Topic: JB3 external power question

[eclark]

why would a 9.6v 1600mAh battery work with my jb3/vr but a 7.2V 3300mAh batterny WONT? when the 7.2v is connected it powers up but then shuts off as soon as the HD tries to spin up. the 9.6 volt works great AND powers my ua5 at the same time...

i swear i have the worst trouble with electronics   
also the voltage regulator that i use is the 7805

thanks

[caymanreview]

is it made for spcifically 9v input? did you make it?

[eclark]

nah it doesnt need 9V, radioshack website says it can go up to 35V. i did make it myself. i posted pics on this thread right here:
http://taperssection.com/index.php?topic=76391.0

ALSO, it doesnt work on the 9V battery you sold me dustin (typical 5400mah 9v walmart battery)
isnt that the wierdest thing

KLowe made me a VR with the same stuff and that one doesnt work either....
i must have some bad karma or something

[caymanreview]

is the polarity right in all your cables/connections?

[caymanreview]

i thought id read somewhere that some of the actual parts in a vr type box require a certain amount of voltage to output whatever voltage you are looking for, ie you are looking for 5v i believe, and maybe that part in the vr box that outputs 5v needs more than 7 volts to work???

i may be just talking out my ass, i read so much stuff on here and it gets all jumbled in my head

[eclark]

is the polarity right in all your cables/connections?

yeah the polarity is all correct and everything, ive tested everything will a voltameter several times. i really dont know what the deal is, its just one of those wierd things i guess...


i used the 1600mah battery last night and i got about 3 hours out of it on the jb3, so im just gonna take the 3300mah 7.2v one back.
thanks for your help though

emery

[caymanreview]

are you using any of the 2 internals with the external source?

[eclark]

are you using any of the 2 internals with the external source?

nah, i dont have ANY internal batteries (HINT HINT) if anyone wants to sell me some...
i just took the 7.2 back and got another 9.6V 1600mAh battery at radioshack for 9 dollars so im good. ill probably wire them up together so ill have a 9.6V 3200mAh battery for the JB3 and UA5 if i want to run that too. all rechargeable. i hit radioshack up for that christmas sale 

anyone know if i wire them together will the charger still work the same, just take longer??
thanks

[caymanreview]

you need some internals, at least one. i ran the jb3 for a looong time back in the day, never needed more than the 2 internals. look on ebay, im not sure if they still float around there or not.

post an iso in the yard sale, someone's bound to have an internal or two you can buy!

[SparkE!]

why would a 9.6v 1600mAh battery work with my jb3/vr but a 7.2V 3300mAh batterny WONT? when the 7.2v is connected it powers up but then shuts off as soon as the HD tries to spin up. the 9.6 volt works great AND powers my ua5 at the same time...

i swear i have the worst trouble with electronics   
also the voltage regulator that i use is the 7805

thanks

The main problem is your 7805 regulator.  It requires at least 7.2 V to make 5 V out when there is no current drawn.  As soon as you start to draw current, you need even more voltage, but your battery voltage actually sags. It might work for a little while when you have a completely full battery, but it won't last long.  If you are going to use a 7.2 V battery, you're going to need a voltage regulator that has a lower dropout voltage and that probably means your best bet is to use a switching regulator design of some sort.  Also, don't be surprised if you have problems in the summer if you use a 9.6 V battery with your 7805.  Those things let their output voltage sag when they get too hot.  You might find that you have to keep your regulator in an ice box to keep it running at a summer festival.  The 7805 is easy to use from a circuit design standpoint, but they are not the best solution for most applications.

[pigiron]

ditto what SparkEl said about input voltage...

Check out the National Semiconductor datasheet at http://www.national.com/pf/LM/LM340.html... the V_IN shown on page 4 of the PDF file says that the minimum input voltage required to maintain regulation is 7.5 Volts.

Also, here's what an old post (which now seems to be purged) said about the ratshack 7805 on the JB3 (but they probably change chip vendors all the time):

http://www.oade.com/cgi-bin/miva?Forum/technology/showmsg.mv+message=14780     
                                                                               
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Re: Battery life of Jukebox 3 (anyone build a batt                             
Subject: Re: Battery life of Jukebox 3 (anyone build a batt Date: Mon, 28 Jul 20
03 12:50:03 - (EDT) From: datgeek                                               
OK I have done LOTS of testing on external power sources for the JB3 1:) do NOT
run the INTERNAL batteries if youare using an external DC Source.. 2:) RE 5v Reg
ulator make sure it is a 1.5+A regulator, the 1amp ones I tried from Rat Shack w
ill NOT do. and get a BIG Heat sink.. 3:) WHat I use and works for me >> I got a
 1.2amp 4.5v DC Adapter (I can't find the accuall Creative Labs DC Adapter in st
ock ANYWHERE) but I picked up a Rat SHack 1.2A multivoltage Car adapter, on the
4.5v setting it works GREAT (Remember take OUT the Internal battery first) I run
 a 8AMP 12V SLA into my JB3 & My UA-5 I have gotten 10+ hours out of this with N
O problems theoretically the system draws about 600-800ma durring recording, the
 Boot up process is where you suck the juice using the JB3, it might pull a full
 1amp+ during startup... for regulay 4 hour shows a regular 4ah 12sla should do
just fine. hope this helps Dail Reed www.datgeek.net dail AT datgeek DOT net

Don't know if this will help, but here's some very crude current measurements I took back in the day:

• Removed internal batteries from NJB3.
• Attached digital ammeter (accuracy +/- 20mA) to the NJB3 (microcode level 1.20.06) DC input, powered by a Jensen JCD22A Auto DC Adapter (1A max) at the 5V setting, hooked to a 12V 12Ah SLA battery.
• Performed a "Line-in Recording" WAV 44.1KHz with no microphone attached.
• When the hard drive was running, measured 870mA; during idle 330mA; but the measurements varied by 10's of milliamps.
• Total guess that the hard drive is drawing current very roughly 1/3 of the cycle (maybe less).
• If the guess is true, then rough average current draw while recording is                                                                      (870 + 330 + 330) / 3 = 510mA
• Measuring current spikes is difficult with a digital ammeter, but saw short peaks in the upper 9XXmA range while recording.
• When not recording and sitting idle, the current draw was a steady 100mA. During same state with the backlight on, the draw was 140mA.
• Interestingly, the unit drew a steady 47mA with the JB3 powered off.

Here's wishing good luck on your project.

[rowjimmy]

You are working too hard on this, imo. a simple 5v L-Ion with the right tip will make your day.

http://taperssection.com/index.php/topic,29230.msg952161.html#msg952161

This battery seriously runs the jb3 forever. All day @ a Fest, to be sure.