old Walkman style cassette read/write heads and tape cartridges... One day.

[NoizeD]

Impressive indeeed! I'd quote crashguitar but iguess you don't have that much time Great job