Topic: 5V Battery

[blu666z]

I have had fun making the battery system for my UA-5.  Now I want to try and make another to run my MD which uses 5V.  I was talking to Daryan about this and he said I might be able to use a 6V battery and a voltage regulator.  How hard would that be to do?  I was thinking a could build two cables to run off the same 6V batteries, one for my MD(5V) and one for my D7(6V).

-Kevin

[Brian Skalinder]

I have had fun making the battery system for my UA-5.  Now I want to try and make another to run my MD which uses 5V.  I was talking to Daryan about this and he said I might be able to use a 6V battery and a voltage regulator.  How hard would that be to do?  I was thinking a could build two cables to run off the same 6V batteries, one for my MD(5V) and one for my D7(6V).

Most VRs require a 3+ voltage differential between incoming and outgoing voltage, so...a VR probably won't do the trick.  I've read on the Oade board that you can just hook up a couple diodes in-line to the hot wire to drop the 6v to 5v.  Never done it and don't know more details than that, though.

[blu666z]

I need to stop by Rat Shack on the way home anyway for some heat shrink.  Guess I'll quiz them about that also.

-Kevin

[blu666z]

Most VRs require a 3+ voltage differential between incoming and outgoing voltage, so...a VR probably won't do the trick.  I've read on the Oade board that you can just hook up a couple diodes in-line to the hot wire to drop the 6v to 5v.  Never done it and don't know more details than that, though.

So could I do the VR thing with a 9.6v then?

-Kevin

[Brian Skalinder]

So could I do the VR thing with a 9.6v then?

Yup, that should work.

[blu666z]

Do you happen to know any links to plans?  Computer programming I can handle, but electricity is some I am fairly ignorant on.

-Kevin

[Brian Skalinder]

If you made your battery pack, you can do this - it's easy.  It'll look like this:

1  2  3

|  |  |  
|__|__|
|     |
| [ ] |
|_____|

 

1 = (+) input  (in from your 9.6v RC battery)
2 = (-) ground (in from your 9.6v RC battery)
3 = (+) output (out to your MD)

The VR dissipates the extra voltage as heat, so you may want a small heat sink - not sure if it's absolutely necessary, but it certainly couldn't hurt.  It's also a good idea to use shrink tubing around each of the pins/solder connections.

You should be able to get a 7805 5v output voltage regulator at RS.  When they pull it up on the inventory computer, it should reference a heat sink and some contact paste that goes with it.  You just put contact paste on the base of the heat sink and then screw the heat sink and VR together.  It's a no brainer.

Hope this helps!

[blu666z]

Damn you can do some crazy shit with just a bunch of dashes.  +T.  It looks like it will be Sunday before I can do this.  Thanks for the help.  Looks like I will need to get a soldiering iron to do this one.

-Kevin

[blu666z]

My MD is pulling 5V 800mAH.  How does the difference in voltage come in to play as far as how long it will run off a 9.6V 1600mAH battery?

-Kevin

[Brian Skalinder]

My MD is pulling 5V 800mAH.  How does the difference in voltage come in to play as far as how long it will run off a 9.6V 1600mAH battery?

The VR should reduce your overall recording time minimally - sorry, I don't know by how much, nor how to calculate it.  I dunno...maybe 5%, probably less?  Total guess.  Best bet is to try it out.

Your MD draws 800 mA?  Sheesh, what a power pig!  Lessee...( battery capacity / current draw ) * 70% = rough run time.  (70% because AH ratings are usually calculated using a 20-hour dissipation, you don't want to completely drain your battery, and the VR will have a small impact)  So...

( 1600 mAH / 800 mA) * .70 = ~1.4 hrs, or ~84min

I didn't realize MDs were suck power hogs!  

[blu666z]

I got 800mAH from the wall wort.  84 minutes sounds about right though.  I can easy switch the battery out, only holds one, when I do a disc flip if I am running regular duracell ultras.  Now the photo lithium are great.  2-3 shows a piece on those suckers.

-Kevin

[Brian Skalinder]

Ahhhhh...gotcha.  The MD probably doesn't actually draw 800 mA, then.  The wallwart spec of 800 mA I believe just indicates that's the max current the wallwart will provide safely.  Sounds like you're all set with you RC battery, then.

Just finished tracking and listening to my Gomez tape from the other night...time for bed!

[blu666z]

If you made your battery pack, you can do this - it's easy.  It'll look like this:

1  2  3

|  |  |  
|__|__|
|     |
| [ ] |
|_____|

 

1 = (+) input  (in from your 9.6v RC battery)
2 = (-) ground (in from your 9.6v RC battery)
3 = (+) output (out to your MD)

Which of the 2 wires to the MD do I put on 3?  The + one, and then the - goes to 2 with the -'s from the battery?.?.?

-Kevin

[Brian Skalinder]

Yes, pins 2 and 3 will go out to your MD.  So pin 2 will have 2 cables attached - the (-) from the battery, and the (-) going to the MD.

Your MD *should* have a female DC power plug (if it doesn't, the rest of this post is meaningless).

You'll hook up a male DC power plug to the battery pack.  DC power plugs have a ring and a tip.  Near the plug, or in the documentation, it should indicate whether the ring is (-) and the tip is (+) or vice versa.  It's usually ring (-), tip (+).  The symbol on the unit usually looks like a dot surrounded by a circle.  The dot represents the pin, the circle represents the ring.

The easiest way is to wire up the following RS cable to your VR:

RS Female Adaptaplug Socket Cable # 273-1740

Then, find the right sized adaptaplug at RS to fit your MD.  I usually take it in and just see which one fits - easier than measuring the inner and outer diameter of the DC plug and trying to match that way.

The adaptaplug just slots right into the cable above - no more soldering.  But check to make sure the polarity is correct!  The adaptaplug can go into the above cable 2 ways - one way will be ring (-), tip (+) and the other will be ring (+) and tip (-).  If you don't have a multimeter, you should get one (they're cheap and easy to use).

The slightly harder way - but sometimes a more secure fit between DC male plug and female receptable on the unit - is to get a higher quality DC plug elsewhere (sorry, don't know which one b/c I don't know which your MD takes) and wire the DC plug directly to the battery cable (again making sure you have ring/tip polarity correct).

When I first learned how to do this, it seemed complicated.  Then I actually did it - it's really easy to do.  Honest!

[blu666z]

I already did all the adaptaplug stuff with my first battey pack.  Simple stuff.  Thanks for the help.  +T

-Kevin