Here are piled up tricks, tips, and know-how gleaned here and there.
Soldering Enamelled Wire
How to remove the varnish from the ends
of an enamelled wire?
Burn the length to be soldered with a match or a lighter; then immediately dip it into a 50/50 mixture of alcohol and ammonia.
Burn the length to be soldered with a match or a lighter; then immediately dip it into a 50/50 mixture of alcohol and ammonia.
Galvanic Isolation
Many radios are "AC/DC" or powered via an
autotransformer. These types are extremely dangerous for
restorers when the chassis is removed from its cabinet. The risk of electric shock
is high.
On the other hand, when connecting an oscilloscope
or an RF generator, tripping the EDF meter is guaranteed. Only one
remedy: the isolation transformer. Mine has the following structure:
It is placed in a coin box.
A Hand-Operated Coil Winder
fig.1 Eurelec Coil Winder
This hand-operated coil winder was
offered to students
of the Eurelec correspondence courses. Made of plastic, it can be reproduced
with simple means. It allowed the winding of power transformer cores,
RF tuning transformers, ...
Low-Capacitance Tube Sockets
Receiving shortwave broadcasts requires
the use of low-capacitance tube sockets. Here is a simple and
inexpensive way to make such sockets, a method indicated by
Mr. 0. Manghom from Clarens (Switzerland).
Simply wind four or five turns of 1 mm diameter bare copper wire around any 3 mm diameter rod. Then fold back the end of this wire and make a loop, as shown in figure 1. Then simply insert the spirals into the openings of the corresponding diameter ebonite panel and connect the end of the wire to a screw with a shield that will serve for connections (fig. 2). Figure 3 shows the diagram of the device with the corresponding connection screws.
Simply wind four or five turns of 1 mm diameter bare copper wire around any 3 mm diameter rod. Then fold back the end of this wire and make a loop, as shown in figure 1. Then simply insert the spirals into the openings of the corresponding diameter ebonite panel and connect the end of the wire to a screw with a shield that will serve for connections (fig. 2). Figure 3 shows the diagram of the device with the corresponding connection screws.
Making Your Own Galena
Materials
Reagents:
Procedure
- A test tube.
- A Bunsen burner or other means of heating the tube.
- Tweezers to hold the tube.
- A metal file (preferably used – files don't like soft metals).
- A precise balance.
Reagents:
- sulfur
- lead
Procedure
- Grind the sulfur into powder.
- File the lead to make fine filings.
- Mix the two powders in the following proportions:
32 grams of sulfur for 207 grams of lead. (Knowing that galena is lead sulfide PbS, therefore: 1 atom of lead for 1 atom of sulfur. The atomic mass of sulfur is 32 g/mol, that of lead 207). If the proportions are not exactly respected, there will be an excess of one or the other reagent, this is inconsequential. - Put the mixture in the test tube.
- Heat strongly.
- When the lead and sulfur have melted well, galena forms.
- Empty the contents of the test tube: among the impurities and pieces of calcined sulfur, pieces of galena (brittle and bluish body) should be found. Sometimes the tube needs to be broken.
Powering a 110V Set
Many radios were powered indifferently by 110V DC or 110V RMS.
Today, the voltage offered by EDF is AC, sinusoidal, vibrating at 50Hz and with an
RMS value of 230V (it can drop to 220V at the end of the distribution line).
There are two methods to reduce the voltage at the terminals of the radios: the transformer
and the dropping resistor. The transformer or autotransformer solution will be
preferred because it causes very few losses (10%) compared to 50% for the dropping
resistor. In the USA, for a few euros plus shipping, transformers for
travelers to Europe can be found. The distribution in North America is 110V/60Hz.
The traditional heating cord is a simple resistor with a value equal to
$$R_2=\frac {120}{I_A}$$
where IA is the RMS current, in Amperes (A), consumed by the radio.
This resistance can be split into 2 resistors of ½ R2 distributed across the mains terminals. These solutions have the serious disadvantage of energy loss equal to that consumed by the set.
This can be reduced by a factor of 2.2 by inserting a rectifier diode and decreasing $R_2$ by a factor close to 2.22.
$$R_1=\frac {120}{2,2.I_A}$$
This resistance can be split into 2 resistors of ½ R2 distributed across the mains terminals. These solutions have the serious disadvantage of energy loss equal to that consumed by the set.
This can be reduced by a factor of 2.2 by inserting a rectifier diode and decreasing $R_2$ by a factor close to 2.22.
$$R_1=\frac {120}{2,2.I_A}$$
Whitening Yellowed Plastic with RetroBright
Read this complete article by Dave Stevenson from Manchester, UK, aka 'Merlin'. A summary here:
RetroBright Preparation
Operating Procedure
RetroBright Preparation
- Hydrogen peroxide 130 volume (DIY stores). This is the active ingredient. Dangerous product! Wear gloves and goggles
- Vanish OxiAction Crystal White (supermarket). This is the catalyst. 2 pinches per 100ml of peroxide.
- Gallia Gumilk (pharmacy). Thickener causing gel formation. 1 teaspoon per 100ml of peroxide.
- UV lamp. It provides the energy for the reaction. Available in pet stores (10 UVB).
Operating Procedure
- Before applying the RetroBright gel, clean the part to be treated with soap, rinse and dry.
- Spread the gel with a brush on the elements to be whitened.
- Place under the UV lamp. Monitor the progress of whitening and reapply product which will tend to foam and liquefy.
- After a time ranging from 48 to 72 hours. Rinse, dry. It's finished!
Some links
Hydrogen peroxide is a dangerous product. Perform these operations outdoors or in a well-ventilated area.
