# changing from 1.5V battery to 9V battery

Discussion in 'Beginner Electronics' started by GuitarPsych, Mar 15, 2006.

1. ### GuitarPsychGuest

I have a very simple circuit that I run an electric guitar signal
through and I'm thinking of modifying it from a 1.5 V battery to a 9V
battery. What modifications do I need to do to the circuit? (I am
obviously a beginner).

2. ### JeffMGuest

...modifying it from a 1.5 V battery to a 9V battery.
Seems like a dumb idea. A cell is much cheaper than a battery.
What advantage could there possibly be?

3. ### GuitarPsychGuest

These are reasons just off the top of my head:

1) To go through the process just to learn.

2) To standardize all my effects pedals so I only have to carry 1 type
of extra battery, therefore minimizing carrying space and weight and
minimizing the chance I will be out of the one I need.

3) The standardization will also eventually allow me to work on a
project that allows all my pedals to run on a power supply that accepts
multiple pedals. The power supply works with pedals expecting 9V. I am
unclear if it would work with pedals expecting 1.5 V... I have my
doubts, therefore the conversion project.

4) The 1 AA battery dies quickly.

4. ### GuitarPsychGuest

I'd rather not make this about a debate as to whether it's a good idea
overall. I may in fact not actually do the conversion. Regardless, I
would just like to know how to go about doing it, IF I chose to.

5. ### defaultGuest

If you plan to run your stuff on a power supply the 1.5 volt can be
met with one of the three terminal regulators to step down the voltage
from 9. I think the LM317 outputs something like 1.2 volts with no
adjustment resistors. Goggle for it and the data sheet will tell you
how to connect it and how to calculate the resistor to give the output
voltage you want.

Running it with a 9 volt battery will just waste a lot of power and
end up costing a lot more.

You could make a buck switching supply to lower the voltage
efficiently - but you're still talking about a more expensive battery
cost.

Going the other way, 1.5 to 9, makes more sense if size isn't a big
concern. Particularly if you can use D batteries.

There's a semi-obsolete IC designed to do just that - Part is the
TL496. Designed to take 1.5 or 3 volts and output 9 volts at 20-40
milliamps.

Someone was marketing a kit for the TL496 with all the parts and
circuit board to make a 9 volt battery eliminator.

6. ### GuitarPsychGuest

I can't tell if you are being sarcastic, but if not, all I can do is
again ask my original question. It is a very simple circuit, 9
resistors and 4 capacitors. I'm just wondering in general what
modifications I would need to do if, on the diagram it lists a 1.5V
battery and I want to use a 9V battery. Would I raise/lower the values
of certain resistors/capacitors? Would I need to do anything?

7. ### GuitarPsychGuest

I must be asking this question in a way that is throwing people off,
because there seems to be a lot of resistance to actually answer the
question. Let me try another way:

Let's say a friend of yours is in an electronics class and given a
simple circuit design, 9 resistors and 4 capacitors, with a 1.5V battery
power supply. The assignment is to test the circuit to see if it would
function if the battery power supply were changed to 9V. How would you
suggest to your friend to do that? What would they look at in the
circuit? And if something would need to be changed, what would it be?
resistors/capacitors? etc.

9. ### Tater SchuldGuest

rather than question why you would want to do so, I'll suggest an answer.

I assume you either want to have all your gear run off one power supply, or
you want to keep buying only one type battery(I suggest the single supply

I don't think a LM78015 (does this exists?) would do it as the input voltage
would be too high and cause a lot of juice to be lost due to heat (and
lessen the life of your battery a LOT)

tell us what the power usage in milliamps is and maybe you could just use a
simple resistor voltage splitter.

I can almost bet that someone is going to suggest a DC-DC converter that is
a 1000 times more complicated that what you need.

in fact. here's the circuit you need......2 resistors tied in series. one
resistor will be 6 times the size of the smaller resistor. the smaller
resistor needs to equal the total resistance of the circuit in question,
which you calculate using ohms law and the current capabilities of the
circuit that needs the 1.5 volts.

corrections anyone?

10. ### GuitarPsychGuest

Ok, thanks for the info. Regarding linear.com, I can't seem to figure
out what software to download ... there are many options yet none
clearly say "circuit simulator".

11. ### JeffMGuest

You're looking for a SPICE package:
Linear Technology's Simulation Program with Integrated Circuit Emphasis
..
..
The gold standard is
to leave the name of the person to whom you are responding
and just enough of the previous post to give "context"
what the last part of the thread mentioned.

Your new text goes BELOW that.
(Note how I did it.)

12. ### nikhileleGuest

better u use a step-down/buck DC-DC convetor which will give u a nice
1.5v from a 9V battery.

U might be doing this to have longer life of battery.

if u r using 9V - 1.5V linear voltage regulator you will waste a large
amout of power.

So go for switching regulator.
they price less then 1\$.

13. ### Tater SchuldGuest

got a source for these?