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can i use a 12 volt battery on a 9 volt device ?

 
 
hhgggff
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      07-11-2009
My friends dad is building a Tardis for his grandson.

We have rigged up the blue flashing light using a 12 volt car battery, we
now need to sort out the sounds.

I was thinking of using an old cars cassette tape, but I have an old 9 volt
portable cassette handy.

Will it burn down the TARDIS if I use that instead ?

tafankuverymuch

 
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ian field
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      07-11-2009

"hhgggff" <(E-Mail Removed)> wrote in message
newso16m.54775$(E-Mail Removed) om...
> My friends dad is building a Tardis for his grandson.
>
> We have rigged up the blue flashing light using a 12 volt car battery, we
> now need to sort out the sounds.
>
> I was thinking of using an old cars cassette tape, but I have an old 9
> volt portable cassette handy.
>
> Will it burn down the TARDIS if I use that instead ?
>
> tafankuverymuch
>


You can get simple to use regulator chips that drop the voltage down, you
only need a couple of components to make a working voltage regulator. Ask on
News:sci.electronics.basic - the folk on there are usually very helpful and
should explain all you need.


 
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doS
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Posts: n/a
 
      07-11-2009
you can only jump a few more lightyears with 12 volt.

"hhgggff" <(E-Mail Removed)> wrote in message
newso16m.54775$(E-Mail Removed) om...
> My friends dad is building a Tardis for his grandson.
>
> We have rigged up the blue flashing light using a 12 volt car battery, we
> now need to sort out the sounds.
>
> I was thinking of using an old cars cassette tape, but I have an old 9
> volt portable cassette handy.
>
> Will it burn down the TARDIS if I use that instead ?
>
> tafankuverymuch
>


 
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chuckcar
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Posts: n/a
 
      07-11-2009
"hhgggff" <(E-Mail Removed)> wrote in
newso16m.54775$(E-Mail Removed) om:

> My friends dad is building a Tardis for his grandson.
>
> We have rigged up the blue flashing light using a 12 volt car battery,
> we now need to sort out the sounds.
>
> I was thinking of using an old cars cassette tape, but I have an old 9
> volt portable cassette handy.
>
> Will it burn down the TARDIS if I use that instead ?
>

The tape motor will run at the wrong speed for one. What you need is a
voltage regulator. A 7809 should do the trick. The 7800 series convert DC
voltages. Granted a transformer does it, but these handle *much* wider
voltage inputs and are tiny in comparison. A 7812 hooked to the +12v
connection with the other connection hooked to a 200 microfarad capacitor
should give you a rock solid +9v out. You'll need a piece of breadboard
about 1" square to mount these on.

http://en.wikipedia.org/wiki/78xx

--
(setq (chuck nil) car(chuck) )
 
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ian field
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      07-11-2009

"chuckcar" <(E-Mail Removed)> wrote in message
news:Xns9C459893424AFchucknilcar@127.0.0.1...
> "hhgggff" <(E-Mail Removed)> wrote in
> newso16m.54775$(E-Mail Removed) om:
>
>> My friends dad is building a Tardis for his grandson.
>>
>> We have rigged up the blue flashing light using a 12 volt car battery,
>> we now need to sort out the sounds.
>>
>> I was thinking of using an old cars cassette tape, but I have an old 9
>> volt portable cassette handy.
>>
>> Will it burn down the TARDIS if I use that instead ?
>>

> The tape motor will run at the wrong speed for one. What you need is a
> voltage regulator. A 7809 should do the trick. The 7800 series convert DC
> voltages. Granted a transformer does it, but these handle *much* wider
> voltage inputs and are tiny in comparison. A 7812 hooked to the +12v
> connection with the other connection hooked to a 200 microfarad capacitor
> should give you a rock solid +9v out. You'll need a piece of breadboard
> about 1" square to mount these on.
>


You should read up on a subject you know little about before giving advice
to others.

Even in older cassette recorders the motors had centrifugal speed governors
and modern ones have an IC speed controller (otherwise they'd run slower and
slower as the battery was used).

Your mention of transformers is misleading, without a "chopper" circuit to
convert DC into AC a transformer will burn out.

The OP is best advised to ask people who are equipped to give accurate
advice, such as the folk on News:sci.electronics.basics .


 
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chuckcar
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Posts: n/a
 
      07-11-2009
"ian field" <(E-Mail Removed)> wrote in
news:VZ56m.172$(E-Mail Removed)2:

>
> "chuckcar" <(E-Mail Removed)> wrote in message
> news:Xns9C459893424AFchucknilcar@127.0.0.1...
>> "hhgggff" <(E-Mail Removed)> wrote in
>> newso16m.54775$(E-Mail Removed) om:
>>
>>> My friends dad is building a Tardis for his grandson.
>>>
>>> We have rigged up the blue flashing light using a 12 volt car battery,
>>> we now need to sort out the sounds.
>>>
>>> I was thinking of using an old cars cassette tape, but I have an old 9
>>> volt portable cassette handy.
>>>
>>> Will it burn down the TARDIS if I use that instead ?
>>>

>> The tape motor will run at the wrong speed for one. What you need is a
>> voltage regulator. A 7809 should do the trick. The 7800 series convert
>> DC voltages. Granted a transformer does it, but these handle *much*
>> wider voltage inputs and are tiny in comparison. A 7812 hooked to the
>> +12v connection with the other connection hooked to a 200 microfarad
>> capacitor should give you a rock solid +9v out. You'll need a piece of
>> breadboard about 1" square to mount these on.
>>

>
> You should read up on a subject you know little about before giving
> advice to others.
>

Considering the fact that my post is *far* more detailed than yours,
you're hardly a person to make such a judgement = along with your errors
detaied below.

> Even in older cassette recorders the motors had centrifugal speed
> governors and modern ones have an IC speed controller (otherwise they'd
> run slower and slower as the battery was used).
>

And none of this would burn out with 1 1/3 times the voltage input?
dubious.

> Your mention of transformers is misleading, without a "chopper" circuit
> to convert DC into AC a transformer will burn out.
>

He's *using* a DC power source - a car battery. So a rectifier circuit or
an analogue is completely unncessary

> The OP is best advised to ask people who are equipped to give accurate
> advice, such as the folk on News:sci.electronics.basics .
>

One *minor* correction of my post however - that *should* have been a 7809
not a 7812. This I picked up immediately when I read your reply. A pretty basic
error you didn't even notice. a 7812 converts *to* 12v whereas a 7809 converts
to 5v. Hence their names.

--
(setq (chuck nil) car(chuck) )
 
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rf
Guest
Posts: n/a
 
      07-12-2009

"chuckcar" <(E-Mail Removed)> wrote in message
news:Xns9C45B2F782332chucknilcar@127.0.0.1...

> A pretty basic error you didn't even notice.


> a 7812 converts *to* 12v whereas a 7809 converts
> to 5v. Hence their names.


5V?

ROFL


 
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chuckcar
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Posts: n/a
 
      07-12-2009
"rf" <(E-Mail Removed)> wrote in
news:3zc6m.4396$(E-Mail Removed):

>
> "chuckcar" <(E-Mail Removed)> wrote in message
> news:Xns9C45B2F782332chucknilcar@127.0.0.1...
>
>> A pretty basic error you didn't even notice.

>
>> a 7812 converts *to* 12v whereas a 7809 converts
>> to 5v. Hence their names.

>
> 5V?
>

Yeah. 9v of course. dammit janet.




--
(setq (chuck nil) car(chuck) )
 
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Walter Bushell
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Posts: n/a
 
      07-12-2009
In article <Xns9C45B2F782332chucknilcar@127.0.0.1>,
chuckcar <(E-Mail Removed)> wrote:

> "ian field" <(E-Mail Removed)> wrote in
> news:VZ56m.172$(E-Mail Removed)2:
>
> >
> > "chuckcar" <(E-Mail Removed)> wrote in message
> > news:Xns9C459893424AFchucknilcar@127.0.0.1...
> >> "hhgggff" <(E-Mail Removed)> wrote in
> >> newso16m.54775$(E-Mail Removed) om:
> >>
> >>> My friends dad is building a Tardis for his grandson.
> >>>
> >>> We have rigged up the blue flashing light using a 12 volt car battery,
> >>> we now need to sort out the sounds.
> >>>
> >>> I was thinking of using an old cars cassette tape, but I have an old 9
> >>> volt portable cassette handy.
> >>>
> >>> Will it burn down the TARDIS if I use that instead ?
> >>>
> >> The tape motor will run at the wrong speed for one. What you need is a
> >> voltage regulator. A 7809 should do the trick. The 7800 series convert
> >> DC voltages. Granted a transformer does it, but these handle *much*
> >> wider voltage inputs and are tiny in comparison. A 7812 hooked to the
> >> +12v connection with the other connection hooked to a 200 microfarad
> >> capacitor should give you a rock solid +9v out. You'll need a piece of
> >> breadboard about 1" square to mount these on.
> >>

> >
> > You should read up on a subject you know little about before giving
> > advice to others.
> >

> Considering the fact that my post is *far* more detailed than yours,
> you're hardly a person to make such a judgement = along with your errors
> detaied below.
>
> > Even in older cassette recorders the motors had centrifugal speed
> > governors and modern ones have an IC speed controller (otherwise they'd
> > run slower and slower as the battery was used).
> >

> And none of this would burn out with 1 1/3 times the voltage input?
> dubious.
>
> > Your mention of transformers is misleading, without a "chopper" circuit
> > to convert DC into AC a transformer will burn out.
> >

> He's *using* a DC power source - a car battery. So a rectifier circuit or
> an analogue is completely unncessary
>
> > The OP is best advised to ask people who are equipped to give accurate
> > advice, such as the folk on News:sci.electronics.basics .
> >

> One *minor* correction of my post however - that *should* have been a 7809
> not a 7812. This I picked up immediately when I read your reply. A pretty
> basic
> error you didn't even notice. a 7812 converts *to* 12v whereas a 7809
> converts
> to 5v. Hence their names.


Two resistors tapped between them should do the trick and limit current.
 
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hhgggff
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      07-12-2009
I will look into a voltage regulator but will probably just get an old car
stereo as it's easier

tafankuverymuch

 
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