Hanging Garden
If we'd like to get away without the bulky, wooden board, we can dispense with the board altogether and just lay the parts out on a flat surface and solder them where the cross, maybe twisting the leads together at joints for reliability. The circuit can usually be laid out to closely follow the schematic diagram in many cases if no integrated circuits are involved, and so it's fairly easy to see how to debug. The down side is that without some means of supporting the lattice of parts, the whole circuit is mechanically fragile and almost certain to fail with the slightest bending or twisting. To avoid this, the whole circuit can be laid on a bit of cardboard, plastic, etc. and some casting resin poured over it. When the resin hardens, the circuit is going to still be functional, and now the resin will prevent most bending, twisting and shorts.
The Hanging Garden Style will accommodate IC's to the extent that you are careful about wiring to the IC leads. It helps if you bend every other lead on the IC (or socket!) out at right angles to the orientation of the other pins just to give yourself some room to work.
Dead Bug
Which leads us to dead bug building. This is a variation of the Hanging Garden that gives a nod to reliability. The parts are first glued, leads up, into place on some substrate, like a bit of phenolic board or even Plexiglas. The leads are then formed to make the joints, soldered, and trimmed. When the circuit is tested and proven to do the proper task, the whole thing can have reliability poured over it in the form of casting resin just like the Hanging Garden. Note that the resin can be a minimal layer just to bond the parts permanently to the substrate if you have a solid substrate like phenolic, Plexiglas, countertop laminate, glass-epoxy board, or something similar. It can also be poured in a thick layer if the substrate is something that will not supply much support, like cardboard. You can cover the whole mess up entirely if you like solid-block circuits.
Dead Bug can accommodate IC's fairly easily.
The Dead Bug technique is also useful for partial circuits, notably when you have an IC that has a different pinout than a printed circuit board was designed for. You glue the IC's top surface to the PCB, legs up (hence the name, "dead bug") and then run small wires to the holes to rescramble the pinout to what the board expects.
Dots and Dashes
One step more modern than the true wood-and-nails breadboard is "Dot and Dashes". This is a trick used by some amateur radio experimenters. For Dots, you cut or punch a number of small bits of printed circuit stock, perhaps 0.2" (5mm) across, out of a bard board of double sided copperclad. There are cheap (US$20.00) hole punch sets at some tools suppliers that makes this easy. If you have access to a shear, this can also shear up rectangular bits of copperclad board (Dashes!) easily. With your dots, you glue or solder the dots down to another board (glue for non-copper clad substrate, solder for copperclad). The dots form solderable, insulated islands of copper over the substrate. Using a copperclad substrate allows the whole copper substrate to be grounded, which is very good for RF building, and usually OK for audio.
Dots and Dashes are too large to easily accept IC leads, as the size of a usable DOT is just too big for the 0.1"/2.5mm spacing of most IC leads. A hybrid version is possible, setting the IC's down in Dead Bug Style and using Dots for everything else. |
