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Kids' "crystal radio", making an amplifier thereof

I

Ignoramus16919

My 5 year old son is building (with my help) a "crystal radio", which
is a air core tuning coil, a diode, and a earphone. It is a cheap
chinese kit.

As the instructions allude to, it is kinda hard to get out of this
thing enough power to really hear anything. They talk about trying to
touch "cold water faucet" with one end for better pickup, etc etc etc.

So, I think, it would be great to make an amplifier that would amplify
the sound enough to hear it well.

Also, if I make my own amplifier for that thing, my son's respect for
me will know no bounds.

I generally know enough to use a soldering iron and have some pieces,
though I do not have simple amplifiers -- but I could order one from
digikey if push comes to shove.

I would use a small battery for power, or some power supplies.

What is the easiest and most idiot proof to amplify output from that
tuning coil to make this into a working radio. Ability to power a
small speaker would be another plus.

i
 
M

mkaras

Ignoramus16919 said:
My 5 year old son is building (with my help) a "crystal radio", which
is a air core tuning coil, a diode, and a earphone. It is a cheap
chinese kit.

As the instructions allude to, it is kinda hard to get out of this
thing enough power to really hear anything. They talk about trying to
touch "cold water faucet" with one end for better pickup, etc etc etc.

So, I think, it would be great to make an amplifier that would amplify
the sound enough to hear it well.

Also, if I make my own amplifier for that thing, my son's respect for
me will know no bounds.

I generally know enough to use a soldering iron and have some pieces,
though I do not have simple amplifiers -- but I could order one from
digikey if push comes to shove.

I would use a small battery for power, or some power supplies.

What is the easiest and most idiot proof to amplify output from that
tuning coil to make this into a working radio. Ability to power a
small speaker would be another plus.

i
Click to expand...

LM386 is an easy audio amplifier. Google the part number to find data
sheets and circuit ideas.

- mkaras
 
I

Ignoramus16919

LM386 is an easy audio amplifier. Google the part number to find data
sheets and circuit ideas.
Click to expand...

OK, sounds good enough, I will try right away, and will check my home
pile as well. Thanks.

i
 
M

Michael Black

Ignoramus16919 said:
My 5 year old son is building (with my help) a "crystal radio", which
is a air core tuning coil, a diode, and a earphone. It is a cheap
chinese kit.

As the instructions allude to, it is kinda hard to get out of this
thing enough power to really hear anything. They talk about trying to
touch "cold water faucet" with one end for better pickup, etc etc etc.

So, I think, it would be great to make an amplifier that would amplify
the sound enough to hear it well.
Click to expand...
This is not a design question.

It belongs in sci.electronics.basics

That said, the insensitivity is because there's no radio frequency
amplification. It relies on having a long antenna to get a relatively
strong signal into the diode detector. Unless you get a strong signal
there, you aren't likely to be happy with the results.

An audio amplifier will just make a useable signal stronger, so you
can drive a speaker.

Michael
 
S

Stanislaw Flatto

Ignoramus16919 said:
My 5 year old son is building (with my help) a "crystal radio", which
is a air core tuning coil, a diode, and a earphone. It is a cheap
chinese kit.

As the instructions allude to, it is kinda hard to get out of this
thing enough power to really hear anything. They talk about trying to
touch "cold water faucet" with one end for better pickup, etc etc etc.

So, I think, it would be great to make an amplifier that would amplify
the sound enough to hear it well.

Also, if I make my own amplifier for that thing, my son's respect for
me will know no bounds.

I generally know enough to use a soldering iron and have some pieces,
though I do not have simple amplifiers -- but I could order one from
digikey if push comes to shove.

I would use a small battery for power, or some power supplies.

What is the easiest and most idiot proof to amplify output from that
tuning coil to make this into a working radio. Ability to power a
small speaker would be another plus.

i
Click to expand...
OK, you asked for it!!!
This is "design" congregation, so you get responses for a "project".
What about just looking deep under your junk pile and pull out some
discarded transistor radio (can even be just AM band) the size of Camel
cigarettes package and use the _included_ audio stage and speaker.
It may need new set of batteries.

Have fun

Stanislaw
Slack user from Ulladulla.
 
L

legg

This is not a design question.

It belongs in sci.electronics.basics

That said, the insensitivity is because there's no radio frequency
amplification. It relies on having a long antenna to get a relatively
strong signal into the diode detector. Unless you get a strong signal
there, you aren't likely to be happy with the results.
Click to expand...

And a good ground - don't poo-poo the water faucet reference.

RL
 
M

[email protected]

Stanislaw said:
OK, you asked for it!!!
This is "design" congregation, so you get responses for a "project".
What about just looking deep under your junk pile and pull out some
discarded transistor radio (can even be just AM band) the size of Camel
cigarettes package and use the _included_ audio stage and speaker.
It may need new set of batteries.

Have fun

Stanislaw
Slack user from Ulladulla.
Click to expand...


Oh that's mean. That's a bit like powering a wind turbine alternator
coil with power from the coal power plant down the street...

Michael
 
K

Kryten

My dad tried to build a crystal set with me, and it was an abysmal failure.

My dad knew less than I did, and the guy at the electronics store told my
dad that the TV aerial would do the job. Which it won't because there is
only a short length of metal picking up anything. It might work for an
amplified radio, but not a crystal set.

You will need a BIG length of wire for an aerial (tens of metres
preferably), a strong AM radio signal, and a good earth. I'm not sure if
they still transmit AM radio strong enough to be heard on anything as deaf
as a crystal set.

Though I am now working on the latest digital radio phone technology, I
never got an analogue radio working. Though I did save the crystal set
parts. Maybe I shall get it working one day, just to prove I can... :)
 
I

Ignoramus16919

This is not a design question.

It belongs in sci.electronics.basics

That said, the insensitivity is because there's no radio frequency
amplification. It relies on having a long antenna to get a relatively
strong signal into the diode detector. Unless you get a strong signal
there, you aren't likely to be happy with the results.

An audio amplifier will just make a useable signal stronger, so you
can drive a speaker.
Click to expand...

Makes sense, is there something simple to amplify the RF signal?

i
 
I

Ignoramus16919

My dad tried to build a crystal set with me, and it was an abysmal failure.

My dad knew less than I did, and the guy at the electronics store told my
dad that the TV aerial would do the job. Which it won't because there is
only a short length of metal picking up anything. It might work for an
amplified radio, but not a crystal set.

You will need a BIG length of wire for an aerial (tens of metres
preferably), a strong AM radio signal, and a good earth. I'm not sure if
they still transmit AM radio strong enough to be heard on anything as deaf
as a crystal set.

Though I am now working on the latest digital radio phone technology, I
never got an analogue radio working. Though I did save the crystal set
parts. Maybe I shall get it working one day, just to prove I can... :)
Click to expand...

OK... Are there any modern parts under $5 that could make this work
satisfactorily?

i
 
R

[email protected]

All this talk of amplifiers misses the point of this project entirely.
The FUN is in that it uses NO electricity other than that from the
antenna.

All are correct who say "long antenna and good ground." Even if you
don't have a 50,000 watt radio station nearby, you'll receive something
if the thing is built correctly.
 
M

Marc Guardiani

Kryten said:
You will need a BIG length of wire for an aerial (tens of metres
preferably), a strong AM radio signal, and a good earth. I'm not sure if
they still transmit AM radio strong enough to be heard on anything as deaf
as a crystal set.
Click to expand...

Living in the Pittsburgh, PA area, about a mile from KDKA's 50kW AM
transmitter, made building a crystal radio trivial. I don't recall even
needing an antenna. Of course my programming was limited to KDKA and
one other station :).

Marc
 
M

Michael Black

Marc Guardiani" ([email protected]) said:
Living in the Pittsburgh, PA area, about a mile from KDKA's 50kW AM
transmitter, made building a crystal radio trivial. I don't recall even
needing an antenna. Of course my programming was limited to KDKA and
one other station :).

Marc
Click to expand...

Of course, the real issue is getting a strong signal into the diode.

You can do that with the long antenna, or moving next to the radio
station.

Michael
 
I

Ignoramus16919

All this talk of amplifiers misses the point of this project entirely.
The FUN is in that it uses NO electricity other than that from the
antenna.

All are correct who say "long antenna and good ground." Even if you
don't have a 50,000 watt radio station nearby, you'll receive something
if the thing is built correctly.
Click to expand...

Would, say, 10 meters of vertical wire work for an antenna?

i
 
G

GPG

Michael said:
Of course, the real issue is getting a strong signal into the diode.

You can do that with the long antenna, or moving next to the radio
station.

Michael
Click to expand...
ZN414/5, MK484
 
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