batteries for 2 effects in one???

[gasmask]

Need help guys. I am building 2 pedals in one (Lovepedal COT50 with LPB-1) and
I don't really know how to connect batteries. To be honest, I do not even know if 2 batteries are necessary.


gas

[bluebunny]

Just join the 9V and GND connections on each board and then treat it as one.  A single battery will work fine.

[Mario44]

in situation b) voltage you will get is voltage from battery1+ voltage from battery2
in situation a) voltage is constant but they will last longer

so if you want to get 9V from 2 batteries use them in series

[Electric Warrior]

in situation b) voltage you will get is voltage from battery1+ voltage from battery2
in situation a) voltage is constant but they will last longer

so if you want to get 9V from 2 batteries use them in series

No. To get 9V from 2 batteries you need to connect them in parallel. Connecting them in series will bring the voltage up to 18V.

[Mark Hammer]

YOU call it two pedals.  The electrons couldn't care less.  It's one big(ger) 9v circuit that YOU have arbitrarily divided, provided separate switches for, and choose to think about as two different entities.

STOP DOING THAT!  

Where you are correct is in having a sneaking suspicion that the power requirements for the combined circuits will be greater in some manner than that of just one of those two components.  But that power requirement is in terms of current, rather than in terms of requiring an entirely separate supply.  Fortunately, the two subcircuits do not require that much current, individually, or in combination.  They will run for a while on a single 9v battery, and run perfectly well off one 9v adaptor.

HOWEVER...

When you consider that effects are never really "off", once you plug in, merely bypassed, the combined current draw of the two circuits, especially if you have indicator LEDs (which can sometimes draw more current than the effect itself), suggest hat you should consider using the highest efficiency LEDs you can, so as to extend battery life as long as possible.

LEDs are rated in millicandles.  The older red ones you'll find in Boss pedals from the 80's are likely to be in the 600milicandle (mcd) range or less.  These days, most suppliers can provide you with LEDs rated in the 6000+ range for pennies.  Because these are so bright, they don't require as much current to power them up to useful levels of illumination.  Remember, you're not trying tosearch through a dark closet with the LED; you just want to know if the effect is in or out.  So, where an older Boss or DOD pedal might stick a 1k-4k7 resistor in series with the LED to limit its current draw, use of a superbright will allow you to stick a 10-15k resistor in the same place to limit current draw even more, and still have ample brightness.

So, if yo want to stick both effects in the same chassis, with individual stompswitches and status LEDs, consider scoring some superbright LEDs, so that you'll be able to power the whole thing - both subcircuits and LEDs - frm a single paltry battery, for a long time.

[gasmask]

Thank you all guys for the comprehensive answers. 
I think I should set them in parallel, because this pedal will be
often used.

Thank you so much once again 
gas

[duck_arse]

be prepared for unwanted squealing. when two pedals become one, they sometimes interact via their common power supply. an R-C power-line filter might be needed.

[Mark Hammer]

Use ONE battery, not two.  If the two batteries wear down at different rates, they start interacting.  If you want to build in a switch to alternate between two batteries, fine, but two parallel 9v is just asking for trouble.

[Mario44]

lol, nevermind
thats why I always use dc adapter, never baterries

[aballen]

One battery, I don't know about the COT50, but the LPB1 draws very little current.

[gasmask]

Ill make it with one batt. Cot50 is simillar to lpb1 (just 2diodes, 1 cap and 2 resistors more than in lpb)