Microelectronics | Triple Power Supply

Synopsis

Having a Hameg HM8030 function generator module, I decided that I will build a power supply for it. Of course, I could've bought a Hameg base station, but that would've been costly, and I am not that much into Hameg gear. Thus, I thought that a DIY approach would also make for a nice project.

After reading the official Hameg documentation, I learned that the power supply must have the following characteristics.

+16.0 V / 300 mA; provisioned for 400 mA
-16.0 V / 250 mA; provisioned for 400 mA
+5.0 V / 200 mA; provisioned for 300 mA

So I chose to slightly overbuild the mains power transformer. This way, each secondary winding current is around 100 mA larger than the necessary for the HM8030.

I decided to go for a linear approach, with individual voltage regulators. The well-known duo of LM317 and LM337 are candidates for the ±16 V. For the TTL power supply, I went with the classic LM7805. The power transformer voltage for the secondary winding #1 is 8 V / 300 mA, and for the secondary winding #2 is 18 V / 400 mA - 0 V - 18 V / 400 mA. The latter secondary winding has a center tap. After rectification and adjustments, this power supply will output the voltages specified within the Hameg documentation.

The construction of this power supply is simple, as revealed by the electrical schematic diagram. As for the circuit board layout, I took into consideration that linear regulators require heat sinks. I decided to use electrolytic capacitors rated at 105 °C, made by Vishay. Regarding the 100 nF capacitors, I just chose standard polyester film. These help cut high-frequency stray currents that might (or might not) be traveling around the supply circuit traces. The 10 uF capacitors are tantalum.

Schematic Diagram

Let's start by taking a look at the schematic diagram.

Fig. 1: Electrical Schematic Diagram

Fig. 2: Bottom Layer Printed Circuit Board

Fig. 3: Top Layer Printed Circuit Board - Simulation

Fig. 4: Bottom Layer Printed Circuit Board - Simulation

Files

In case you'd like to build this project using DIY methods, the PDF file contains the 1:1 mirrored circuit layout.

psu-hm8030-bottom.pdf (mirrored circuit layout)

Construction and Pictures

This is the mains power transformer.

Unfortunately, I sold the function generator, and bought one made by Hewlett Packard instead. Thus, I abandoned this project. I sold the transformer together with the HM8030 module.

I decided to keep this documentation, maybe it helps you in some way.