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2 effects in 1 box: How do I power them from the same 9V?
Posted: 05 Jan 2008, 19:59
by eman
I'm using two separate schematics (tyco oct and fuzz face) complete with 2 DPDT switches in one enclosure.
Newbie question: To power both, do I solder up each effect separately, then connect both to the same 9V power source?
Posted: 05 Jan 2008, 20:14
by briggs
You connect each effect's 9v and ground connections to each other then to the power jack/battery connector.
Posted: 05 Jan 2008, 23:20
by bajaman
You connect each effect's 9v and ground connections to each other then to the power jack/battery connector
I would prefer to isolate each stage by running a separate 100 ohm resistor to each effect from the + 9v supply socket or battery positive terminal and then drop a 220uf electrolytic(or larger if you prefer) from the circuit side of these resistors (2 electros required) to ground. By doing this you will decouple any signal voltage from travelling through the power supply rail between each effect and enhance operational stability by reducing or eliminating any intermodulation artifacts, particulary in the high frequency range. Make sure you connect the negative terminals of each electrolytic to ground.
cheers
bajaman
Posted: 10 Jan 2008, 18:20
by modman
--moved to the Workbench--
good topic though
Re: 2 effects in 1 box: How do I power them from the same 9V?
Posted: 04 Sep 2008, 10:21
by gshapzira
Hello, nOOb here...
bajaman wrote:You connect each effect's 9v and ground connections to each other then to the power jack/battery connector
I would prefer to isolate each stage by running a separate 100 ohm resistor to each effect from the + 9v supply socket or battery positive terminal and then drop a 220uf electrolytic(or larger if you prefer) from the circuit side of these resistors (2 electros required) to ground. By doing this you will decouple any signal voltage from travelling through the power supply rail between each effect and enhance operational stability by reducing or eliminating any intermodulation artifacts, particulary in the high frequency range. Make sure you connect the negative terminals of each electrolytic to ground.
cheers
bajaman
can you please explain this issue to me? if you could make a simple schematic of this it would be great!
Thanks a lot.
Re: 2 effects in 1 box: How do I power them from the same 9V?
Posted: 04 Sep 2008, 12:53
by bajaman
Hello - is this clearer
Add a 100 ohm resistor from EACH effect's +ve supply rail to the + 9v supply socket or battery positive terminal and then add a 220uf polarised aluminium electrolytic capacitor from EACH circuit's +ve supply rail to ground (connect the -ve pins of the capacitors to ground). This is a very old "trick" known as supply rail decoupling and it works surprisingly well, particularly when running effects from a common power supply adaptor. Many good designers already use this method of decoupling in their products - a schematic helps to identify this.
cheers
bajaman
Re: 2 effects in 1 box: How do I power them from the same 9V?
Posted: 21 Sep 2008, 17:05
by gshapzira
Thanks a lot Bajaman! Sorry for my silly question
English is not my native language and sometimes I just don't get the terminology.
Re: 2 effects in 1 box: How do I power them from the same 9V?
Posted: 25 Sep 2008, 05:11
by flood
bajaman's method is probably the simplest and best - BUT - if you want to really overkill it, you could use something called a DC-DC converter - that's what we were taught is used in ECG front ends to decouple the patient side )the converters i used were isolating types, up to 2.5kVDC)... but for this purpose, you'd be really overdoing it - DCDC converters are large, expensive, and need noise suppression components.
Re: 2 effects in 1 box: How do I power them from the same 9V?
Posted: 18 Oct 2008, 19:58
by rocklander
bajaman wrote:Hello - is this clearer
Add a 100 ohm resistor from EACH effect's +ve supply rail to the + 9v supply socket or battery positive terminal and then add a 220uf polarised aluminium electrolytic capacitor from EACH circuit's +ve supply rail to ground (connect the -ve pins of the capacitors to ground). This is a very old "trick" known as supply rail decoupling and it works surprisingly well, particularly when running effects from a common power supply adaptor. Many good designers already use this method of decoupling in their products - a schematic helps to identify this.
cheers
bajaman
so if I was looking at building a pedal that has 2X surpeaux in it, would you be saying that I should replace the 100uF cap there with a 220uF or adding another, and then put a 100ROhm between the two pedals supply rail (just before the last trim in this schem), or if it's on the same PCB would it be ok to leave the supply rail as constant?
Re: 2 effects in 1 box: How do I power them from the same 9V?
Posted: 18 Oct 2008, 20:12
by bajaman
Hi rocklander
You can probably leave the 100uf capacitor as it is on BOTH Supreauxs.
You will need to add TWO 100 ohm resistors (one in series FROM the supply +9v to the +ve 100uf electrolytic terminal of each Supreaux).
cheers
bajaman
Re: 2 effects in 1 box: How do I power them from the same 9V?
Posted: 18 Oct 2008, 20:21
by rocklander
sweet as then. again, thanks!
Re: 2 effects in 1 box: How do I power them from the same 9V?
Posted: 18 Oct 2008, 20:36
by rocklander
so would this layout be what you're suggesting? (I'm trying to make the boards long and thing rather than short and fat as ROG has them - suits my applications better)
top right is the decoupling R+cap
Re: 2 effects in 1 box: How do I power them from the same 9V?
Posted: 18 Oct 2008, 22:18
by bajaman
NO!!!!
the +9v battery lead connects to the 100 ohm resistor. The other terminal of this resistor connects to the +ve terminal of the 100uf electrolytic and the +ve rail for the circuit, where the +9v battery terminal was previously connected.
The same applies to all the other circuit/s. In this way ALL the circuits are separated from each other's +ve supply rail by 2 x 100 ohm resistors.
Hope this makes sense.
cheers
bajaman
Re: 2 effects in 1 box: How do I power them from the same 9V?
Posted: 18 Oct 2008, 22:44
by rocklander
clearly I'm not getting this then huh
so what you're saying is to put 100R between supply (9v battery and/or PSU) and (to all intents and purposes) the +ve rail for that particular effect.
then from that +ve rail (not the 9V supply) have an appropriate electrolytic to earth.
(apt. electrolytic is normally 220uF, but in the supreaux case it's 100uF)
is that it, or do I still have my dunce cap on?
Re: 2 effects in 1 box: How do I power them from the same 9V?
Posted: 18 Oct 2008, 23:18
by bajaman
yep - that is it!!
Re: 2 effects in 1 box: How do I power them from the same 9V?
Posted: 19 Oct 2008, 10:42
by rocklander
whew..
if that wasn't it I dunno how I was gonna get it
thanks again...
Re: 2 effects in 1 box: How do I power them from the same 9V?
Posted: 23 Oct 2008, 10:20
by bobo
I'm built 2 effects in one box. When I run by 9v battery no any problem. Once run by external power supply, it had sound like pop corn. I already put resistor 100ohm and capacitor 220uf per Bejaman advise. The problem is still unsolve. Anyone can suggest for this case.
Re: 2 effects in 1 box: How do I power them from the same 9V
Posted: 09 Apr 2011, 17:05
by timbo_93631
I drew this up in DIYLC. Does it look correct?
Re: 2 effects in 1 box: How do I power them from the same 9V
Posted: 29 May 2011, 03:34
by euronymous0001
that is correct
Re: 2 effects in 1 box: How do I power them from the same 9V
Posted: 14 May 2014, 09:14
by Masuto
Slightly different question here: any kind soul can suggest me a full offboard wiringlayout (since we are here.. including 9v single power supply) to have two pedals in one box? Ins, outs, cascading from guitar and outs including the final out to the amp?
Is my question silly enough/useless?
two effects in one box power distribution diagram.pdf