Relay switching with a positive ground Fuzz Face?

[albinalbinj]

Hi,
I'm thinking about building a Fuzz Face with a relay bypass. I will use the Latching Relay circuit from PedalPCB. Can this be a problem? Can the 555 introduce noise or make the Fuzz oscillate?

Also, can the 555 be substituted with a 7555? Is this a good/bad swap?

Thanks

 

[Stickman393]

I'd recommend using a voltage inverter to do this.

That way, you've got bipolar power supply. Positive ground side feeds the fuzz face, negative ground feeds the relay bypass.

CHARGE PUMP BI-POLAR OUTPUT RTS PCB

The ready-to-solder PCB for the 9v-9v Bipolar power Charge Pump. The PCB dimensions are 3.3cm by 2.0cm. PCB has solder mask, plate-through holes and screen print for placement of components. Click here for complete instructions for this PCB.

store.generalguitargadgets.com

That's a pretty simple one right there.

 

[albinalbinj]

I'd recommend using a voltage inverter to do this.

That way, you've got bipolar power supply. Positive ground side feeds the fuzz face, negative ground feeds the relay bypass.

CHARGE PUMP BI-POLAR OUTPUT RTS PCB

The ready-to-solder PCB for the 9v-9v Bipolar power Charge Pump. The PCB dimensions are 3.3cm by 2.0cm. PCB has solder mask, plate-through holes and screen print for placement of components. Click here for complete instructions for this PCB.

store.generalguitargadgets.com

That's a pretty simple one right there.

Thank you! I forgot to add in the OP that I’m planning on using an LT1054 to invert the voltage, but do you think it will work without any issues? I don’t think I’ve ever seen a fuzz with relay bypass

 

[Stickman393]

I can't say I've seen a fuzz with a relay bypass either, but thats likely due more to the fact that...well...

A fuzz was one of the first guitar effects ever produced: the fuzz face in particular. It's also a circuit that, looking back, had some design choices that folks today likely wouldn't have made. That said, it was used on a ton of recordings and has developed a certain mystique, so much so that certain folks will pay top dollar for versions with all the correct "mojo" components.

Relays are like...what's that? That's not in a fuzz face. *Throws holy water*.THE POWER OF CHRIST COMPELS YOU.

My understanding is, if you're already using a charge pump to invert the voltage, there's no harm in adding a relay bypass on the negative ground side.

The problem arises when one tries to use a unipolar power supply to feed both positive and negative ground circuits. Voltage is a difference in electrical "pressure", and "ground" is just a (largely arbitrary) reference point.

We generally want ground to be, for lack of a better word, "solid". Unmoving. Using both ends of a unipolar power supply for "ground" works against that purpose, and the result is noise.

By creating a bipolar power supply, you now have two separate power supplies, opposite each other, with a common ground at their center point. You can use the resulting power supply as a unipolar 18vdc, or as a bipolar 9vdc.

 

[albinalbinj]

I can't say I've seen a fuzz with a relay bypass either, but thats likely due more to the fact that...well...

A fuzz was one of the first guitar effects ever produced: the fuzz face in particular. It's also a circuit that, looking back, had some design choices that folks today likely wouldn't have made. That said, it was used on a ton of recordings and has developed a certain mystique, so much so that certain folks will pay top dollar for versions with all the correct "mojo" components.

Relays are like...what's that? That's not in a fuzz face. *Throws holy water*.THE POWER OF CHRIST COMPELS YOU.

My understanding is, if you're already using a charge pump to invert the voltage, there's no harm in adding a relay bypass on the negative ground side.

The problem arises when one tries to use a unipolar power supply to feed both positive and negative ground circuits. Voltage is a difference in electrical "pressure", and "ground" is just a (largely arbitrary) reference point.

We generally want ground to be, for lack of a better word, "solid". Unmoving. Using both ends of a unipolar power supply for "ground" works against that purpose, and the result is noise.

By creating a bipolar power supply, you now have two separate power supplies, opposite each other, with a common ground at their center point. You can use the resulting power supply as a unipolar 18vdc, or as a bipolar 9vdc.

That's very true, down to the fact that the "holy grail" of power in Fuzz Faces is a brownstone battery. That's a far cry from a relay bypass. I think I'll try to do a relay bypass Fuzz. I mean, it's a nice feeling, it's more reliable and I don't feel like chasing the dragon of 100000% authenticity, especially when the authenticity comes with hassles such as always having a screwdriver and a fresh brownstone battery for every gig, as well as the fact that the 3PDT has a high failure rate. The relay bypass might not be the most vintage correct, but it is nice.

My plan is to have a ground, a +9V and a -9V, with the ground plane in the PCB, and connecting all the other stuff in the correct way. It might not be "100% vintage correct", but it will hopefully be "100% usage correct".