Author Archives: DP

Build your own HF balun

via Dangerous Prototypes

Miguel, EA4EOZ, posted this great DIY tutorial on building your own balun:

A balun is a MUST for dipoles or similar antennas when they are feed with coaxial cables. Many hams connect the center conductor of the coaxial cable to one side of the dipole, and the shield to the other. Wrong!
From the RF point of view, the shield can be modeled as two conductors, the internal shield (the real shield, this is, ground) and the external shield, who is really far to be ground. In this way, your dipole has 3 arms, the two from the dipole and the coaxial cable shield (external face).

See the full post on EA4EOZ blog.

App note: Charging capacitive loads with eFuse

via Dangerous Prototypes

App note from ON Semiconductors on how eFuse manage to cope up with large capacitive loads. Link here (PDF)

The eFuse protection devices are used for limiting the system load current in the events of overload or short circuit. Many applications employ On Semiconductor eFuses at the power input stage of the system between the main power input connector and DC−DC converters or power regulators. The systems utilizing eFuse protection devices at the power input stage may represent inductive, resistive, capacitive or mixed types of loads.
One of the common load characteristics for various systems is large capacitive load, typically starting from 1mF all the way to few hundred milli Farads. The challenge presented by such load to an overcurrent protection system is large inrush current due to the excessive capacitance which will cause the device to shut down during startup.

App note: Tuning linear redrivers

via Dangerous Prototypes

App note from ON Semiconductors about linear redrivers setting. Linear redrivers are used in systems in order to improve high speed signal integrity in systems transmitting digital data. Link here (PDF)

Linear redrivers are used in many applications that transmit data at high speeds. They can be found on computer motherboards, gaming consoles, graphics cards, cables, and any other environment that transmits digital data. More specific examples of common applications using linear redrivers include USB, DisplayPort, HDMI, PCIe, and SATA ports.

App note: Tutorial selecting the optimum voltage reference

via Dangerous Prototypes

App note from Maxim Integrated guiding you when selecting voltage references. Link here

What could be more basic than a voltage reference – a simple, constant reference voltage? As with all design topics, there are tradeoffs. This article discusses the different types of voltage references, their key specifications, and the design tradeoffs, including accuracy, temperature-independence, current drive capability, power dissipation, stability, noise, and cost.

App note: Voltage Reference Application and Design Note

via Dangerous Prototypes

App note from Renesas on the basics of voltage reference. Link here (PDF)

Conceptually, a voltage reference is a very simple device with only one purpose in its life. Quite simply, the purpose of a voltage reference is to generate an exact output voltage no matter what happens with respect to its operating voltage, load current, temperature changes or the passage of time.

DIY OpenDPS power supply

via Dangerous Prototypes

Evan’s DIY OpenDPS power supply:

Years ago I heard about the OpenDPS project to give open source firmware to cheap and available chinese power supplies. These aren’t strictly whole power supplies, they are configurable CC and CV buck converters. That means that it needs a stable DC source to back it to be used as a bench power supply. Perhaps you may not want to do this if you intend to use the DPS as a battery charger run from a solar supply or something, but most people I see want to use them for bench supplies so that requires an existing DC supply. Today I finally finished mine.