Reliable lab power supply

I have an adjustable power supply. Only the voltage is regulated, respectively, there is no current adjustment. For some purposes it is enough. I decided to assemble a unit with adjustable current and voltage. The laboratory power supply, then the LBP, is a very necessary thing. The LBP circuit is very simple, because I will use it.

Specifications

The main characteristics of the module:
  • Input voltage 5 - 40 Volts;
  • Output voltage 1.2 - 35 Volts;
  • Output current (max) 9 Amps, it is advisable to install a cooler.

Power Supply Scheme

As already mentioned, the circuit is simple. The mains voltage is supplied to the transformer. There is a mains switch and fuse. Voltage is lowered by a transformer. Upper honor circuit power. AC voltage is supplied to the diode bridge and the smoothing capacitor. Next comes the DC-DC converter. From the converter, the voltage goes to the output terminals. The minus of the circuit is broken by the device.For convenience, adjusting resistors are removed from the board. The lower one is designed to power the volt-ammeter. The transformer has a separate winding. As with the power winding, the AC voltage is supplied to the diode bridge and the filter capacitor. Next, set the linear stabilizer to 5 Volts.
Reliable laboratory power supply

Components

With the scheme sorted out. Now go to the components. The LBP case will be the old case from the regulator of the soldering iron. The regulator of the soldering iron is still the time of the USSR. Very solid.
Reliable laboratory power supply
The front panel will be made of composite plastic. Plastic consists of two plates of aluminum and plastic in between. On the one hand, it is white, with the second black. The black side will be the front.
Reliable laboratory power supply
Step-down transformer from old equipment, I do not remember which one. It had to be slightly modified. Made a tap on 22 volts, full winding on 27 volts. If you leave, then after the diode bridge voltage of more than 30 volts.This is a lot for the stabilizer 7805 installed on [leech = http: //] DC-DC converter [/ leech]. It feeds the operational amplifier of the circuit. Although 40 volts is stated, considering the maximum for 7805 is 30 volts.
Reliable laboratory power supply
.
Reliable laboratory power supply
. To more accurately display the output parameters, you need to apply to the 4th segment. I used it as I did.
Reliable laboratory power unit
Terminals of the times of the USSR. Strong and reliable.
Reliable laboratory power supply
4700 microfarads capacitor * 63 Volts. Based on 1000 microfarads per 1 Ampere. The module has 2 * 470 microfarads installed.
Reliable laboratory power supply
The diode bridge can be taken as one, but I have remained from the old project. Assembled on 4 D242 diodes.
Reliable laboratory power supply

Manufacturing

At the bottom of the case we mark, we drill holes for: a transformer, a diode bridge, a module. Everything is soldered according to the scheme.With the module dropped two trimming resistors. Instead, he soldered wires. For current 3 wires, for voltage two.
Reliable laboratory power supply
I will power the voltmeter through a 5 volt linear regulator. Diode bridge КЦ402 and a small capacitor.
Reliable laboratory power supply
On the back panel I make markup for the network connector and fuse. I carefully cut and install everything.
Reliable laboratory power supply
On the front panel I mark out and cut out all the holes. There will be: output terminals, a power switch, current and voltage resistors, a voltammeter.
Reliable laboratory power supply
Soldered all elements installed from the inside. The power switch commutes both power wires. Originally wanted to apply another.
Reliable laboratory power supply
We install all the elements of the front panel. The plus terminal is marked in red. Handles resistors of different colors. Red by color display volt. Yellow current. So far, not signed where the current and voltage.Later I will change the resistors for multiturn, the pens may also be changed.
Reliable laboratory power supply
The top cover is painted. There was too big a gap between the front panel and the lid, it was covered with a small corner. During the test, the unit produced 9 amperes at a short, at 28 Volts, which was slightly more than 250 watts.
Reliable laboratory power supply
This is what the Laboratory Power Unit turned out to be. They can both power up all sorts of devices, also charge batteries. Initially, I wanted to use a 24 volt pulse source, but I found a transformer of the correct size. I also try to assemble a device from what it is.


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