4PDT switch for bypass and on/off?

[Jussi]

Hey,

I heard some pedals do drain battery even if bypass is on if your guitar cable is plugged in. In this layout I've used 4PDT switch to turn the battery of when bypass is on. Would it work at all? Would I hear any sound when bypass is on?

[LucifersTrip]

of course you can use a switch for the battery (instead of the common guitar plug into stereo jack), but I believe that may cause a pop when switching

[armdnrdy]

I didn't want to seem negative but.......seems like a bad idea.

[Jussi]

I didn't want to seem negative but.......seems like a bad idea.

Negativity is okay . Could you explain why you think so?

[electrosonic]

Most likely when you turn the effect on it will make an audible pop as the capacitors charge up to their dc operating voltages.

A fuzz face draws something like 2mA whether it is on or off (ignore any indicator LED current). An alkaline battery is rated for over 500mA hours. A fuzz face in "standby" will take over 20 days to deplete the battery. I think you are solving a problem that doesn't exist and creating another.

My 2 cents.

Andrew.

[armdnrdy]

I didn't want to seem negative but.......seems like a bad idea.

Negativity is okay . Could you explain why you think so?

Try out your idea by connecting one of your effects into your guitar and amp. Now engage the effect, play the guitar and pull the power from the effect.

This is what will be happening when you engage and disengage the effect if you switch the power.

With the hundreds of guitar effects manufacturers that exist, I believe that if this were a good idea, it would be a standard.

Or you are the first to think of it and a genuine genius!! 

[Jussi]

Thanks for the replies. I'm just gonna add an on/off switch of its own to my fuzz face. I don't want to pull out the cable every time to save battery. I don't know how much 9v batteries costs elsewhere but here in Finland they are like 5 euros each.

[armdnrdy]

Build a power supply and outfit your pedals with DC jacks and you will never have to worry about battery drain or battery price again!

You will be freed!!!

[Mark Hammer]

ALL stompboxes leave the power connected to the circuit when in bypass mode.

It's not just popping (in fact it is almost never popping).  Rather, for effective stabilization of the power supply, there is usually a mid-to-large electrolytic cap (10uf-220uf)between V+ and ground.  When power is first applied, it can take a few moments for that cap to charge up before the circuit itself receives power.  So if power is removed when you bypass the effect, you will hear the bypassed signal immediately (after all, nothing to charge up, right?).  But when you switch the effect on, you will not hear anything right away.  I imagine that, for some styles of music, that brief delay will not be disruptive, but for many other styles it WILL be.

Since your concern is with being able to disable the battery without having to unplug cables, that suggests some other strategies.  One is to use switched pots where feasible.  You can buy pots in many of the standard values with a switch on the back.  Typically, the switch is tripped when turned fully counter-clockwise.  You can wire up your battery connector to the switch, and from there to the board.  This would let you leave all your pedals plugged in, but still be able to disable the internal battery when not in use.

On the more general topic of battery conservation, sometimes status indicator LEDs can draw as much current as the circuit itself!  Try to use high efficiency "superbright" LEDs where you can, and do so with high-contrast surrounds.  So, a yellow LED will need to be very bright, when set against a light-coloured background.  If installed in a dark-coloured chassis, or mounted in a black plastic bezel, there is good visual contrast, which lets it be visible at lower brightnesses.

Where it may have been common to use a 1k5 current limiting resistor with older low-efficiency LEDs, use of a superbright (let us say, minimum of 6000mcd rating) in the right conditions might permit a 15-18k current limiting resistor and still be just as visible, if not more.  That is a reduction of current draw by a factor of 10x!