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Author Topic: SOLVED: battery hack help  (Read 2903 times)

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Offline mblindsey

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SOLVED: battery hack help
« on: December 29, 2007, 10:20:35 PM »
My daughter destroyed her portable DVD player.  The battery from the device is detachable, and I figure I can use it power something in my recording bag.  It is a rechargable 7.2V NiMH battery.  I opened it up and took a picture.  I'd like to power my MT II with it.  Any pointers on how to get it work as a 5V USB battery?  I'm just looking for that spare...a fun project, if you will.  Or, is it even worth the hassle?  I know other rechargables for the MT II can be had for not much.

Thanks,
Michael
« Last Edit: December 31, 2007, 10:46:37 PM by mblindsey »
Mics:  Microtech Gefell m200/M20/nBob Actives>PFA, CA-11
Pre's: USB Pre2, 1x V3, 2x V3 w/optimod, MP2, Church Ugly
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Offline SmokinJoe

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Re: battery hack help
« Reply #1 on: December 30, 2007, 12:27:56 AM »
Yes, go to Radio shack, etc, and get a 7805 voltage regulator "chip".  It has 3 pins.  Across 2 pins will go your 7.2v and across 2 pins will come out 5V and they will share a common ground.  Ideally you put capacitors on each side as a "shock absorber" when you plug it in (no pun intended), but some people don't.  Voltage regulators get hot, and you should attach it to something metal to keep it cool, like an Altoids box, but make sure the electrical leads don't short out.

Find a spare USB cable with the appropriate end on it, cut it, and you will probably find red,black,green, and white wires.  Red is +5V, Black is Ground, and these go to your voltage regulator, ignore green and white.

The most important thing is to check and double check everything with a voltmeter to make sure you don't have something backwards BEFORE you plug it into your MT.  If you have something backwards, bad things might happen to your MT, so make sure everything is correct.

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Offline mblindsey

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Re: battery hack help
« Reply #2 on: December 30, 2007, 09:51:42 PM »
Thanks...It worked!  I picked the 7805 voltage regulator (276-1770) from Radio Shack and soldered it up using a spare USB extension cable I had.  While I was at Radio Shack, I also picked up some capacitors.  Specifically, I purchased Radio Shack part numbers "272-1436" (10uF Tantalum Capacitor) and "272-1026" (22uF Electrolytic Capacitor).  I attempted to solder my pieces per these instructions I found on the web for a similar device:

http://www.popsci.com/popsci/how20/82583742e7cb0110vgnvcm1000004eecbccdrcrd.html

Unfortunately, I was still getting 7.2V when I had it wired up like that.  I must have done something incorrectly.  So, I just ended up building it without the capacitors.  So, two more questions:

1.  Does anyone have a pic of what this set up would look like with the capacitors + regulator?

2.  The case I have this thing in is plastic.  There is no metal to attach the regulator to.  Is heat dissipation something I should fret over in this build (going from 7.2V -> 5V)?  If so, is there another solution other the altoids box I can take advantage of?

Thanks in advance,
Michael 
Mics:  Microtech Gefell m200/M20/nBob Actives>PFA, CA-11
Pre's: USB Pre2, 1x V3, 2x V3 w/optimod, MP2, Church Ugly
Decks: SD MixPre 6 II, R44 Oade Concert Mod, M10
Playback: Grace m9xx->Sen HD 650, Fostex TH-X00, HIFIMAN HEXX
Mixing: RME Fireface UFX->Reaper/Izotope->Yamaha HS8

Offline mblindsey

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SOLVED: battery hack help
« Reply #3 on: December 31, 2007, 10:43:26 PM »
After a couple of more trips to Radio Shack, I was able to follow the instructions in the link from my previous post to add the capacitors before and after the voltage regulator.  I actually purchased a "breadboard" (# 276-002) to test everything out prior to soldering, and some Helping Hands (# 64-2991).  These things are a must for newbies like me.  Ultimately, I soldered everything to a "Dual General-Purpose IC PC Board" (#276-159) that I cut down a bit to fit inside the battery case. 

Never had a lesson.

Next up...a flux capacitor.  Or maybe, I'll try to build something similar in an altoids box to so that I can run my MT II off of one of the 3 wally world batteries that I have.

Thanks again for the pointers.

--Michael

p.s.  My apologies for the blurry pics.  My digi camera leaves much to be desired.
« Last Edit: December 31, 2007, 10:45:47 PM by mblindsey »
Mics:  Microtech Gefell m200/M20/nBob Actives>PFA, CA-11
Pre's: USB Pre2, 1x V3, 2x V3 w/optimod, MP2, Church Ugly
Decks: SD MixPre 6 II, R44 Oade Concert Mod, M10
Playback: Grace m9xx->Sen HD 650, Fostex TH-X00, HIFIMAN HEXX
Mixing: RME Fireface UFX->Reaper/Izotope->Yamaha HS8

Offline mblindsey

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Re: SOLVED: battery hack help
« Reply #4 on: January 06, 2008, 11:21:05 AM »
I fully charged my MT II and this battery.  Here is what I found:

1.  When I plugged the battery into the MT II, it started charging.  Moments before, I had just uplugged MT II from the wall and it showed that it was fully charged.  The "charging" lasted at least 25-30 mins. I'm not sure why this happened, and it bugs me.

2.  My homemade external battery lasted a little over 4 hours, or enough to fill up a 4 GB card recording at 24/48, with a slightly more to go.

3.  The device seems to have switched seemlessly over to the internal battery when the external ran out of juice.  Although I don't know exactly when it occurred, I ended up with the 3 files I expected:

1.9 GB (1999953028 bytes) or 01h 55m 44s in Audacity
1.9 GB (1999854724 bytes) or 01h 55m 43s in Audacity
83.8 MB (87841924 bytes)  or 00h 05m 04s in Audacity

I didn't take the time to examine the first file, which is where the battery switch would have occured, to see if there were any anomalies.

4.  With this external battery and the internal battery, I can record for a little over 8 hours.  The MT II battery level indicator was on the "last bar" when I stopped recording (twice filling up 4 GB card at 24/48).

--Michael




« Last Edit: January 06, 2008, 09:15:05 PM by mblindsey »
Mics:  Microtech Gefell m200/M20/nBob Actives>PFA, CA-11
Pre's: USB Pre2, 1x V3, 2x V3 w/optimod, MP2, Church Ugly
Decks: SD MixPre 6 II, R44 Oade Concert Mod, M10
Playback: Grace m9xx->Sen HD 650, Fostex TH-X00, HIFIMAN HEXX
Mixing: RME Fireface UFX->Reaper/Izotope->Yamaha HS8

 

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