Vermes
Advanced Member level 4
Some of the elements:
- filtering capacitor 10000uF
- two transistors BD249C with compensatory emitter resistors (0R1 10W)
- BD139 with a radiator
- two resistors 0R51 10W connected in parallel
- rectifier bridge of a great power
The power supply and multimeter boards were home made by thermal transfer method, output and thermal protection were drawn with nail lacquer.
Housing used was metal and solid T-74. Heat sink is 8cm high. All the mechanical treatment was made at home using multigrinder, bench drill and other small tools such as punch or files. On the front of the housing, self-adhesive foil with a print was glued (panel designed in Front Designer).
Additionally the power supply has:
- system enabling the output (you can set the values of current and voltage with connected load and then enable those values to the output)
- thermal protection (disconnects the main transformer and the power supply after reaching the temperature of 80 degrees Celsius, and enables it when the temperature drops to 60 degrees Celsius)
- fan control (via regulator on LM317t with a thermistor)
To power the power supply, it uses toroidal transformer 2x12V 250W (secondary windings connected in series), when the system enabling the output, thermal protection, fan control and multimeter are powered from a separate pulse power supply 12V 700mA.
Elements used:
- main transformer
- pulse power supply
- laminate
- housing
- heat sink
- connectors, cables
- fans
- electronic parts
The power supply was tested without fans with 6A load at 12V. Additionally, an electronic thermometer was connected near the power transistor. When the temperature reached 80 degrees Celsius, the system disconnected the power supply, so the thermal protection proved to be working. Then the fans were inserted, controller regulated and tested the same way. The power supply did not reach the value of temperature at which it should disconnect, it operated normally and did not heat up too much. The ouptut voltage drops a little, when loaded 2A at 12V, you have 11,97V at the output.
Link to original thread (useful attachment) – Zasilacz warsztatowy 0-32V 0.002-6A