The Mystery Crystal
my version of the famous Mystery Crystal Set from Australia. Click
Here for a complete set of plans
and a brief history of the set.
view showing the nice vintage Apex dial I used. The
plastic material is half-inch thick DuPont Delrin®.
which looks like the old
hard rubber that was
used in the 1920's and 30's. It is very hard and machines easily
can see by the
fancy cut over the dial. This was the first time I used this, and
was very pleased with the results. The binding posts are
NOS 1920's style.
The three on the left are for the various combinations of antenna and
The two on the right are for the headphones.
side view. I
used solid mahogany for the base to which I applied 6 coats of clear
gloss lacquer, sanding between each coat. There is no stain on
the wood, what you see is the
natural color. The wiring is
all # 14 square
buss wire I obtained from Antique
Electronic Supply several years ago.
Unfortunately, they were not suppling this size when I checked
last. If you find a new source for this wire, please let me
know. The variable
capacitor is an AMSCO straight line frequency unit.
Notice the shape of the plates. This makes the tuning spread more
evenly across the dial. A very well made part. For the coil construction, I used a piece
of three-inch diameter
phenolic tubing. The wire is NOS authentic green silk-covered
from my collection. I really hate to use any of this wire because
it is irreplaceable. Again, if anyone knows a source for this
kind of wire, please, please let me know. I usually apply a coat
or two of polystyrene when I finish a winding, but I didn't coat this
coil because I didn't want to risk changing the look of it. It
seems to be very stable the way it is.
side view. Here, you can see one of my homebrew crystal
detectors. The bypass capacitor is also homebrew with a scanned
copy of an
original capacitor label.
view of the AMSCO capacitor with the unusual plates. If you look
closely at the coil, you can see the second winding in between the
closeup of the detector. This is a CARCO style from the
1920's. Here again, I used Delrin®
base with vintage terminals and all other parts made of brass which I
nickel plated. I really like the CARCO catswhisker construction,
it is easy to adjust and stays where you leave it. The crystal is
a standard Galena mounted in low temp alloy.
Click here to
return to the VINTAGE HOMEBREW page
I am using a set of 3000 ohm Pennsylvania brand headphones. These
work fairly well. I have had best results with a matching
transformer and sound-powered phones. This set is very selective
and you can get more volume on local
stations by changing the input connections.
© 2006 ~ 2008 Michael R. Starcher ~
All Rights Reserved