The super probe is a simple and cheap to manufacture device with a wide range of functions and capabilities, built on a single PIC16F870 microcontroller from Microchip. A four-digit seven-segment indicator is used to display operating modes, parameters, and functions.

Operating modes: logic probe, pulse generator, frequency meter, pulse counter, voltmeter, p-n junction voltage (diodes, transistors), capacitor capacitance meter, inductance meter, 500 Hz signal generator, NTSC video signal generator, ASCII table generator (RS-232) , MIDI note generator, pulse generator for servo controllers, square wave generator, pseudo-random number series generator, pulse generator for testing IR receiving modules, PWM.

The schematic diagram of the device is shown in the figure below.

The four-digit LED used is LTC4627 (or MSQ4911C) with a common anode. Low drop out voltage regulator – LM2931. The regulator remains operational in the input voltage range of 5.0…30.0 V and has a power supply reverse polarity protection circuit.
As you noticed, the circuit design is very simple; there are no ordinary resistors in the indicator circuits. They are usually used for each indicator segment (connected in series with the segment) to limit the current and to ensure that the segments illuminate equally. The PIC microcontroller limits the current to approximately 25 mA per line, and the software is designed so that only one segment is active at a time. This method also eliminates the effect of multiple segments. Despite its simplicity, the device does not require any adjustment and has good repeatability: numerous manufactured versions have shown reliable and decent performance.

In different operating modes, resistors R1 – R6, R10 are used, but differently for each mode. Unused resistors for specific modes are disconnected from the circuit by driving the corresponding I/O lines of the microcontroller. Resistor R5, for example, is used in pulse generator mode, R4 is used to charge the capacitor when measuring its capacitance.
The device is assembled on a circuit board, which is mounted in a suitable housing

The selection of operating modes is carried out by the BUT1 button while holding down the BUT2 button. Changing operating modes occurs cyclically, the name of the mode is displayed on the indicator. Exiting any mode is done by pressing and holding two buttons. The selected operating mode is saved when the power is turned off, which is convenient when powering the probe from the circuit under test.
Information about operating modes, description and operating procedure.

This probe can be used to quickly determine the capacitance of capacitors in PF, NF, check their stability under temperature changes, find broken wires, trace wires on printed circuit boards, and also to search for live wires without touching them. The circuit uses only three transistors and a couple of other radio components. Simplicity allows you to assemble it in just an hour.

Probe circuit for an electrician

List of detector components

• C1 trimmer capacitor 30pf
• C2 1nF
• D1 1N4148
• LED1 3mm
• Q1 BC559C
• Q2 BC559C
• Q3 BC549C
• R1 1M
• R2 2M
• R3 5M
• R4 2m
• R5 1M5
• R6 33k
• R7 33k
• R8 270R
• SG1 piezoelectric speaker

When the capacitor being tested touches the sensor, the circuit beeps at a frequency that varies depending on the capacitance. If the user has sufficiently damp skin, simply holding one terminal of the capacitor while testing while touching the other to the probe is all that is needed to trigger the sound.

When the probe is properly configured it consumes only 10 µA - that is, a power switch is required. The design is optimized for capacitors smaller than 0.1 µF. Large capacitors produce too low frequencies. The entire device is powered by two CR2032 lithium cells that fit into a TicTac box. Using a power switch is unnecessary as the circuit consumes almost no power when not in use.

This electrician's probe will become your indispensable assistant and has many uses, such as:

1. Quickly check the capacitors.
2. It is easy to detect small deviations in TKE capacitance as the capacitor heats up or cools down.
3. Cable Finder - At various points on a live cable, the sound changes during listening due to changes in capacitance.
4. Determine the performance of varactor diodes. They squeak at a much lower pitch than normal ones.
5. And if you make small flat electrode plates, then the voltage of the wiring lines can be detected due to the electric field. Follow wiring in walls and ceilings and locate them without touching them. The signal is modulated by AC voltage, causing a vibrating sound at 100 Hz.

The probe itself is made of 1 mm wire. The second contact from the ground is formed using a screw. Capacitor C1 regulates the capacitance to set the LED glow and the sound of the piezo speaker.

Since you have decided to become a self-taught electrician, then probably after a short period of time you will want to make some useful electrical appliance for your home, car or cottage with your own hands. At the same time, homemade products can be useful not only in everyday life, but also made for sale, for example. In fact, the process of assembling simple devices at home is not difficult at all. You just need to be able to read diagrams and use the ham radio tool.

As for the first point, before you start making electronic homemade products with your own hands, you need to learn how to read electrical circuits. In this case, ours will be a good helper.

Among the tools for novice electricians, you will need a soldering iron, a set of screwdrivers, pliers and a multimeter. To assemble some popular electrical appliances, you may even need a welding machine, but this is a rare case. By the way, in this section of the site we even described the same welding machine.

Special attention should be paid to available materials, from which every novice electrician can make basic electronic homemade products with their own hands. Most often, old domestic parts are used in the manufacture of simple and useful electrical appliances: transformers, amplifiers, wires, etc. In most cases, novice radio amateurs and electricians just need to look for all the necessary tools in a garage or shed in the country.

When everything is ready - the tools have been collected, spare parts have been found and minimal knowledge has been obtained, you can proceed to assembling amateur electronic homemade products at home. This is where our small guide will help you. Each instruction provided includes not only a detailed description of each stage of creating electrical appliances, but is also accompanied by photo examples, diagrams, as well as video lessons that clearly show the entire manufacturing process. If you do not understand some point, you can clarify it under the entry in the comments. Our specialists will try to advise you in a timely manner!

The indicator is a device that is used to search for zero and phase. Light indicators are in demand because they are reliable and low cost.

The indicator consists of a dielectric housing. Inside it is a neon light bulb and a resistor. If the light comes on when touched, it means it is in phase. If not, it's a neutral wire.

Externally, the indicators are different, but the principle of operation is the same. To avoid a short circuit, place a piece of insulating material on the screwdriver. Do not tighten the screws with the indicator screwdriver, since the rod is pressed into the housing. With great force, the plastic may burst.

LED indicator – probe for searching for phase and zero

Such an indicator allows you not only to look for phase and zero, but also to ring the circuit, check the functionality of heating elements of devices, light bulbs, and network wires. There are models that have the function of searching for wires in the wall without drilling or damaging it.

Structurally, this probe is no different from the previous one. With the difference that it has an active element (microcircuit or transistor) instead of a neon lamp, small batteries and an LED. The call is made in the same sequence. Just don’t touch the metal pad on the device! It is designed to check the integrity of electrical circuits. If you touch this pad when checking zero, the LED will light up and it will seem to you that this is a phase wire.

According to standards, the phase wire should be located on the right side of the socket.

How to make a probe indicator yourself to find phase and zero on a neon light bulb

To make such a device, just solder a resistor to any terminal of a neon light bulb. The resistor should be insulated with a tube.

The body can be made from a screwdriver or a ballpoint pen. This sample will not differ from the purchased one. The phase search is done in the same way.

Electrician's check on a light bulb

A tester is a low-power light bulb screwed into an electric socket, used to check the presence of voltage in the network. 2 conductors (stranded wire) 50 cm long are connected to the cartridge.

To check, you need to insert the wires into the socket. If the lamp is on, there is voltage.

Electrician's control on LED

The control on the light bulb requires attention, as it may break. Therefore, it is better to use an LED control. It is small in size. Below is a diagram of such a device

The LED can be used in any type and color. It is connected in series with a current-limiting resistance. It's just as easy to use.

The LED can be placed towards the handle. The photo shows a car control.

Phase search in the presence of neutral and ground conductors

If there is a need to find the phase of wiring that has neutral, phase and ground wires, this can be done by testing. Assign numbers to each wire (conditionally). For example, 1, 2, 3. Touch the wires in pairs 1-2, 2-3, 3-1.

Changes need to be recorded by a light bulb:

• Touching 1-2, the lamp does not light. Wire 3 phase
• Touching 2-3 and 3-1, 3 phase wire.

Why? When connecting the wire to ground or neutral, the light will not light up, because these conductors on the shield are connected together. Instead of monitoring, you can use a voltmeter, choosing to measure alternating current and rated up to 300 V.

Finding phase and zero using potatoes

If you do not have special equipment, then you can find the phase with potatoes. One end of the conductor should be connected to a battery or metal pipe. If the pipe is painted, strip it down to bare metal.

Insert the opposite end of the conductor into the cut of the potato. Another conductor is also stuck into the potato through the maximum distance. The second end should be brought through a resistor (at least 1MΩ) to the electrical wiring wires and touch them one by one. Wait. If there are changes in the cut of the potato, this is a phase. If no changes are observed, it is zero. You should not use this method if you do not know the safety rules when working with electrical installations.

In noisy workshops it is not entirely convenient to use testers with sound indication. When poking at the machine diagram, you have to simultaneously hold the probes of the device and look at its readings, click the tester operating mode switch. Electricians in simple circuits where measurement accuracy is not needed usually look for such faults as: a short circuit or open circuit, whether the magnetic starter coil is intact or broken, whether live parts are energized. This probe allows you to check the presence of a phase in the network, a short circuit and the presence of resistance in the circuit. Using it, you can check the coils of magnetic starters and relays for open circuits, ring the ends of chokes and motors, deal with the terminals of multi-winding transformers, check rectifier diodes and much more. The probe does not have a power switch or operating mode switch. It is equipped with two red and yellow LEDs, as well as a neon lamp. The probe is powered by a 9 V Krona battery; the current consumption when the probes are closed is no more than 110 mA; when the probes are open, it does not consume energy. The functionality of the device is maintained when the supply voltage is reduced to 4 V. When the battery is discharged below 4 V, the probe works as an indicator of the mains voltage.

When the circuit resistance is tested from zero to 150 ohms, the red and yellow LEDs light up; when the circuit resistance is from 150 ohms to 50 kOhms, only the yellow LED lights up. When a mains voltage of 220-380 V is applied to the probes, the neon lamp lights up and the LEDs flicker slightly.

Circuit operation

The probe is made of three transistors. In the initial state, all transistors are closed since the probe probes are open. When the probes are closed, a voltage of positive polarity is supplied through diode VD1 and resistor R5 to the gate of field-effect transistor V1, which opens and is connected through the base-emitter junction of transistor V3 to the negative wire of the power source. LED VD2 flashes. Transistor V3 also opens, LED VD4 lights up. When connected to resistance probes within the range of 150 Ohm-50 kOhm, the VD2 LED goes out, since it is shunted by resistor R2, the resistance of which is relatively less than that measured, and the voltage on it is not enough for it to glow. When mains voltage is applied to the probes, the neon lamp HL1 flashes. A half-wave mains voltage rectifier is assembled using diode VD1. When the voltage on the zener diode VD3 reaches 12 volts, transistor V2 opens and thereby locks field-effect transistor V1. LEDs flicker slightly.

About details

We will replace the field-effect transistor TSF5N60M with 2SK1365, 2SK1338 from pulse chargers of a video camera, etc. Transistors V2, V3 are replaceable with EN13003A from an energy-saving lamp. Zener diode D814D, KS515A or similar with a stabilization voltage of 12-18 V. Small-sized resistors 0.125 W. Neon lamp from a screwdriver indicator. AL307 LEDs or other similar ones, red and yellow. Any rectifier diode with a current of at least 0.3A and a reverse voltage of more than 600 V, for example: IN5399, KD281N.

When installed correctly, the probe begins to work immediately after power is applied. During setup, the range of 0-150 Ohms can be shifted in one direction or another by selecting resistor R2. The upper limit of the range 150 Ohm-50 kOhm depends on the instance of transistor V3.

The probe is placed in a suitable housing made of insulating material. I used the case from a phone charger. A probe-pin is brought out from the front onto which a piece of PVC tube is placed, and from the opposite part of the body there is a wire made of good insulation with a pin or crocodile.

REMEMBER that when working with this probe you must FOLLOW ELECTRICAL SAFETY RULES!

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