Make: Electronics Charles Platt (smart books to read txt) 📖

as the conductors hidden inside a breadboard, so that you can retain the same layout of your components when you solder them into place. Examples are RadioShack part 276-150 (shown in Figure 3-23) for small projects and part 276-170 (in Figure 3-24) for larger projects, such as Experiment 15.

Figure 3-23. This perforated board has a pattern of copper traces similar to the pattern inside a breadboard, so that you can lay out the components with minimal risk of wiring errors, when you’re ready to create a permanently soldered version of your project.

For very small projects in which you will connect components using their wires alone, you need perfboard that isn’t etched with copper strips connecting the holes. I like the Twin Industries 7100 range (available from Mouser.com) or Vectorboard from Newark Electronics, shown in Figure 3-25. You use a saw to cut out as small a piece as you need. Cheaper options are RadioShack part 276-147 (shown in Figure 3-26), or PC-1 from All Electronics. These have little copper circles around each hole that are not necessary for our purposes, but not a problem, either.

Figure 3-24. A larger example of perforated board with breadboard geometry.

Figure 3-25. Plain perforated board (with no copper traces) can be used for mounting components when you want to do point-to-point wiring.

Figure 3-26. A small piece of perforated board with individual copper solder pads to assist you in mounting components.

Plywood

When you use a soldering iron, hot drops of solder tend to fall onto your table or workbench. The solder solidifies almost instantly, can be difficult to remove, and will leave a scar. Consider using a 2-foot square of half-inch plywood to provide disposable protection. You can buy it precut at Home Depot or Lowe’s.

Machine screws

To mount components behind a panel, you need small machine screws (or “bolts”). They look nice if they have flat heads that fit flush against the panel. I suggest stainless-steel machine screws, #4 size, in 1/2-, 5/8-, 3/4-, and 1-inch lengths, 100 of each, plus 400 washers and 400 #4 locknuts of the type that have nylon inserts, so that they won’t work loose. Check McMaster-Carr for a large and reasonably priced selection.

Project boxes

A project box is just a small box (usually plastic) with a removable lid. You mount your switches, potentiometers, and LEDs in holes that you drill through the box, and you attach your circuit on a perforated board that goes inside the box. Search All Electronics for “project box” or RadioShack for “project enclosure.”

You need a box measuring approximately 6 inches long, 3 inches wide, and 2 inches high, such as RadioShack part 270-1805. Anything similar will do. I suggest you buy a couple other sizes as well, as they will be useful in the future.

Components

Power plugs, sockets, and binding posts

After you finish a project and put it in a box, you’ll need a convenient way to supply it with power. Buy yourself a pair of insulated binding posts, such as RadioShack part 274-661, shown in Figure 3-27. Also obtain a panel-mounted power jack, size N, such as RadioShack part 274-1583, and DC power plug, size N, such as RadioShack 274-1573. The plug-and-socket pair is pictured in Figure 3-28.

Finally, you will need interconnects that are sized to fit a perforated board that is drilled at intervals of 1/10 inch. Sometimes known as “single inline sockets and headers,” but also known as “boardmount sockets and pinstrip headers,” they come in strips of 36 or more, and you can snip off as many as you need. Examples are Mill-Max part numbers 800-10-064-10-001000 and 801-93-050-10-001000, or 3M part numbers 929974-01-36-RK and 929834-01-36-RK. You can buy them from the usual electronics suppliers. Figure 3-29 shows headers before and after being snapped into small sections. Make sure that the interconnects have a terminal spacing of 0.1 inch.

Figure 3-27. These terminals, also known as binding posts, enable a solderless connection with wires that have stripped ends. Also available in black.

Figure 3-28. The socket on the right can be mounted in a project box to receive power from the plug on the left.

Figure 3-29. Single inline sockets (top) and headers (middle) allow you to make very compact plug-and-socket connections to a PC board. They can be sawn, cut, or snapped into smaller sections (bottom). The terminals are 0.1 inch apart.

Battery

After you complete Experiment 15 at the end of this section of the book, if you want to use the project on a practical basis, you’ll need a 12-volt battery. Search online for “12v battery” and you’ll find many sealed, rechargeable lead-acid batteries that are designed for alarm systems, some measuring as small as 1×2×3-inch and costing under $10. You need a charger with it, which will probably cost you about $10.

Switches and relays

You will need the same DPDT relay and the same SPDT toggle switch that were mentioned in Chapter 2 shopping list.

For Experiment 15, you’ll need magnetic switches that you can apply to doors or windows, such as the Directed model 8601, available from dozens of sources online.

Also you will need a DPDT pushbutton switch, ON-(ON) type, with solder terminals. Examples are model MPG206R04 by Tyco or model MB2061SS1W01-RO by NKK (with optional cap). Or search eBay for “DPDT pushbutton.”

Diodes

Buy at least half-a-dozen red 5 mm LEDs rated for approximately 2 volts, such as the Optek part number OVLFR3C7, Lumex part number SSL-LX5093IT, or Avago part HLMP-D155. Buy half-a-dozen similar green LEDs at the same time.

In addition, you’ll need a signal diode, type 1N4001 (any brand will do). Figure 3-30 shows an example, highly magnified. They’re cheap, and likely to be useful in the future, so buy 10 of them.

Figure 3-30. This 1N4001 diode is about 1/4 inch long and can handle up to 50 volts.

Loudspeaker

To complete the project in Experiment 15, you’ll need a loudspeaker small enough to fit inside your project box but louder than the 1-inch speaker that you used previously. It should be 2