Electronic Design Software

How can I troubleshoot electronic soldering projects that do not work properly?

I have my students build a blinky robot with resisitors, transistors, capacitors and LEDs in my electronics class. After they build the project, sometimes they dont work properly. I wish i knew how to use a multimeter to troubleshoot their projects and identify which parts are damaged or defective. Any ideas?

Public Comments

1. For a start you can compare resistances with no power applied with a good ( working) circuit. Use the diode checker function also and try both polarities. If a section does not match what it should then measure the parts of that section and compare with the good circuit should isolate the mistake, such as incorrect resistor or backwards LED. For capacitors, just a visual examination of the correct values and polarities should be sufficient.
2. Troubleshooting student electronic projects, always fun! The multimeter is the most basic electronic test instrument. Get one and practice using it. As you may already know, the DVM measures voltage, current, resistance, and sometimes other electronic parameters. There is nothing to using one of these devices. Just don't try to measure resistor values with the voltage applied to the circuit under test. Otherwise, the DVM is pretty much fool-proof for all other measurements. You don't say if the projects are all the same type using the same diagram and components. If so, that should make things a little easier. First place to start is to find one project that works properly, use it as the model. Take your DVM, digital volt meter,(circuit power turned off) and measure all resistor values for all resistor configurations in the circuit. Do the same for all voltages at key points such as transistor collector/base/emitter leads, diode anode votage, and voltages across key capacitors and resistors networks. Record these measured values directly on the circuit diagram, if available. From this, you can make comparisons when troubleshooting defective circuits.