2-in1 Pedal Wiring with -9V Charge Pump

[brucer]

Hi Madbeaners,

I'm building a 2-in-1 Madbean Mangler/Rangemaster with a General Guitar Gadgets charge pump changing +9V DC to -9V DC.  I've searched for wiring schematics and distilled what I've seen to the attached sketch.



I'd really appreciate it if some of you wiser and experienced folks could let me know if I've got it right before I wire it up and connect the power.  Sorry it's a bit rough.  It seemed easier to draw freehand that CAD'ing ...

Thanks, Bruce.

[m-Kresol]

Looks fine to me. Just to make sure, let someone else reconfirm that.

[jkokura]

The battery snap is incorrect, as is the input jack.

Instead of running the black wire from the battery snap to a common ground connect, it should connect to the ring lug of the input jack, and only that wire should connect there. That means that when a 1/4" plug is inserted into the jack, the connection between the black snap wire and ground will be made, and when the plug is removed the connection will be broken and the battery will not be drained.

Jacob

[electrosonic]

Is it standard practice to route the ground from the charge pump through the input jack? It seems to me that would be prone to adding noise from the charge pump.  Would it make more sense to make the ground connection switch the charge pump on via a transistor? 

I know it is standard practice to use the input jack to switch the pedal on, but that only makes sense if you are using batteries.

My preferred scheme is to short the input to ground when no jack is inserted and switch on/off with the output jack, or forgo the switching completely.  Simply unplug your pedal board when not in use.

Andrew.

[jkokura]

Is it standard practice to route the ground from the charge pump through the input jack? It seems to me that would be prone to adding noise from the charge pump.  Would it make more sense to make the ground connection switch the charge pump on via a transistor?

In this case, all the grounds will end up in the same place anyway. I would say that it's better practice to incorporate star ground than to worry about noise being added from the charge pump.

I know it is standard practice to use the input jack to switch the pedal on, but that only makes sense if you are using batteries.

There is a Battery clip in the image above...

My preferred scheme is to short the input to ground when no jack is inserted and switch on/off with the output jack, or forgo the switching completely.  Simply unplug your pedal board when not in use.

I agree that it's best practice to unplug all pedals if you're using batteries. However, on my pedalboard, it would completely destroy the arrangement to unplug and plug in every pedal every time I did or didn't use it. I actually think the best route is to use the switching DC jacks, and then use a dummy 9V plug to switch the battery on/off if you need to switch it out. Essentially, if you use the common switching DC jacks, and the input jack 'trick,' both unplugging the input AND plugging into the DC Jack do the same thing - remove the battery from the signal path.

I think it's just tradition to use the input jack to switch the battery in/out. You're correct that grounding the input can be very useful, as can using the output jack to switch the battery in/out. In either case though, you can't connect the battery snap's - connection to the common ground, it has to be isolated via either jack's ring lug in order for it to break connection.

Jacob

[brucer]

Thanks for the comments and corrections.  Much appreciated.

If I wire the black wire from the battery snap to the ring lug of the input jack, then do I now use the DC jack as the common attachment point for the star ground (instead of the sleeve of the input jack as shown in my first post)?

Also, the GGG wiring diagram for the charge pump (Road Rage was out of stock) shows an "SW" pad connected to the sleeve of the input jack:



... though their Fuzz Face with Charge Pump wiring diagram shows the same pad connected to the ring:



Does the "SW" pad go to the sleeve as suggested ... or does it somehow negate the need to wire the black wire from the battery snap to the ring lug?

Sorry if the answers obvious, but I'm not seeing it.

[jkokura]

The difference with that one is that it's labeled '9V power source' not 'battery.' I think the intention there is to show that it's the wiring for a 9V source, but not necessarily for a 9V battery and DC Jack in one.

The second diagram is the one you should be looking closer to.

Jacob

[brucer]

Thanks Jacob!

[m-Kresol]

Thanks for the comments and corrections.  Much appreciated.

If I wire the black wire from the battery snap to the ring lug of the input jack, then do I now use the DC jack as the common attachment point for the star ground (instead of the sleeve of the input jack as shown in my first post)?

Also, the GGG wiring diagram for the charge pump (Road Rage was out of stock) shows an "SW" pad connected to the sleeve of the input jack:



... though their Fuzz Face with Charge Pump wiring diagram shows the same pad connected to the ring:



Does the "SW" pad go to the sleeve as suggested ... or does it somehow negate the need to wire the black wire from the battery snap to the ring lug?

Sorry if the answers obvious, but I'm not seeing it.

I guess the "switch" pad on charge pump just connects the ring of the input to ground and is designed so the battery is then grounded. So it should be the same as if you connected the battery clip directly to the ring of the input. I assume it's to make things tidier. In the first pic the labeling is not the best, but the switch pad is actually connected to the ring (the shorter pin).
But all in all, Jacob's right of course. Use the second pic version and you should be good to go. Good luck, I'm looking forward to your build report

[brucer]

Thanks Felix.  I see now that I interpreted the first GGG picture incorrectly and that both diagrams route the "SW" pad of the charge pump to the ring of the input jack.  Thanks for pointing that out.

It seems that I can go with the diagram at the start of the thread and that battery power will be switched at the input jack.  I'm hoping the grounding scheme is sufficient to keep circuit noise down, but I can tell from your and Jacob's notes on grounding/switching that I have a lot to learn in that area!