No. 6 Brass Screw Cups & No. 6 Screws (1/2-inch)

A screw cup is like a washer, which the screw sits in, and it usually holds a countersunk screw, where countersinking is not possible. A number system defines the size of the screw and their cups, and most hardware stores will understand this number system. Since the little whippersnappers will not be confident to use a soldering iron, this crystal radio build uses the brass screw cup and screw connecting system as shown in the Ladybird book; Making a Transistor Radio.

For building the crystal radio, some soldering may be required including the use of a hot glue gun. This project is not a solo one, and requires collaboration between a parent or an adult and child, and the parent usually takes care of installing the screws, and soldering, if required.

Back in the old days, radio circuits required assembling on tag-boards, and this meant that manufacturers had to include long leads to their components. However, with the emergence of printed circuit boards (PCB) component leads became shorter. Therefore soldering may be required to lengthen the leads of some components. Modern non-polarised capacitors will generally tend to have shorter leads. You will also have to solder leads to the potentiometer, speaker terminals, and tuning capacitors. You could also use slide clips instead if you have those, but it might mean spending some more money.

If soldering is required then an experienced grown-up should carry it out. Do not use a soldering iron if you are under age, or do not have the experience. If you are over 18 and a hobbyist new to soldering then my Soldering Guide for Beginners, Kids, and Electronics Students will help.

In the book, they suggest using two-dozen (24) screws and cups, and that seems about the same for my build as well. However, it is always nice to have some extra, because you never know when you might need them.

The cheapest palace for No. 6 Screw Cups and No. 6 Screws is eBay, and they have some lovely shiny ones at an affordable price. Unfortunately, the cheapest seller was selling these in bags of 20 and not 24. However, it is better to get the bag of 50, that way you could also use the extra ones for other projects as well.

Brass Screw Cup System 2014

The annoying thing about the screw cup system is that you have to lift the cup washer when you want to place a wire underneath it. However, by fitting a very thin spring underneath the washer, you can see that the washer rises automatically! I am a genius! Even if I do say so myself!

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