Power regulator on the triac BTA16-600

Power regulator for various loads, such as incandescent lamps, heating elements, etc. It is possible to regulate the speed of the electric motor, but is the power lost?

The thyristor is designed for a current of up to 16 Amperes, it is without a snubber and therefore in the diagram R3-C2 perform the function of a snubber

 

Longwave radio transmitter on one transistor 2SK30A

Long wave radio transmitter at a frequency of approximately 170 kHz with a range of no more than 10 meters with a ferrite antenna. Transistor 2SK30A. Winding L1 contains 60 turns and winding L2 contains 20 turns, wire with a diameter of 0.14 mm. Ferrite core with a diameter of 8-10 mm and a length of 8 centimeters, but these data on ferrite can be changed, this will only change the frequency.

When you turn it on for the first time, the transmitter should start working immediately, otherwise swap the terminals of the L2 coil or wind and unwind the turns of the wire.

 

How to assemble and configure SSB power amplifier 3.5-30 MHz

Today you can buy on the Internet a rather popular kit for assembling a homemade power amplifier for a radio station or a homemade radio transmitter, which operates at frequencies from 3.5 to 30 MHz (SSB + CW, with amplitude modulation I have not tested) and has a maximum output power of 70 W, but such power will not be in the entire frequency range. With this amplifier I conducted radio communication at a distance of 3100 kilometers at a frequency of 7 MHz. I will show you how to assemble and configure this amplifier.

This kit does not have a radiator to remove heat from the transistors, you need to find it yourself. Also required is a power source up to 14 volts and a current of 6-8 amperes. Transistors used IRF530N two pieces. First, you need to wind two high-frequency transformers: input and output.

You need to break off four plates from the board. The input transformer is wound on a ferrite core, similar to a pair of binoculars. Insert two metal tubes into the ferrite and solder the plates to their ends. These two tubes are just the secondary winding with a tap from the middle. Wind two turns of insulated wire through these tubes - this will be the primary winding of the transformer. Solder the finished transformer to the board.

The output transformer is assembled from two ferrite tubes, into which two metal tubes are inserted, to the ends of which two plates are soldered. Everything is exactly the same as in the input transformer. Three turns of insulated wire must be inserted and wound into these tubes.

You can wind the wire after you solder the transformers to the board

Next, we solder the electronic components onto the board; the relay contacts need to be bent

The power choke contains two turns of wire in varnished insulation. Since such a wire is inconvenient to wind, I wound two turns of wire in insulation that I found on my own.Jumpers JP1 and PTT should be plugged. If you have an output filter, then jumper JP1 should not be plugged. You can connect the filter to the LPF in-out contacts.

Here is the aluminum radiator I found. I drilled holes for the transistor flanges. The transistors need to be isolated from the radiator, for this purpose the kit includes thermal pads and plastic bushings into which you need to insert screws and secure the transistors. These plastic bushings are very important and you need to be careful and check whether the transistor drains are isolated from the radiator.

Here is the amplifier assembled

I soldered two pieces of coaxial cable with a wave resistance of 50 Ohm to the input and output of the amplifier. I have not soldered special SMA connectors yet.

Now we set up the amplifier. We supply 13 volts. Just in case, connect a load to the amplifier output - a 50 Ohm resistor. No signal is supplied to the amplifier input. The trimmer resistor must be set and adjusted to a voltage of 3.5 volts on the gate-source of two transistors, the current consumption will be about 70 mA. When switching on for the first time, it is advisable to set the rotor of the trimmer resistor to a position in which the lowest voltage will be supplied to the transistor gates.

This is my 50 ohm resistor rated for 40 watts. It consists of 20 1k ohm resistors in parallel, each dissipating 2 watts. This resistor has the lowest inductance, wirewound resistors are not suitable.

After the voltage on the transistor gates has been set, you can now check the operation of the amplifier. I have a homemade radio transmitter with a power of 200 mW at a frequency of 27 MHz. I connected the output of this radio transmitter to the input of the amplifier, and connected a device measuring power to the output of the amplifier. As you can see, the output of the amplifier will be 7000 mW or 7 W of output power with an input of 200 mW.

Next, I connected the transceiver output to the amplifier input. I received my La-La-La signal at a distance of 3100 kilometers in the city of Oslo, Norway.

Field effect transistor 2n7002.60V 120mA (smd 702)

2n7002 (SMD702) is an n-ch field effect transistor  that can be found on old computer motherboards

drain-source voltage - 60V

drain current-120mA (pulsed 800mA)

gate-source voltage-20V

 power dissipation 200mW (25C)

gate threshold voltage 1-2.5V

Rds 1.2-7.5 Ohm (10v 500mA)

 

DIY Interturn short circuit tester for anchor or stator of electric motors

With this simple tester, you can find an interturn short circuit in the anchor or stator of an electric motor, even if one turn in the windings is shorted.

A transmitter is assembled on the VT1 transistor, a receiver on VT2, a detector on the diode, and a signaling device on VT3-5. Coils L1-L2 are in the same plane at a distance of 3 cm from each other and are well fixed. If you bring the anchor with a closed turn to these coils from the side, the LEDs will switch and show in which groove the coil with a closed turn is wound.

Coils L1-L2 are wound on ferrite dumbbells 10 mm long with an unknown ferrite. You can wind the coils on the dumbbells that you have, the magnetic permeability of the ferrite can be different. I took ready-made chokes. Choke L1 with an inductance of about 990 μH, L2 - 9.8 mH, a difference of ten times. This inductance can be different, there is no clear data on these coils here. The transmitter coil must emit a signal of sufficient strength, and the receiver coil must also receive it with sufficient strength. A diode of the 1n4148 type can be used, etc., but the voltage drop on silicon will be greater. It is advisable to use transistors VT2 and VT3 with a high gain.The device can be tested, adjusted and configured in a cascade by surface mounting. First, you need to assemble a signaling device on transistors VT3-5 and a diode. The anode of the diode is not connected anywhere. When power is supplied, the LED on the right according to the diagram lights up. Touch the anode of the diode and the power plus with your finger, the LEDs will switch, the transistor VT5 will be open by the closed transistor VT4.

The transmitter on VT1 can be checked with a long-wave radio receiver; by bringing the receiver to the L1 coil, the hissing will be quieter. This is a generator of a sinusoidal signal with a frequency of approximately 30-35 kHz and a peak-to-peak amplitude of about 8 volts.

The device is adjusted by the trimmer resistor R4. The operating mode can be set in different ways. If you check closed turns without a core, then you need to make sure that the LED on the right side of the diagram initially lights up. Bring one closed turn to the coils L1-L2, the device will respond by switching the LEDs. If you check closed turns with a magnetic circuit, that is, an anchor or stator, you need to set the LED glow on the left side of the diagram with a resistor, and the LED on the right side should not light up

Now, slowly rotating the anchor near the coils, you can find the short circuit of the turns in the anchor. When the turn is closed, the LED on the right will go out, and the left one will light up. In this case, you can determine in which slot the winding with the closed turn passes. Since the winding passes through two slots, the LED on the left will light up twice.