The following images show what bad and good solder joints should look like.
These joints may have been too cold and the leads trimmed so closely that the solder was cut through and the connections broken. It appears that no soldering flux was used.
The solder is shiny and the leads are trimmed just above the cone of solder. The leads of the terminal block at the bottom have not been trimmed.
One way to judge the height at which to cut a components leads is to place a piece of wire or a section of previous cut lead that is the same diameter as the lead to be cut flat on the surface of the circuit board. The cutters are then lowered to rest on the wire and the the cut is made.
I usually do not solder the pads of unused terminals of integrated circuits.
The explanations for the circuits on these pages cannot hope to cover every situation on every layout. For this reason be prepared to do some experimenting to get the results you want. This is especially true of circuits such as the "Across Track Infrared Detection" circuits and any other circuit that relies on other than direct electronic inputs, such as switches.
If you use any of these circuit ideas, ask your parts supplier for a copy of the manufacturers data sheets for any components that you have not used before. These sheets contain a wealth of data and circuit design information that no electronic or print article could approach and will save time and perhaps damage to the components themselves. These data sheets can often be found on the web site of the device manufacturers.
Although the circuits are functional the pages are not meant to be full descriptions of each circuit but rather as guides for adapting them for use by others. If you have any questions or comments please send them to the email address on the Circuit Index page.