- Estimated Time
- 30 minutes
- Skills Required
- Basic Soldering
- Parts Required
- (1) Pack Resistor kit- Radio Shack Catalog # 271-312
(1) PC Board- Radio Shack Catalog #276-148
(1) Pack PC Board Terminals- Radio Shack Catalog #276-1388
- Tools Required
- Soldering Iron
The purpose of this tutorial is to demonstrate a simple and clean method of basic circuit construction by using desoldering braid to make the traces on the board.
The example circuit constructed will be from the tutorial on how to use a voltage divider to measure the voltage of a battery. This circuit is for example only and we will be concentrating on the techniques rather than the circuit itself. For a schematic and detailed explanation of the circuit operation see this tutorial:
A word of caution: This technique should not be used when it is possible for something conductive to touch the back of the circuit board. This could cause the traces to short and damage the components on the board.
Building the board
Gather all of the parts for the example board and heat up the soldering iron. Figure 1 shows the required parts.
Place the components in the board as shown in the next picture. Take care to gently spread the leads of the resistors once they are inserted but do not clip the leads off yet. Note that the resistors are off to one side of the board. This is to allow room for electronic filtering to be added later if needed.
Flip the board over and bend the middle resistor leads so that they cross each other. Apply a small amount of solder to these leads and clip them off as shown in figure 3. Do not dispose of the clipped leads. They will be useful to connect alligator clips to the screw terminals once the circuit is complete.
Pull a few inches of the desoldering braid out of the roll. Tin the braid by applying heat with the iron on one side of the braid and solder on the other. The braid should be bright silver and thoroughly covered with solder. See Figure 4.
Apply a small amount of solder to the vias about half way between the points that need to be connected according to the schematic. This will help the braid lay flat against the board. Do the same thing at any point where the braid needs to turn a corner in the board layout.
Apply heat to the solder joint with the iron and slide the tinned braid into the joint so that it lies flat on the board and makes contact with the pin. See figure 7.
Lay the braid flat against the board and apply heat with the iron at the next joint, making sure that the braid contacts the lead to be soldered. If the braid sticks up a bit then it can be gently pushed into place with a hot iron tip.
Cut the braid off at the top of the solder joint. If the braid is not cut completely flush then it can be shaped as needed with a hot iron. Reheat the same joint and apply the next piece of braid as before. Once again, make sure that the braid is flat against the board and touching the lead.
Lay the braid across the board until it contacts the previously tinned via. Heat the braid over the top of the via so that the braid is soldered to it. See figure 9
Continue laying the braid across the board to the next joint and connect it to the next lead. Cut the braid at the top of the joint. Lay the next piece just like all of the others.
This trace will turn a 90 degree corner. Start running the braid just as before and secure it to the pre-tinned via where the braid will turn the corner. See figure 11.
Cut the braid just past the via. Run a very short piece of braid between the pin and the end of the last piece of braid. Be very careful as this piece will not be long enough to wick away much of the heat as the small piece may not stick correctly or the via may be damaged. Secure the braid against the last piece and cut it flush. See figure 12.
Done! While this was a pretty simple circuit, this construction demonstrates a few techniques that are easily transferable to larger circuits. If you are careful with the initial parts layout, then this method of circuit construction can be extremely quick and easy.