The probe lamp is a feature of great utility for the bench, serving to search for defects in electrical appliances and electronics that are fed by the power grid, in addition to components
Such as fuses, motors, lamps, solenoids, reactors, transformers, etc.
The probe lamp verifies the continuity of the devices or devices in evidence and still prevents "bursts" from occurring when they are short, when they are connected directly to the power supply, without any protection.
The series lamp or probe lamp we describe is more sophisticated because it uses not only a common bulb and two probes like the simple versions.
Our version has two test lamps under test conditions with different wattages and there is also a diode that allows continuous pulsed current tests on polarized components such as diodes and high voltage capacitors.
The circuit can be powered by both the 110 V and 220 V mains depending on the lamps used.
As it is a device that will be connected directly to the power grid, the assembler must take utmost care with the handling of the components and the assembly, isolating living points and much more taking care of, avoiding touching in places that can cause shocks.
In figure 1 we have the complete diagram of the series lamp.
In figure 2 we have the layout of the components of the assembly that do not require a printed circuit board.
We suggest that all the elements be fixed in a wooden or plastic box.
For lamps, which should be ordinary incandescent lamps, we use sockets. X1 is a common 5 to 20 watt light bulb while X2 should be 40 to 60 watts with voltage according to the local power grid.
S1 and S2 are simple switches. Diode D1 must be of type 1N4004 if the network is 110 V and 1N4007 if the network is 220 V.
In normal use as a standard lamp, we keep S1 closed and, if we are going to prove low consumption devices such as small transformers and solenoids, we let S2 open.
If the smaller lamp comes on at maximum brightness in this test, we close S2 and if X2 also lights up at maximum intensity, it is a sign that the device under test may be shorted.
If the brightness is reduced or below normal, the appliance is in good condition in terms of consumption (there is no shortage). If the lamp does not light (X1 or X2 off) in the indicated tests we will have a device open.
For pulsed direct current testing, simply open switch S1.
This test applies, for example, to high voltage electrolytic capacitors that must be charged. The lamp should give a "slight blink" and then remain off. If it remains lit, the capacitor is shorted.
Note that PP1 is the positive probe and PP2 is the negative probe.
High voltage rectifier diodes such as 1N4004 or 1N4007 can be tested with open S1.
MATERIAL LIST
D1 - 1N4004 (110 V) or 1N4007 (220 V) - silicon diode
S1, S2 - Single switches
PP1, PP2 - Probes - red and black
X1 - 5 to 20 W - common lamp
X2 - 40 to 60 W - common lamp
Miscellaneous:
Power cable, sockets with fixing screws for lamps, mounting box, wires, solder, etc.
