How do I connect a voltage regulator in this setup?

Thread Starter

Acegikmo

Joined Jan 27, 2012
5
Hello!

I'm working on making a battery solution for a device which doesn't support it by default. I'm replacing the original outlet+adapter configuration with a single battery with a cable.

I'm pretty sure I've got the right battery and the right voltage regulator.

However, I'm not entirely sure how to solder this together!
What I wonder is; Will this work? (See image)





Which means, solder it together in the areas marked green, and the same with the little plug on the right.

Thanks in advance :)
 

kubeek

Joined Sep 20, 2005
5,621
What is the type and voltage of your battery and what is the desired output voltage?
Also the regulator type? If you´re using the typical 78xx series, remember that you need at least 2.5V higher voltage on the input. Also, what is the current requierd by the load?
 

PaulEE

Joined Dec 23, 2011
423
Hello!

I'm working on making a battery solution for a device which doesn't support it by default. I'm replacing the original outlet+adapter configuration with a single battery with a cable.

I'm pretty sure I've got the right battery and the right voltage regulator.

However, I'm not entirely sure how to solder this together!
What I wonder is; Will this work? (See image)


Which means, solder it together in the areas marked green, and the same with the little plug on the right.

Thanks in advance :)
If your regulator is indeed a standard 78xx regulator and you do have the proper difference between the in/out terminals, and if you do not exceed the regulator's current draw, this setup looks fine.

Remember to check polarity on that output jack!
 

hgmjr

Joined Jan 28, 2005
9,029
Keep in mind that the 78XX series of three terminal voltage regulators have a built-in thermal protection circuit. If you overload the device with too much current, the regulator will shut itself off until the overload is removed and the device cools down below it thermal temp limit. This typically saves the device from self destructing in an overload condition.

hgmjr
 

Thread Starter

Acegikmo

Joined Jan 27, 2012
5
The battery is a Lead-Acid battery at 12V.
The voltage regulator is L7809CV 1.5 A.
The adapter I'm trying to replace says 9V 1.7 A.
The adapter has this symbol: http://upload.wikimedia.org/wikipedia/commons/8/84/Centre-positive.svg

So I should connect the brown wire to the inner metal parts of the plug, and the blue wire to the outer metal part, right?
According to the person at the store, the voltage regulator should be fine, even though the adapter says 1.7 rather than 1.5.

I really have no idea myself, so if any of this is completely wrong, let me know!
 

PaulEE

Joined Dec 23, 2011
423
The battery is a Lead-Acid battery at 12V.
The voltage regulator is L7809CV 1.5 A.
The adapter I'm trying to replace says 9V 1.7 A.
The adapter has this symbol: http://upload.wikimedia.org/wikipedia/commons/8/84/Centre-positive.svg

So I should connect the brown wire to the inner metal parts of the plug, and the blue wire to the outer metal part, right?
According to the person at the store, the voltage regulator should be fine, even though the adapter says 1.7 rather than 1.5.

I really have no idea myself, so if any of this is completely wrong, let me know!
Hook up the output of the regulator to the middle of the output jack.

The adapter claims it can source 1.7 amps; whether or not your device ever sinks 1.7 amps is something that is up to you to decide...

You also might entertain the idea of an inline fuse to avoid *POP* *FIZZ* (letting the smoke out of the regulator, wires, battery, or load device, or all those things!)

Otherwise, you should be fine.

What are you connecting this to?
 

Thread Starter

Acegikmo

Joined Jan 27, 2012
5
I'm connecting it to a Kaossilator Pro, a synthesizer!

What kind of inline fuse would I need in this case? Is it a 1.7 A fuse or something I need?
I've never done anything with electronics before, so I'm not sure which parts to get and how to connect them
 

PaulEE

Joined Dec 23, 2011
423
I'm connecting it to a Kaossilator Pro, a synthesizer!

What kind of inline fuse would I need in this case? Is it a 1.7 A fuse or something I need?
I've never done anything with electronics before, so I'm not sure which parts to get and how to connect them
If you go to radioshack and ask for a "1.5 amp" slow blow fuse and inline fuse holder, they should be able to hook you up with those things.

The fuse would simply go inline with the input of the regulator. It's just a safety measure for the equipment, that's all.
 

Thread Starter

Acegikmo

Joined Jan 27, 2012
5
Shouldn't it be in line with the output of the regulator? Since that's the current/voltage that matters for the device, isn't it?

I'm still a bit confused as to what fuse to get. I thought it should be a 1.7 A fuse, not 1.5. Or does it not matter that much? :)
 

Pencil

Joined Dec 8, 2009
271
Shouldn't it be in line with the output of the regulator? Since that's the current/voltage that matters for the device, isn't it?
Before the regulator will provide a measure of protection in case of
short circuit at the regulator. The current is coming from the battery.
The amount of current "before the regulator" and "after the regulator"
is basically the same value.

I'm still a bit confused as to what fuse to get. I thought it should be a 1.7 A fuse, not 1.5. Or does it not matter that much? :)
You probably will have trouble finding a 1.7A fuse. A 1.5A fuse will
be more readily available, and probably sufficient, Yor adapter can
provide a maximum of 1.7A, your requirements are most likely less.
Check your device being powered, it may have a fuse for its own
protection.

You should also find a datasheet for the regulator you are using and look
to see what capacitors are recommended from the input/output to
ground, Usually a .22uF or .33uF is recommended on the input side
and a .1uF on the output side. I believe this is a link to your DATASHEET,
look at page 28, Figure 8. You may not need the capacitors recommended
since you are powering from a battery but, it is always good practice to follow
manufacturer recommendations.

Another point to consider is if the current requirements of your powered
device is more than a few milliamps, you will probably will need a heatsink
on the regulator to avoid the possibility of overheating the regulator. If the
regulator oveheats, it may shut down to protect it self, or be destroyed.
 
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Thread Starter

Acegikmo

Joined Jan 27, 2012
5
Are those necessary?
I hooked everything up, and it works perfectly fine!
Haven't tried for more than a minute though, but still :)

Thanks everyone for the help!

Edit:

The voltage regulator does get quite hot after a minute. Should I be worried?
 
Last edited:

Pencil

Joined Dec 8, 2009
271
Are those necessary?
Highly recommended. Without them the regulator could
oscillate wildly and destroy itself. You wouldn't even know
it was happening until it died.

The voltage regulator does get quite hot after a minute. Should I be worried?
Add a heatsink, even if the regulator does not get hot enough
to go into thermal shutdown, the lifespan/reliability will be greatly
improved. In a pinch, anything that conducts heat attached
securely to the tab of the regulator will help, although bona fide
heatsinks are readily available.
 
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