For car enthusiasts who perform repair work on their own, there are combined measuring devices specially designed for making control measurements on cars. With the help of such a device, it is possible to measure engine speed, the angle of the closed state of the ignition system breaker contacts, as well as voltage up to 20 V. Such a device, as a rule, can measure resistance in the range of up to one kilo-ohm, i.e. from 1 to 1000 Ohm.
In addition, devices for testing electrical and electronic components are offered. They allow measuring both small resistances of several Ohms and large ones, in the megaohm (mOhm) range. With these devices, it is possible to measure voltages (in volts) with very high accuracy, which is especially necessary when testing electronic units.
If you just need to make sure whether there is any voltage in the circuit at all, then a regular tester with a control diode lamp will do. This, of course, only applies to circuits that do not contain electronic components, since electronic devices are extremely sensitive to too high currents. Sometimes electronic components are damaged already at the moment of connecting such a control lamp.
Attention! To check voltages in circuits containing electronic components (transistors, diodes, relays) a high-impedance voltage tester is needed. It performs almost the same task as a test lamp, but does not damage electronic circuits and is suitable for performing any tests.
[Original published on the portal www.PeugeotBook.ru]