Tag Archives: Crystal Radio Credit Card Receiver

Credit Card Crystal Radio

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Many thanks to SWLing Post contributor, Paul Evans, who shares this article from Hackaday that highlights a crystal radio built completely on a smart chip credit card by Billy Cheung.

Hackaday notes:

This is possible because the smart chip on many credit cards contains a diode. It’s then a simple matter of hooking up the right pads on the credit card to the rest of a crystal radio circuit, and you’re all set. Of course, [Billy] goes the whole hog, building the entire radio on a single credit card. Other cards are cut up to create bobbins for winding coils to form a variable inductor, used to tune the radio. Doing this allows for a much cleaner, thinner design, rather than using a variable capacitor which is comparatively hard to find. Turning the dial allows stations to be tuned in, and with a high impedance earbud hooked up, you’re listening to AM radio. Oh, and don’t forget an antenna!

Cheung documented the whole process and even shares templates via links in the description of his YouTube video.

Many thanks to Paul and Hackaday for sharing this fun project!

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Vance explores credit card and earpiece radios

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Many thanks to SWLing Post reader, Vance, who writes:

You got me hooked on those little credit card sized radio kits from an eBay seller so much that I have bought a few more of his kits. I’ve found them to be so much fun, that I have started looking elsewhere for other tiny radios.

I came across this the other day and while it is not a kit, I was wondering if you or your readers had ever tried them and if so, what your opinions are: http://jdradio.weebly.com/index.html

earpiece-radio

I know it is likely more novelty than performance, but the prices seem ridiculously low for individual buyers.

Also seen here: http://www.centretradegroup.com/Radio.php

I’m not familiar with the earpiece radios in your links. I have read through those sites, though–unfortunately, as I’m sure Vance noted, they lack any in-depth information.

I did a quick Google search and can see that these radios (both the FM and AM versions) have been around for many years–some references go back to 1999.

I imagine the earpiece radio uses the same auto-tuner that became quite popular in the late 90s. Simply press a button and the receiver auto-tunes to the next strong station: no memories and not manual tuning. Indeed, I used to attend trade shows in Europe in the late 90s and several vendors actually gave away branded novelty radios (in a variety of shapes) with a similar tuner.

Readers: Ever use one of these earpiece radios? Please comment!

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Tinkering with the Credit Card Crystal Radio

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Credit-Card-Crystal-Radio-2

A few weeks ago, we published a short post about a credit card crystal radio from an eBay seller in the UK.

I purchased a kit–at $17-18 US shipped, it’s quite a modest investment for what might be a fun little project.

Credit-Card-Crystal-Radio

The crystal radio arrived while I was traveling during Easter break, but my free time has been so (extremely) limited lately, I was only able to unpack and try out this new arrival yesterday.

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The biggest surprise for me was the fact that this isn’t really a kit–the board is fully populated and requires no soldering whatsoever. The board feels of very good quality.

All that is required is connecting the high-impedance earphone, earth/ground and aerial/antenna to the board. Since all of these components can be connected with the supplied alligator clip cables, getting it on the air took all of 20 seconds. I simply hooked up the ground and connected the aerial to my sky loop wire antenna.

I instantly heard a signal and station ID which confirmed it was our closest local broadcaster on 1010 kHz.  This station isn’t of the blowtorch variety, but is the strongest one I receive on the MW band simply due to its proximity. Audio was quite faint through the earpiece, but I believe if I tinkered with antenna length and the two variable capacitors, I could improve reception.

SWLing Post reader, Richard Langley, received his crystal radio and had a very similar experience with reception.

Credit-Card-Crystal-Radio-4

With any crystal radio (especially one this small), performance is directly correlated with antenna length, availability of a good ground connection and, of course, strong broadcasters in your vicinity.

I plan to spend an evening tinkering with this little receiver and see if I can pick up some of the night time powerhouse AM stations on the east coast.

I can say this: if you’re looking for a simple, uber-compact emergency receiver for your go-bag, bug out bag or emergency kit, this one will certainly fit the bill. This crystal receiver and all of its components weight no more than a few ounces and could easily fit in compact pouch or sleeve.

Have any other readers have enjoyed tinkering with this little emergency crystal radio?

If you would like to purchase one, try searching eBay with one of the links below. The product will only appear in the search results if currently available.

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Crystal radio credit card receiver

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CrystalReceiver

On a tip from my good friend Dave Cripe (NM0S), I just purchased this cute crystal receiver kit from a UK-based seller on eBay.

The price is 8 GPB plus 3.50 GPB for shipping. After PayPal currency conversion, I paid $17.63 US shipped from the UK–a very fair price. The kit is supplied with 5 meters of antenna wire, a high impedence earphone fitted with crocodile clips, and two double crocodile clip leads. Each unit is also tested prior to shipping. The seller also has a 100% positive rating on eBay.

I’ll certainly make a post about the radio once I receive and build it. While there aren’t as many blowtorch broadcast stations to hear these days via a crystal set, with an ample length of antenna wire, you may be surprised what you will hear. Certainly a fun and lightweight item to take camping or place in your bug out bag. No batteries required!

Update: Since making this post, it appears the item number has changed since the seller had to list a new lot of kits.  Below, I’ve made two links that search eBay based on the description, not item number:

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