Giving place to the more advanced products in droves complete its "life cycle" of a computer device, the release of the 90-ies of the last century.
So, for example, to fade into history matrix printers, supplanted by printers with inkjet and laser principles of printing. Not all nodes are equally dot matrix printers subject to wear and aging, so when disassembling these printers for parts there is a sense to use in other devices, some of their operational sites.
Most dot-matrix printers were manned sufficiently powerful and compact switch mode power supplies, which can be used in Amateur designs.
After disassembly of the next dot-matrix printer in my hands was pulsed the power supply from the printer "Epson" release 1998 (Fig.1).
Unfortunately, the exact name of the printer could not be determined, but the fee PSU marked "EPS-IIE C076 PSE". The power supply has two output voltage: +34 And +5,1 V. the Voltage +5.1 V is obtained from the voltage +34 In using a secondary switching regulator. The onboard oxide capacitor 120 µf with an operating voltage 400 V clearly indicates that the power supply is designed to connect to the network 220.
Having tested the unit, I found that he is able to give to the load current about 2.5 And the chain of +34 and In about 1 And circuit +of 5.1 V.
These options allow you to use this PSU to power the stereo amplifier power output 15...18 watts per channel, built according to the scheme with single-supply. Voltage 5.1 V can be used to power the nodes management of USC, built-in radio, MP-3 player.
Unlike most of the "television" of the power supply, this power supply keeps resistance to change in load current from maximum to zero.
To power USC from such or similar PSU should be made uncomplicated LC filter, the circuit of which is shown in Fig.2. In the PD in the channel 34 during there are two oxide capacitor C51 and C52 with a capacity of 3300 UF each (Fig.1), but there is no filter ripple and noise choke. In additional block (Fig.2) voltage +34 passes through two LC filter consisting of choke L1, L3 and capacitors C3, C5, C6. Also passes additional filtering and voltage +5,1 V. Fuses or resettable fuses FU1, FU2 protect the unit from overload. Inductors can be wound on the rings of low-frequency ferrite with an outside diameter of 15 to 20 mm. They contain 15...25 turns stranded bonding wire.
Chassis-USC switching power supply, it is desirable to put in screen made of perforated sheet. If USC at maximum volume mounted on heatsinks in the PSU power MOSFET Q1 and powerful diode Schottky D51 will be heated above 60°C, it is desirable to tie more effective tapoatafa that will increase the reliability of PD.
Similar switching power supplies from a legacy computer equipment can to apply not only to power USC, but also for other electrical and radio engineering, for example, a power drill, low-voltage soldering iron, large digital display, etc.
Author: A. Butov, S. CORBA Yaroslavl region