Can the Orange Squeazer be set up for 18vdc operation?

[lowvolt]

Can the Orange Squeazer be set up for 18vdc operation?  Is it simply a matter of using caps with a high enough voltage rating (50v + or so)?  Or are the jfets/IC not happy with that much voltage?

Thanks ..

[R.G.]

Probably. What are you trying to achieve by doing this?

[lowvolt]

Use an 18volt psu that's on my pedalboard, some stuff is daisey-chained.  It's a curiosity thing as well. 

[R.G.]

Fair enough.

The reason I asked about objectives was to find out if you expected it to handle different signal sizes than it already does, and to find out whether "easy and fast to do" was in the mix for you.

The simplest, quickest, easiest-to-get-running way to do this is to put a 78L09 on the OS board that will take in 18V and make 9V for the circuit to use as is. This needs zero changes to the existing and presumably well-functioning circuit to get done; only a couple of non-critical parts and some wiring. I'd put this approach under the "works with my existing 18V output" objective.

The complicated way is to go mucking about inside the circuitry, messing with the biasing and the JFET setup to get it to work at 18V. I'd put this under the curiousity objective.

[lowvolt]

So, does that mean that using caps of a higher voltage than the 16v Tants (let's say 50v Al Els) won't work with 18vdc input?

[R O Tiree]

The JFET biasing will not be affected very much at all by running the pedal at 18V, but it should be easy enough to adjust. One of the JFETs is wired as a current source so, theoretically, the voltage at its Drain should stay rock-steady with varying supply voltage. In the non-theoretical "real-world", you might find that you need a little tweak of the trim pot to fine-tune the sweet spot.

If one of your electrolytics is being used for power supply filtering, then I'd definitely replace it. All the others are sitting comfortably within the 16V rating you have observed while the circuit is running. That said, it takes about half a second or so for the voltages to settle down after the pedal is switched on, and it cannot be guaranteed that some of them won't see voltage spikes close to the supply voltage during that dynamic "start-up" process. Just to be on the safe side, I'd replace them all with ones rated at >18V throughout.

If you are, as RG asked, looking to run bigger signals through it, then you're out of luck... This design of compressor has a kind of "cross-over" voltage, at which Signal In = Signal Out. Below that level, the signal is amplified. Above that level, the signal is attenuated (the output still rises as input rises, but at a gain less than 1). This cross-over point is totally dependent upon the other JFET's V_GS and R_DS characteristics.

[lowvolt]

The JFET biasing will not be affected very much at all by running the pedal at 18V, but it should be easy enough to adjust. One of the JFETs is wired as a current source so, theoretically, the voltage at its Drain should stay rock-steady with varying supply voltage. In the non-theoretical "real-world", you might find that you need a little tweak of the trim pot to fine-tune the sweet spot.

If one of your electrolytics is being used for power supply filtering, then I'd definitely replace it. All the others are sitting comfortably within the 16V rating you have observed while the circuit is running. That said, it takes about half a second or so for the voltages to settle down after the pedal is switched on, and it cannot be guaranteed that some of them won't see voltage spikes close to the supply voltage during that dynamic "start-up" process. Just to be on the safe side, I'd replace them all with ones rated at >18V throughout.

If you are, as RG asked, looking to run bigger signals through it, then you're out of luck... This design of compressor has a kind of "cross-over" voltage, at which Signal In = Signal Out. Below that level, the signal is amplified. Above that level, the signal is attenuated (the output still rises as input rises, but at a gain less than 1). This cross-over point is totally dependent upon the other JFET's V_GS and R_DS characteristics.

Nope, not looking for more headroom or anything "magical" out of 18v operation  It's more of a matter of convenience on my pedalboard.

TOTALLY big-thanks for the reply here.  I really wasn't in the mood for re-inventing the wheel just to make it run at 18vdc.  I'm already using all 50vdc+ caps so I think I'm good to go.  And thanks for the deep-dive-dirt on the workings.  I'm still trying to brain-up on jfet matching and learning more about biasing and such.  Up until recently I've been more into opamp based amplifiers, so this whole world of fets and transistors is new territory for me.  I've yet to construct an HFE tester, so you can see how far I am behind.

I'm only just now getting into fuzz circuits as well.  The horror ....... the horror. 

Thank you once again.