OK. Let me try to explain this...
I have a trusty Maxell P-13 FM transmitter.
Not the greatest thing in the world - but it's
teeny and is a very good point to point transmitter
for in the house.
I used to have another one but I destroyed it.
Here's what happened. The P-13 uses 3 AAA
batteries. They last a while and then they run
down. I thought I could attach some wires to
the battery terminals. Then I could run those
wires out to a power source that would last longer.
Such as - 3 D batteries in their holders. The voltage
would be the same. It would run a lot longer. Heck -
there isn't even a power supply involved here. It's
just some bigger batteries. I sounds like a good idea,
right? The transmitter would just take the current it
needed and go for a longer time.
Like I said before... Right?
Well, no. It didn't work out that way.
I hooked up the batteries and this particular
P-13 never worked again. (The polarity was
correct. I'm assuming there was no reverse
polarity protection on this kind of item.)
It was as dead as a door nail. (Whatever that
means.)
One trusty P-13 into the wastebasket.
My friends said that shouldn't happen. I
agreed. And then I thought - the device's
teeny chip (surface mount, whatever) countn't
handle the high inrush currect. It just wasn'ty
designed to do that.
But I didn't quite believe the above. And I
actually blew up a few other small devices,
some good MP3 players and such.
I have to go.
What do you guys thinK.
Brooce, WLP
Brooce WLP I'm glad you posted that information, because I want to build a power supply for the Scosche FMT4R, and I sure don't want to fry the rare device.
Also I want to replace the battery in my home-made mic with a power supply.
Please find out what we're doing so we'll know.
There's no inrush of current....doesn't work that way. The current depends on the resistance and the supply voltage only.
Your thing took 4.5 volts(3AAA batteries). You can use batteries the size of garbage cans....as long as the voltage is 4.5 volts the SAME AMOUNT OF CURRENT will exist....the milliamps used won't change. You just have a lot more reserve power. So you must have done something else you're not aware of.
I use an MP3 player for my station music source and I can't have down time recharging every 10 hours so I open it up, remove the stupid LI-ion battery in there, rated voltage 3.8volts and work it with 3 batteries at 1.5 volts. I connect wires to the internal battery points, bring the wires outside the case and get a 3 C battery holder with snaps and mount it with double sided mounting tape and with 3 C batteries I have close to a month continuous run time. Works great!
So something is wrong when you are doing this.
Mark
Hey Mark good job on opening that
MP3 player. I've tried to do
that and things didn't go so well.
Yup, you are probably right.
I say "probably" because I agree with
what you say.
The thing is: my brain is telling me that
I didn't make any mistakes.
But I make lots of mistakes every day.
So... you must be correct.
I can tell by what you are saying that you
know what you are doing.
And I'm not as young as I used to be.
Best Wishes,
Brooce, WLP
Did you solder the wires to the correct battery contact springs?
As for Mp3 player mods it's hard, you're dealing with very small things....one slip and you can screw it up. Need a good desk magnifier. Have to be careful opening it up also.
Mark
there is something else going on. I have seen small battery operated devices where the batteries are installed in series but hidden away is a tap made between two cells so there are multiple voltages available for the circuit. For example, a three cell pack could have taps to give the circuit 1.5, 3, and 4.5 volts.
Simply stacking the batteries and connecting the ends to the circuit could miss supplying another voltage from the overlooked tap.
Not saying this is how it is wired in your case but just something to consider.
Neil
A few years ago ,I bought a set of Radio Shack frs/gmrs walkie talkies that came with a drop in charger, both radio's have a NI-MH 4.8 v 700mAh battery pack. After about 6 months the batteries in both radio's refused to hold a charge and I never tried to figure out why.
I put them away in a closet and forgot about them. Just the other day I ran across those walkie talkies and thought since the battery packs were dead, maybe i should read the manual to confirm whether they can be used with normal alkaline AAA batteries or some other form of power source.
Turns out they can run just fine on 4 AAA batteries, I just need to order new battery packs which seem to be kind of a universal battery for other devices as well. There is a port on the side of these things that allow the operator to connect the radio's to a 12 v to 9 volt converter in the car/truck.
I like these radio's, the antenna looks like it was meant to travel longer distances, the antenna is a rubber duck sort of and is about 6-7 " long. They do well on low power all day long, but on high power they drain the batteries fast. I am not licensed for GMRS so I don't use high power.
Sometimes this is considered in the design of the device. A larger capacity battery can maintain a higher current level easier than a smaller one. The device draws a determined amount of current (Per Circuit Resistance) which drops the voltage of the battery to a designed level. A larger current capacity battery can supply a higher current, which will hold the voltage to a higher level than what the unit was designed for..
Just a possibility..
I seen one of these recently at a surplus store, it looks a bit like a yoyo correct?
I plan on buying one of those the next time I'm there. I'll let you know what I find out as I never power battery operated toys off their batteries and have never had issues with blown components.
Remember Mr. Microphone from Ronco? It used two AA cells, 3 volts, i powered those up using a 9 volt wall wart at 500 mA and it worked fine.
Bruce.
I just wanted to let you guys know
I just read what you had to say.
I'll be back with a few more comments.
Very best wishes,
Brooce
WLP-FM 90.9 MHz Part 15.239
(Just for fun the last couple of days,
anyway.) (The guy across the street listened
to my "station" on his car radio when he was
washing his car. After we move there will be
more WLP in some form.)