Pulp Squeezer

[JohnH]

Very nice and tidy. Sorry you had so much trouble with the decal though

[jugglindan]

I agree, very tidy! Kudos.

Do you need a bit of insulation between the edge of the board and enclosure? If the board can move at all it's fairly easy to short the traces.

And I feel your decal pain after the struggle I had with the last one. I did look into making silk screens, but was disappointed when I learned that the process permanently sets a screen to one design (or one layer of one design). Great if I wanted to crank out 20 identical pedals, less great for my experimental 1-off designs.

[JohnH]

...but was disappointed when I learned that the process permanently sets a screen to one design (or one layer of one design). Great if I wanted to crank out 20 identical pedals, less great for my experimental 1-off designs.

No, you can strip it off really easily. That's how I picked up all my fabric screens so cheap - the lady who owned them didn't know she could strip them, so once she was done with her shirt run she sold them for $20 each!

The one thing to note though is that the stripping chemical is often tied to the emulsion you use to set the image - different brands don't usually work with each other*. In cbr, you can coat a screen at Megalo for $5, and strip it for $2 (there are other fees too - hire, etc). If you're doing it at home the stripper I use comes as a powder that makes up a huge amount of liquid when mixed. I don't know how much it would be per screen but it would be $1 or less.

I usually do a few pedals at once, so I can get three or four stencils on the one screen, print them all and then strip it.

*Having said that, there is an ultra-caustic process that will strip anything, so if you find a good second hand screen but don't know what they used to put the image on it is still possible to get it off, it's just gross.

[jugglindan]

No, you can strip it off really easily. That's how I picked up all my fabric screens so cheap - the lady who owned them didn't know she could strip them, so once she was done with her shirt run she sold them for $20 each!

Good to know. None of the YouTube videos showing the homemade UV exposure method mentioned that part. But it does look fairly easy to make screens from some pine, mesh and a staple gun. I was thinking something A4 sized would be good for pedals. Also hoping I can do it more cheaply than the kits from Eckersleys by shopping around on eBay.

[JohnH]

Yeah, it's a really common complaint, but definitely a very simple and doable process (easier than getting the image on, in fact)

A4 works fine. I normally try to get a screen a bit bigger, as it makes printing easier, so A3 or so. The one I normally use is 50 x 40cm (from memory), but that just means I can get a few designs on and need a good support/bracket system when printing.

The most important thing is the mesh. Honestly, can't stress it enough. Bad mesh= bad prints, every time. You can get away with an awful frame, but the mesh makes the image. A good 70T yellow mesh will do almost anything you'd need, but if you want small details (small font, or halftones) I'd use 100T like this:

https://gjs.co/supplies/p3371/100t-screen-mesh

[Bakersdozen]

I agree, very tidy! Kudos.

Do you need a bit of insulation between the edge of the board and enclosure? If the board can move at all it's fairly easy to short the traces.

Thanks mate, yeah I will look at that when I get in to do the biasing and make the board a permanent fixture. It's currently sitting in there Blu tacked to the top of a plastic milk bottle for some clearance. Hot glue might be the answer. I just need to get a hot glue gun.

[Bakersdozen]

So I had a little while to have a play with this tonight. Wow, it is such a sensitive circuit in terms of biasing the transistors hey. Initially my thoughts are it is quite hissy when engaged. The sweep of the trim pot is SUPER sensitive. It seems to react differently to single coils and humbuckers in terms of dialling it in. Humbuckers seem to always have a slight edge of breakup thing going on (not always a bad thing) no matter where the trim pot is. But I'd prefer it to be a clear compressed situation. I'm going to play with it a bit more and possibly try some different op-amps / trannies etc. for a little while until it starts speaking to me. A fun little beast of its own though, which is super fun.

[jugglindan]

You could try J201s instead, as I have heard of others using them. Mine is using 2N5457s just fine though.

Did you try hooking a multimeter to the gate lead of Q2, then adjusting the bias trimmer until the voltage to ground is between 1.3 to 1.5 volts? That's the method I used. In my build thread I have a photo showing the voltmeter at 1.314v, but I think I actually went a bit closer to 1.35v the next day. To set this you don't need signal, just have the board powered up.

I get good compression (both limiting peaks and boosting low signals) at that setting with both single coils and humbuckers (the DiMarzio PAF in the G&L).

[Bakersdozen]

You could try J201s instead, as I have heard of others using them. Mine is using 2N5457s just fine though.

Did you try hooking a multimeter to the gate lead of Q2, then adjusting the bias trimmer until the voltage to ground is between 1.3 to 1.5 volts? That's the method I used. In my build thread I have a photo showing the voltmeter at 1.314v, but I think I actually went a bit closer to 1.35v the next day. To set this you don't need signal, just have the board powered up.

I get good compression (both limiting peaks and boosting low signals) at that setting with both single coils and humbuckers (the DiMarzio PAF in the G&L).

TBH I've just been doing it by ear. But I will try that approach and see. That was my next step. I do get better performance if the volume is backed down to around 9.

Do you much background hiss when yours is engaged, but not playing?

[jugglindan]

On my build, volume at 9 is close to unity, so I don't go much above that. Never past 10.

The hiss is typical of a compressor. It's amplifying the noise. This circuit doesn't have a threshold adjustment, and I don't know what level the threshold is. I use a noise gate though, so probably not hearing as much noise.

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