Velleman K8042 Symmetric 1A Power Supply

Features & Specifications

Features

• Low cost universal symmetric power supply.
• Requires a suitable transformer and heatsink (not included).
• Ideal for applications such as op-amp circuits and amplifiers.
• Trimmers allow continuous adjustment of output voltage.
• Includes LED output indicators.
• Compact size.

Specifications

• Positive and negative output adjustable between 1.2VDC and 24VDC.
• Output current: up to 2 x 1A continuous (with suitable heatsink).
• Maximum input voltage: 2 x 24VAC.
• Very good line and load regulation.
• Low ripple.
• Short circuit protection.
• Thermal protection.
• Optional heatsink: HS4003 (for maximum 20W dissipation).
• Dimensions: 78 x 52 x 24mm (3.1" x 2.0" x 0.9").

Assembly Hints

1. Assembly (Skipping this can lead to troubles!)

Read these hints carefully to ensure successful project completion.

1.1 Tools Required

• A good quality soldering iron (25-40W) with a small tip. [?]
• Wet sponge or cloth for cleaning the soldering iron tip. Applying solder to the tip (tinning) protects it and ensures good connections.
• Thin raisin-core solder. Avoid flux or grease.
• A diagonal cutter to trim excess wires. Hold leads to prevent them from flying towards eyes. [✂️]
• Needle nose pliers for bending leads or holding components. [?]
• Small blade and Phillips screwdrivers. [?️]
• A basic multi-meter may be required or handy for some projects. [0.000]

1.2 General Assembly Hints

• Ensure your skill level matches the project complexity.
• Follow instructions carefully; understand each step before performing it.
• Perform assembly in the correct order as stated in this manual.
• Position all parts on the PCB (Printed Circuit Board) as shown in the diagrams.
• Values on the circuit diagram are subject to changes.
• Values in this assembly guide are correct*.
• Use the check-boxes to mark your progress. [✔️]
• Read the included information on safety and customer service.

* Typographical inaccuracies excluded. Always check for last-minute manual updates indicated as 'NOTE' on a separate leaflet.

1.3 Soldering Hints

1. Mount the component against the PCB surface and carefully solder the leads.
2. Ensure solder joints are cone-shaped and shiny.
3. Trim excess leads as close as possible to the solder joint.

Important Note: AXIAL COMPONENTS ARE TAPED IN THE CORRECT MOUNTING SEQUENCE! REMOVE THEM FROM THE TAPE ONE AT A TIME!

You can find the color code for resistances and LEDs on our website: http://www.velleman.be/common/service.aspx

Component Identification

• 1. Jump wire: J
• 2. Diodes (Polarity Sensitive):
  • D1-D10: 1N4007. Diagram shows diode symbol with cathode indicated.
• 3. Resistors:
  • R1, R2: 120 Ohm (Color Code: 1-2-1-B)
  • R3, R4: 2K2 Ohm (Color Code: 2-2-2-B)
• 4. Capacitors (Non-Polarized):
  • C3, C4: 100nF (104)
• 5. Trim Potentiometers:
  • RV1, RV2: 2K2 Ohm (2K5)
• 6. Terminal Blocks:
  • SK1, SK2: 2-pin
  • SK3: 3-pin
• 7. LEDs (Polarity Sensitive):
  • LD1, LD2: 3mm Red. Diagram shows LED symbol with anode and cathode marked.
• 8. Electrolytic Capacitors (Polarity Sensitive):
  • C5, C6, C7, C8: 10µF
  • C1, C2: 1000µF. Diagram shows electrolytic capacitor symbol with polarity marked.
• 9. Voltage Regulators:
  • VR1: LM317
  • VR2: LM337

Construction and Assembly

10. Heatsink Installation

To use the maximum 20W dissipation, mount the optional heatsink (ordernr. HS4003).

1. Apply a little heat conducting paste to one side of an insulation plate. Press this side against the heatsink where the component will be fitted. Diagram shows heatsink, insulation plate, insulation tube, M3 bolt, and M3 nut.
2. Apply a little heat conducting paste to the component itself. Fit the component onto the heatsink and secure it using an insulation tube, a 15mm M3 bolt, and a nut.
3. Fit the components and heatsink assembly onto the PCB and secure it with two 5mm spacers and two screws. Diagram shows PCB with heatsink assembly attached.
4. Solder the connections of the voltage regulators. Diagram shows soldering process.

11. Using a Metal Enclosure as a Heatsink

When mounting the kit into an enclosure, drill two holes in the backside of the housing to pass the 15mm M3 bolts through. Diagram illustrates this process with heat conducting paste, insulation plate, and insulation tube.

12. Connection

Connect the mains input (transformer) and output terminals as shown.

Diagrams show connections for mains input via a toroidal transformer or a standard transformer, and connections to the PCB terminals (VA, VB, GND). Also shows battery connection for testing.

Diagrams show PCB terminals VA, 0, VB, and GND, and terminal blocks SK1, SK2.

13. PCB Layout

Diagram showing the component placement and silkscreen markings on the Velleman P8042'1 PCB. Includes placement for voltage regulators (VR1, VR2), capacitors (C1-C8), diodes (D1-D10), resistors (R1-R4), potentiometers (RV1, RV2), LEDs (LD1, LD2), and terminal blocks (SK1-SK3). Indicates optional heatsink mounting points and DC output terminals.

14. Diagram

Schematic diagram of the Velleman K8042 Symmetric 1A Power Supply circuit. It details the connections between the AC input, rectifier diodes (D1-D4), filter capacitors (C1, C2), voltage regulators (VR1: LM317, VR2: LM337), output capacitors (C5-C8), current limiting resistors (R1-R4), potentiometers (RV1, RV2) for voltage adjustment, and output LEDs (LD1, LD2).

Manufacturer Information

VELLEMAN NV

Legen Heirweg 33, B-9890 GAVERE

Belgium (Europe)

Modifications and typographical errors reserved © Velleman nv.

Barcode: 5410329327132