EK009 Bipolar Power Supply LM317/LM337
Part no: 41016260
EK009 is a bipolar (dual) adjustable voltage regulator with full-wave rectification, built around the classic regulators LM317 and LM337.
The input voltage can be an unregulated dual DC supply or AC from a transformer with dual secondary windings (center tap).
It is also possible to use a transformer without a center tap, but with significantly reduced output current and voltage when using the same filter capacitors and input voltage. If EK009 is powered from a transformer without a center tap, diodes D2 and D4 must not be mounted.
If the board is powered with an unregulated DC supply, diodes D1, D2, D3, and D4 must not be mounted. Instead, jumpers should be installed in the positions for D1 and D3.
Voltage regulation is handled by the linear regulators LM317 and LM337 for positive and negative voltage respectively. To maintain stable and low-ripple outputs, the input voltage must be at least 3V higher than the desired output voltage. However, the difference between input and output voltage should be kept as low as possible to minimize heat dissipation in the regulators.
The output voltage for each rail is adjusted using the trimmer potentiometers on the board. The positive and negative outputs can be set independently from 1.3 to 30V.
- Output voltage: ±1.3 - ±30VDC
- Max current draw: 1.5A
- Dimensions: 63.5 x 50.8mm
- Mounting holes: c-c 58.42 x 45.72mm, ø2.54mm
Component list
| RefDes | Value | Qty. | Part.no. | Marking |
|---|---|---|---|---|
| CON1, CON2 | Screw terminal 3-pol 5mm | 2 | 41016291 | |
| C1, C2, C9, C10 | Ceramic 100nF | 4 | 41003038 | 104 |
| C3, C4, C5, C6 | El.lyt 10uF | 4 | 40520021 | 10uF |
| C7, C8 | El.lyt 4700uF | 2 | 41016024 | 4700uF |
| D1 - D8 | Diode 1N4004 | 8 | 40310004 | |
| R3, R4 | Resistor 200ohm | 2 | 40811220 | |
| R5, R6 | Resistor 3kohm | 2 | 40811330 | |
| R7, R8 | Trim pot 5k 3266Y | 2 | 40900450 | 502 |
| U1 | Positive regulator LM317T | 1 | 40350028 | LM317T |
| U2 | Negative regulator LM337T | 1 | 40350337 | LM337T |
| LED+ | LED 3mm grön | 1 | 40307003 | |
| LED- | LED 3mm röd | 1 | 40307000 | |
| M1, M2 | Heatsink TO-220 | 2 | 41016259 | |
| Screw M3 6mm | 2 | 41010772 | ||
| Hex nut M3 | 2 | 41010787 |
Assembly guide
Before starting assembly, check that the PCB is free from damage and scratches. Verify that all components to be assembled are present, compare with the component list.
It is usually easiest to start assembling the lowest profile components and work upwards in size. IC sockets, resistors, ceramic capacitors and diodes are mounted first. Electrolytic capacitors, connectors and potentiometers are mounted last.
For some components, correct orientation is important. Pay attention to the markings on the PCB.
Interactive assembly guide ↗
Wiring guide
Warning
Take extreme caution when wiring the transformer primary winding to 230VAC.
The primary side (high voltage) must be wired with a fuse rated for 230VAC and the appropriate current. Isolate all exposed joints. Ground metal chassis parts to safety ground.
The board can be powered in three different ways: with a transformer with dual secondary windings (center tap), a transformer with a single secondary winding, or with a DC supply.
Depending on the type of source used, the board must be populated accordingly.
The best option is to use a transformer with dual secondary windings. This provides the lowest ripple at high load current.
All four diodes for the rectifier bridge should be installed. The outer connections from the transformer’s secondary side should be connected to AC+ and AC-. The common connection from the two windings should be connected to GND.
If a transformer with a single secondary winding is used, only diodes D1 and D3 should be installed. The two wires from the transformer should be connected to AC+ and AC-.
It is also possible to use a DC supply. No diodes for the rectifier bridge need to be installed. Instead, D1 and D3 should be bridged using a piece of wire or a component lead.
Schematic
Drawing
