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Kids' "crystal radio", making an amplifier thereof

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
Reply to
Ignoramus16919
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LM386 is an easy audio amplifier. Google the part number to find data sheets and circuit ideas.

- mkaras

Reply to
mkaras

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

i
Reply to
Ignoramus16919

Here's another idea...

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Haven't built it myself, but it looks like it should work...

Miguel

Reply to
mfo

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Reply to
Homer J Simpson

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

Reply to
Michael Black

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.

Reply to
Stanislaw Flatto

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

RL

Reply to
legg

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

Reply to
mrdarrett

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... :-)

Reply to
Kryten

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

i
Reply to
Ignoramus16919

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

i
Reply to
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.

Reply to
randyfromm

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

Reply to
Marc Guardiani

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

Reply to
Michael Black

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

i
Reply to
Ignoramus16919

ZN414/5, MK484

Reply to
GPG

Not bad. A long horizontal is usually preferred.

Reply to
Homer J Simpson

Sure, but for $10 you can get a whole kit that will work.

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Reply to
Homer J Simpson

Then it's not a crystal radio.

Michael

Reply to
Michael Black

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