I would like some suggestions on how to complete this crystal radio project I bought

Thread Starter

LifeFlow

Joined May 4, 2020
8
I recently signed up as a new member on All About Circuits and I hope that I will be able to contribute to this website and the forums as well as learn a lot about electronics in general. I am (currently) a soldering and electronics amateur though I believe that will change in the future.

I have several questions about the crystal radio project I am working on and if they are answered hopefully I should be able to complete this project. I hope I am posting my questions about this project in the right place but if I am not please let me know. I will upload some files to show how much progress I have made on the project so far including pictures of the soldering, schematics etc. Since I am still learning how to solder, if you have some suggestions on how I could have soldered the project better feel free to tell me, but overall go easy on me in terms of the quality of my soldering work :).

I think I soldered most of the components into the correct places (the outlines on the board made it fairly straightforward) though I am iffy about some of them. I am fairly sure I soldered the variable capacitor the right way up but if I haven't please let me know. I am particularly unsure about some components such as the earphone jack; did I solder its leads into the correct holes? Also I am uncertain if I soldered the ends of the antenna coil correctly.

In particular I wasn't sure about how to ground the crystal radio; do I need to solder a copper wire to the big unused hole on the PCB? And then attach that wire to some sort of metal pipe driven into the ground? Is that even necessary? Components for grounding was the only thing that wasn't included with the project so I want to confirm how to ground the project and what components I will need. By the way I would ideally like to not ground the project outdoors so if you have any suggestions for how I can complete the project and use it only indoors please let me know. Any other general comments about completing this project would be great too.

Thanks, and I look forward to your replies!
 

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Tonyr1084

Joined Sep 24, 2015
4,539
Welcome to AAC.

With regards your soldering, it looks fairly good; but it's hard to tell from a photograph. The ground plane should be grounded either to earth or something metal and fairly large. The solder there is overly heavy. It's probably intended to be screwed to something with a wire attached. You can use the household ground IF it's properly grounded. If not - it could present a shock hazard. Otherwise, a copper water pipe somewhere in the house will serve as a good ground without the shock hazard. Hopefully.

It looks like you've put things in their proper place and orientation. I'm guessing you haven't tried connecting it yet. If you did you'd have probably reported a problem. As for the jack - I can't tell for sure, but my first guess is that it shouldn't matter. Hopefully.

Nevertheless, since the board is not powered you're not risking damaging anything. Not unless you've over heated the solder joints to the point of radiating heat into a component. The thing I'd be most concerned about would be the diode. The rest of the components should tolerate heat fairly well.

Don't know if this answers your questions. Feel free to post further questions if you need.
 

vu2nan

Joined Sep 11, 2014
148
Nice soldering job!

You would need to first cut off the extra antenna coil wire ends and diode leads.

A 60 foot length of wire going vertically up and horizontally out should be okay for an antenna.

A metallic water pipe going underground should make a good ground.

Have fun!

- Nandu.
 

MrChips

Joined Oct 2, 2009
21,143
The truth is, you don't need all those fancy components to build your basic crystal radio.

Here is what you need:

1) A germanium diode such as 1N34
2) High impedance earpiece
3) A long wire aerial
4) Connection to a ground pipe

Connect the diode between the aerial and ground connection.
Connect the earpiece in parallel across the diode.

Granted, you will pick up every MW/AM radio station nearby and you wouldn't be able to select just one station.
At least this will get you started on your discovery of the wonderful world of crystal radio building and listening.
 

Thread Starter

LifeFlow

Joined May 4, 2020
8
Welcome to AAC.

With regards your soldering, it looks fairly good; but it's hard to tell from a photograph. The ground plane should be grounded either to earth or something metal and fairly large. The solder there is overly heavy. It's probably intended to be screwed to something with a wire attached. You can use the household ground IF it's properly grounded. If not - it could present a shock hazard. Otherwise, a copper water pipe somewhere in the house will serve as a good ground without the shock hazard. Hopefully.

It looks like you've put things in their proper place and orientation. I'm guessing you haven't tried connecting it yet. If you did you'd have probably reported a problem. As for the jack - I can't tell for sure, but my first guess is that it shouldn't matter. Hopefully.

Nevertheless, since the board is not powered you're not risking damaging anything. Not unless you've over heated the solder joints to the point of radiating heat into a component. The thing I'd be most concerned about would be the diode. The rest of the components should tolerate heat fairly well.

Don't know if this answers your questions. Feel free to post further questions if you need.
Thanks for your reply.

I might see if I can find a screw that is the correct size for the hole and then attach some sort of wire to it, then ground it. Would I need to solder the screw to the hole or is placing it inside the hole enough?
 

Thread Starter

LifeFlow

Joined May 4, 2020
8
If you have Copper water pipes coming into your house use that as the Earth signal otherwise you can use an Earth spike outside...as for an Aerial a long wire will do..
I already soldered what I think was an aerial to the board; it was an insulated wire about a foot long that was included with the kit. I looked back at the photos I uploaded and realised that it was kind of hidden from view, sorry. Thanks for the reply.
 

Thread Starter

LifeFlow

Joined May 4, 2020
8
You should snip off the long wire ends underneath the board.
Thanks, I was going to do that once I was sure I had everything in the correct position; otherwise if I had to change the position of some things I figured keeping the leads longer especially for the parts I wasn't sure of would make it easier.
 

Thread Starter

LifeFlow

Joined May 4, 2020
8
Nice soldering job!

You would need to first cut off the extra antenna coil wire ends and diode leads.

A 60 foot length of wire going vertically up and horizontally out should be okay for an antenna.

A metallic water pipe going underground should make a good ground.

Have fun!

- Nandu.
Thanks, I liked my soldering job too :). Not too bad for a beginner. Like I said to AlbertHall I wanted to make sure everything was in place first before I cut off the extra leads. Do you really need a 60 foot wire for a project like this? That seems really long.
 

Thread Starter

LifeFlow

Joined May 4, 2020
8
The truth is, you don't need all those fancy components to build your basic crystal radio.

Here is what you need:

1) A germanium diode such as 1N34
2) High impedance earpiece
3) A long wire aerial
4) Connection to a ground pipe

Connect the diode between the aerial and ground connection.
Connect the earpiece in parallel across the diode.

Granted, you will pick up every MW/AM radio station nearby and you wouldn't be able to select just one station.
At least this will get you started on your discovery of the wonderful world of crystal radio building and listening.
It is amazing to me how few components you need to make a crystal radio. I was looking at some videos on youtube about making crystal radios like:
and
and the second video in particular was so incredible to me it may as well have been magic :) . Thanks.
 

vu2nan

Joined Sep 11, 2014
148
Thanks, I liked my soldering job too :). Not too bad for a beginner. Like I said to AlbertHall I wanted to make sure everything was in place first before I cut off the extra leads. Do you really need a 60 foot wire for a project like this? That seems really long.
The longer, the better for a crystal radio antenna! A 60 foot wire would be the bare minimum.

- Nandu.
 

Thread Starter

LifeFlow

Joined May 4, 2020
8
I uploaded my photos in PDF form as suggested in the "Please Read ..." post for the General Electronics forum. I was browsing through several posts in the forum and noticed a lot of people don't do that; they seem to just upload pics in jpeg or png form. Anyone know why it is important to upload photos in PDF form or does it not make much of a difference?
 

MrChips

Joined Oct 2, 2009
21,143
You also do not need a fancy printed circuit board in order to build and experiment with crystal radio circuits.

You will need the following for construction:

1) small scrap piece of softwood, about 4 x 6 x ½"
2) small #6 3/8" pan-head wood screws
3) #6 flat washers
4) the cardboard inner-tube from a spent roll of toilet paper

The electrical items you will need:

1) 1N34 or 1N34A diode
2) Ceramic earphone or high-impedance headset
3) 350pF variable capacitor salvaged from an old radio
4) 22-26 gauge enamel coated copper wire

1588943632837.png
 

Tonyr1084

Joined Sep 24, 2015
4,539
Would I need to solder the screw to the hole or is placing it inside the hole enough?
Simple screw - flat washer - through the board - the wire or ring terminal if you want to get fancy - another flat washer - maybe a lock washer - a nut. No need to solder. As long as the screw is making good contact with the circuit board. You COULD forego the first flat washer and use an internal tooth star washer. It will bite into the copper (or solder in your case) and improve connection.
 
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