### Network

S

#### [email protected]

Jan 1, 1970
0
Does anyone not reading my other thread have any ideas what the power
drain would be for a very small radio?

I basically want an audible noise for as few milliwatts as possible,
and run from a 12V lead acid battery.

TIA jack

J

#### Jonathan Kirwan

Jan 1, 1970
0
Does anyone not reading my other thread have any ideas what the power
drain would be for a very small radio?

I basically want an audible noise for as few milliwatts as possible,
and run from a 12V lead acid battery.

The 'few mW as possible' and 'noise' suggests to me - piezo. A lot of
them are spec'd for 12V, too. I think 5mA (maybe a little more) would
be typical. So 60mW, roughly speaking. I think a custom design would
be able to do better on power consumption -- but those figures are for
off-the-shelf and very cheap designs (about $1.) Jon S #### [email protected] Jan 1, 1970 0 The 'few mW as possible' and 'noise' suggests to me - piezo. A lot of them are spec'd for 12V, too. I think 5mA (maybe a little more) would be typical. So 60mW, roughly speaking. I think a custom design would be able to do better on power consumption -- but those figures are for off-the-shelf and very cheap designs (about$1.)

Jon

Wow, thanks Jon.
That's going to make things a lot less expensive and complicated.
I could buy two, one for a spare
Any ideas what they would be called and what sort of outlets would
sell these? I will try a google search for Australia.
Thanks, jack

H

#### Homer J Simpson

Jan 1, 1970
0
Wow, thanks Jon.
That's going to make things a lot less expensive and complicated.
I could buy two, one for a spare
Any ideas what they would be called and what sort of outlets would
sell these? I will try a google search for Australia.
Thanks, jack

If you want to hear it I'd avoid piezo. Also, a bigger speaker will draw
less power for a given sound output.

S

#### [email protected]

Jan 1, 1970
0
If you want to hear it I'd avoid piezo. Also, a bigger speaker will draw
less power for a given sound output.

Thanks again Homer.
All I can find so far are piezo earphones for crystal sets.
Interesting about the big speakers. I've got plenty of them. Does the
impedance affect the efficiency?

To be honest, all I want is a bit of noise audible at the front door,
that gives the impression of someone being home. A crystal set that
received several close stations would be fine, and whatever speaker I
used I would tape to a panel of the front door to act as a sound
board. Afterall, no-one will be listening to the information or music,
and especially not inside the house

I thought I read somewhere about piezo being augmented with a horn.
Perhaps attached to my door panel? If I can get some 24/7 noise with
10 mA, I could run the thing for 4 weeks from a 12Ah battery with NO
charging. So any charging would be cream on the jam, so to speak.

Thanks again, jack

J

#### Jonathan Kirwan

Jan 1, 1970
0
Wow, thanks Jon.
That's going to make things a lot less expensive and complicated.
I could buy two, one for a spare

Well, someone else thinks piezo are hard to hear. They use them in
fire alarms a lot, so I have to disagree a bit on that point. However,
they are higher freq (3kHz to 4kHz area) and if you have hearing
troubles at high freqs, then they may be dampened a bit. Ambient
environment can also make or break this.
Any ideas what they would be called and what sort of outlets would
sell these? I will try a google search for Australia.

They are called piezo alarms or buzzers. You need to be a bit
careful, though. Some piezos are sold without the driver circuit,
depending instead on you fabricating one. Those will be the really
cheap ones. You want those that are ready to go, I guess. Go to
www.digikey.com and enter 'piezo' in the search. Then look down for
'buzzers' and click that. You can then select frequencies or current
draw, etc. and do a further search. Or google these three words,
piezo buzzer 12V. That will get you some web sites to examine,
selling them.

Jon

S

#### [email protected]

Jan 1, 1970
0
Well, someone else thinks piezo are hard to hear. They use them in
fire alarms a lot, so I have to disagree a bit on that point. However,
they are higher freq (3kHz to 4kHz area) and if you have hearing
troubles at high freqs, then they may be dampened a bit. Ambient
environment can also make or break this.

They are called piezo alarms or buzzers. You need to be a bit
careful, though. Some piezos are sold without the driver circuit,
depending instead on you fabricating one. Those will be the really
cheap ones. You want those that are ready to go, I guess. Go to
www.digikey.com and enter 'piezo' in the search. Then look down for
'buzzers' and click that. You can then select frequencies or current
draw, etc. and do a further search. Or google these three words,
piezo buzzer 12V. That will get you some web sites to examine,
selling them.

Jon

Thanks Jon, I think I may have misled you with my term "noise". I
really want the noise of habitation. Music, voices etc. An LED light
will come on at dusk and go off at dawn, and 24/7 I want the sound of
a muffled radio to be audible from inside the house.

At present, I'm leaning towards a simple crystal set tuner with a half
watt amplifier kit driving a large speaker?

Any suggestions towards simplicity, cheapness, and above all, sound
power to electrical power efficiency will be most helpful.

Thanks, jack

H

#### Homer J Simpson

Jan 1, 1970
0
Thanks again Homer.
All I can find so far are piezo earphones for crystal sets.
Interesting about the big speakers. I've got plenty of them. Does the
impedance affect the efficiency?

Genrally no.
To be honest, all I want is a bit of noise audible at the front door,
that gives the impression of someone being home.

A piezo type would be fine for that.

H

#### Homer J Simpson

Jan 1, 1970
0
Thanks Jon, I think I may have misled you with my term "noise". I
really want the noise of habitation. Music, voices etc. An LED light
will come on at dusk and go off at dawn

Won't fool the determined. Some alarm stickers on the doors and windows work
better. A flickering blue light looks like a TV.

--
..

--
..
..
..
..
..
..
..
..

--

S

#### [email protected]

Jan 1, 1970
0
Won't fool the determined. Some alarm stickers on the doors and windows work
better. A flickering blue light looks like a TV.

Thanks Homer
The determined will get in anywhere, but one must ask why they would
be determined to break into a crappy old house amongst thousands of
mansions.

that you have got something to protect.

The flickering blue light is pure genius. I wonder if there is a
flickering LED array that could simulate a TV. That should be easy and
cheap to incorporate. Thanks again, jack

M

#### Michael A. Terrell

Jan 1, 1970
0
Thanks Homer
The determined will get in anywhere, but one must ask why they would
be determined to break into a crappy old house amongst thousands of
mansions.

that you have got something to protect.

The flickering blue light is pure genius. I wonder if there is a
flickering LED array that could simulate a TV. That should be easy and
cheap to incorporate. Thanks again, jack

Stickers are useless, unless the stickers are from a local alarm
company. Lots of places with those cheap, generic flea market stickers
get hit. In fact, its an advertisement that the owner has something
worth stealing, but is too damn cheap to buy real protection.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

H

#### Homer J Simpson

Jan 1, 1970
0
that you have got something to protect.

It eliminates the smash in idiots. They prefer to try elsewhere. Another tip
is to find the biggest dog dish you can, bash it up so it looks well chewed,
and write Tiny on the side with a marker.

C

#### Chris

Jan 1, 1970
0
Does anyone not reading my other thread have any ideas what the power
drain would be for a very small radio?

I basically want an audible noise for as few milliwatts as possible,
and run from a 12V lead acid battery.

TIA jack

Hi, Jack. The power requirement for your radio is going to be
apart from that will be much less. An older 9V transistor radio I
built many moons ago had a current draw with the sound turned all the
way down of 30mA or so. That would be around 250mW, much less than
the power required to drive the speaker loud enough to hear outside.
Thatw ill probably take a few watts, at least. With the efficiency of
audio outputs in general, you can depend on several watts consumed to
get two or three watts at the speaker. Even with a DC-to-DC
converter, that will mean around a 1/2A current draw from your
battery.

Many small radios (particularly those that operate on 9VDC) have
provision for an external car cigarette lighter adapter, allowing them
to run directly off 12VDC. You also might want to look into this --
it would be less hassle than a DC-to-DC converter, and you won't have
to worry about electrical noise from the converter causing problems.

I'd also recommend looking into a 12VDC marine battery, if you're
discharge, and can put out the 1/4 to 1/2A you'll need (even with a DC-
to-DC converter) for a longer time than an automotive battery.

Good luck
Chris

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