Are these readings correct?

[formerMember1]

i measured the power consumption of my RM clone.
With LED w/ 1 k resistor
Off: 16.7 uA
ON : 6.74mA  

NO LED:
OFF:16.7uA
ON:16.8uA

Could this be correct?  Does an LED really take up that much power?  I wil HAVE to higher the resistor.

How much hours of use should i get around with no LED w/ the above readings?

thanks :wink:

thanks

[R.G.]

The numbers look reasonable at least.

An LED with 9V across the LED and a 1K resistor leaves about 7V for the resistor, so 7V/1K = 7ma, close to your number.

9V batteries run about 166 to 400 ma-hours when discharged at 1/10 of their nominal capacity rating (that is, about 16 to 40 ma). The actual battery capacity changes when used at other ratings.

But your battery would last a long time without the LED - or just using a super-bright LED and only very little current.  You might get a $4.00 ultrabright blue or white LED and run it down in the sub-1ma range for longer life. That would pay for itself in batteries in short order.

Craig Anderton came up with another way to get longer battery life. National Semiconductor made a chip that stores current in a capacitor and flashes an LED about 1/second. That makes for a low average use and a much longer battery life, too.

[formerMember1]

thanks R.G. :wink:

[formerMember1]

I read somewhere on this forum R.G posted to find out how many hours a pedal will last with a certain battery you do the following:

divide the pedal's power consumption by the battery capacity to get hours.

Say my pedal takes 16.7uA when on without LED, then the LED uses 200uA so i now have my total pedal' power drain at aproximately 216.7uA, right?  So if i divide that by a carbon zinc battery with say approximately 228mAh then i should get the total hours?  But i always end up with a really small decimal number. :roll:

I have read things online about mA and uA but confused about it.  I know uA are smaller than mA, but how much uA = 1mA    ?  

I think my problem is i am dividing apples and oranges.  Like one figure is in uA and the other figure is in mA?

oh boy... :roll:

[formerMember1]

anybody can give me some help about my last post :wink:

[R.G.]

1ma = 1000uA

228maH/216.7uA = 1052Hr.

228maH = 228000uA-Hr.

Most carbon zinc are more like 160ma-hr.

[formerMember1]

thanks man, you have been very kind and helpful.  I finally understand some things that i have been confused on for quite sometime and had trouble learning.  I know understand!