Gathering another project, I ran into the problem of powering the device. The computer unit is no longer enough for voltage. Then I remembered the DC-DC converter board.
As a simple voltage regulator is quite suitable.
For homemade we will need:
- step-down transformer in the housing;
- ;
- terminals;
-
- adjustment resistor;
- network switch;
- voltage stabilizer at 12V;
- diode bridge;
- electrolytic capacitor;
- wires, tools.
As a step-down transformer, I used the transformer lying in my case in the case. What he is from, I don’t remember. At the output, it has a voltage of 17.9 V, at a current of 1.7 A. In principle, anyone with similar parameters will do. Since the transformer is in the housing, the manufacture and selection of the latter have disappeared by themselves.
The step-down DC-DC converter applied ready-made, bought in China. It is small in size and has good stabilization. About this converter is full of information on the Internet.
As a rectifier, I used a ready-made diode bridge. As a filtering capacitor, I used a copy of 35 V and a capacity of 2200 μF.
I will put the terminals domestic carbolitic, taken from the old device. Also under them I found small pieces of wire with ferrules.
Since the tuning resistor is installed on the board, an adjustment is needed to place it on the board. In his quality, he used a bu, with a nominal value slightly less than that on the board. Rating 4.7 kOhm. I used the handle on the resistor from the old tube TV.
I use a voltmeter from China. The dimensions are small and pretty good accuracy, for this unit is quite suitable.
Assembly process.
The scheme is very simple. Collect it is not difficult.
We solder the diode bridge to the transformer. He curved the legs of the bridge in a special way. The filter capacitor soldered to the bridge. He climbed perfectly, the height of the transformer.
The output wires with lugs were soldered to the DC-DC converter board. The trimmer resistor also soldered off and soldered the wires instead. I solder the external resistor during installation on the case.
The voltmeter has three soldered wires.Yellow and black, respectively + and -, supplying the voltmeter itself. Red and black measuring. If the voltmeter is powered from the output terminals, then the indication lights up from about 4 volts. This does not suit me. Therefore, I will use the domestic stabilizer chip K142EN8V. It provides 12 V, it is quite suitable for powering a voltmeter. You can use any stabilizer from 5-12V. For example, L7805 (5 V), L7812 (12 V).
I solder the wires to the microcircuit and power it from the output of the diode bridge. I fasten the transformer with a long screw. Such a heat dissipation, although the microcircuit does not heat up.
I mark out all the holes and cutouts on the case. I drill and cut everything.
First I install a voltmeter and one output terminal. I removed the insulators from the terminal, the case is plastic, they are not needed here.
I install the second terminal and resistor at the junction of the case. When closing the case, everything will be perfectly clamped. I solder the DC-DC converter module. Neatly fit.
I install a switch on the back of the case. He removed it from the old computer power supply. Also, a fuse was installed on the transformer, it did not display it in the photo.
Plus terminal highlighted with nail polish.
The minimum voltage is obtained from:
Before:
Here's a power supply turned out. Maximum load current of about 1.5 A. Holds current perfectly.
A detailed assembly of the power supply is displayed on the video: