Multi-Range Programmable DC Power Supplies

B&K9115_leftB&K Precision expanded its 9115 series with the addition of two new multi-range programmable DC power supplies: the 9115-AT and the 9116. Similar to the 9115, the new models deliver full 1,200-W output power in any combination of voltage and current within the rated limits. The models offer the same features as the 9115, but with a few differences.

The 9115-AT provides unique built-in automotive test functions that can simulate common test conditions to ensure reliability of electrical and electronic devices installed in automobiles. The 9116 offers a higher voltage range up to 150 V. Both models are suitable for automotive and a variety of benchtop or automated test equipment (ATE) system applications.

B&K9116_rearThe 9115-AT and the 9116 include a high-resolution vacuum fluorescent display (VFD), independent voltage and current control knobs, cursors, and a numerical keypad for direct data entry. Both models also provide internal memory storage to save and recall up to 100 different instrument settings, sequence (list mode) programming, and configurable overvoltage and overpower protection limits. The 9115 series offers remote control software for front-panel emulation, generation and execution of test sequences, and logging measurements via a PC.

The 9115-AT and 9116 cost $2,345 and $1,995, respectively.

B&K Precision Corp.
www.bkprecision.com

Small, Self-Contained GNSS Receiver

TM Series GNSS modules are self-contained, high-performance global navigation satellite system (GNSS) receivers designed for navigation, asset tracking, and positioning applications. Based on the MediaTek chipset, the receivers can simultaneously acquire and track several satellite constellations, including the US GPS, Europe’s GALILEO, Russia’s GLONASS, and Japan’s QZSS.

LinxThe 10-mm × 10-mm receivers are capable of better than 2.5-m position accuracy. Hybrid ephemeris prediction can be used to achieve less than 15-s cold start times. The receiver can operate down to 3 V and has a 20-mA low tracking current. To save power, the TM Series GNSS modules have built-in receiver duty cycling that can be configured to periodically turn off. This feature, combined with the module’s low power consumption, helps maximize battery life in battery-powered systems.

The receiver modules are easy to integrate, since they don’t require software setup or configuration to power up and output position data. The TM Series GNSS receivers use a standard UART serial interface to send and receive NMEA messages in ASCII format. A serial command set can be used to configure optional features. Using a USB or RS-232 converter chip, the modules’ UART can be directly connected to a microcontroller or a PC’s UART.

The GPS Master Development System connects a TM Series Evaluation Module to a prototyping board with a color display that shows coordinates, a speedometer, and a compass for mobile evaluation. A USB interface enables simple viewing of satellite data and Internet mapping and custom software application development.
Contact Linx Technologies for pricing.

Linx Technologies
www.linxtechnologies.com

Dual-Channel Waveform Generators

B&K Precision 4053 Waveform Generator

B&K Precision 4053 Waveform Generator

The 4050 Series is a new line of four dual-channel function/arbitrary waveform generators. The instruments can generate 5-to-50-MHz waveforms for applications requiring stable and precise sine, square, triangle, and pulse waveforms with modulation and arbitrary waveform capabilities.

All models provide a main output voltage that can be vary from 0 to 10 VPP into 50 Ω and a secondary output that can vary from 0 to 3 VPP into 50 Ω. The generators feature a 3.5” color LCD, a rotary control knob, and a numeric keypad with dedicated waveform keys and output buttons.

The 4050 Series provides users with 48 built-in arbitrary waveforms. Using the included waveform editing software via the standard USB interface on the rear, users can create and load up to 10 custom 16-kpt waveforms. For general-purpose interface bus (GPIB) connectivity, an optional USB-to-GPIB adapter is available.

The generators offer a variety of modulation schemes for modulated signal applications including amplitude and frequency modulation (AM/FM), double sideband amplitude modulation (DSB-AM), amplitude and frequency shift keying (ASK/FSK), phase modulation (PM), and pulse-width modulation (PWM). Additional standard features include a linear and logarithmic sweep function, a built-in counter, sync output, a trigger I/O terminal, and a USB host port on the front panel to save and recall instrument settings and waveforms. A standard external 10-MHz reference clock input is provided to synchronize the instrument to another generator.

The 4052 (5-MHz) costs $499, the 4053 (10 MHz) costs $599, the 4054 (25 MHz) costs $850, and the 4055 (50 MHz) costs $1,050. Note: B&K Precision is offering 10% off MSRP through November 30, 2013. See website for details.

B&K Precision Corp.
www.bkprecision.com

PC-Programmable Temperature Controller

Oven Industries 5R7-388 temperature controller

Oven Industries 5R7-388 temperature controller

The 5R7-388 is a bidirectional temperature controller. It can be used in independent thermoelectric modules or in conjunction with auxiliary or supplemental resistive heaters for cooling and heating applications. The solid-state MOSFET output devices’ H-bridge configuration enables the bidirectional current flow through the thermoelectric modules.
The RoHS-compliant controller is PC programmable via an RS-232 communication port, so it can directly interface with a compatible PC. It features an easily accessible communications link that enables various operational mode configurations. The 5R7-388 can perform field-selectable parameters or data acquisition in a half duplex mode.

In accordance with RS-232 interface specifications, the controller accepts a communications cable length. Once the desired set parameters are established, the PC may be disconnected and the 5R7-388 becomes a unique, stand-alone controller. All parameter settings are retained in nonvolatile memory. The 5R7-388’s additional features include 36-VDC output using split supply, a PC-configurable alarm circuit, and P, I, D, or On/Off control.

Contact Oven Industries for pricing.

Oven Industries, Inc.
www.ovenind.com

FET Drivers (EE Tip #105)

Modern microprocessors can deliver respectable currents from their I/O pins. Usually, they can source (i.e., deliver from the power supply) or sink (i.e., conduct to ground) up to 20 mA without any problems. This allows the direct drive of LEDs and even power FETs. It is sufficient to connect the gate to the output of the microprocessor (see Figure 1).

Elektor, 060036-1, 6/2009

Elektor, 060036-1, 6/2009

Driving a FET from a weaker driver (such as the standard 4000 series) is not recommended. The FET would switch very slowly. That is because power FETs have several nanofarads of input capacitance, and this input capacitance has to be charged or discharged by the microprocessor output. To get an idea of what we’re talking about: the charge or discharge time is roughly equal to V × C/I or 5 V × 2 × 10-9/(20 × 10-3) = 0.5 ms.

Not all that fast, but still an acceptable switching time for a FET. However, not every FET is suitable for this. Most FETs can switch only a few amps with a voltage of only 5 V at their gate. The so-called logic FETs do better. They operate well at lower gate voltages.

So take note of this when selecting a FET. To make matters worse, many modern microprocessor systems run at 3.3 V and even a logic FET doesn’t really work properly any more. The solution is obviously to apply a higher gate voltage.

This requires a little bit of external hardware, as is shown in Figure 2, for example. The microprocessor drives T1 via a resistor, which limits the base current. T1 will conduct and forms via D1 a very low impedance path to ground that quickly discharges the gate.

Elektor, 060036-1, 6/2009

Elektor, 060036-1, 6/2009

When T1 is off, the collector voltage will rise quickly to 12 V, because D1 is blocking and the capacitance of the gate does not affect this process. However, the gate is connected to this point via emitter follower T2. T2 ensures that the gate is connected quickly and through a low impedance to (nearly) 12 V.

In the example, a voltage of 12 V is used, but this could easily be different. Note that if you’re intending to use the circuit with 24 V, for example, most FETs can tolerate only 15 or 20 V of gate voltage at most. It is therefore better not to use the driver with voltages above 15 V. We briefly mentioned the 4000 series a little earlier on. There are two exceptions. The 4049 and 4050 from this series are so-called buffers, which are able to deliver a higher current (source about 4 mA and sink about 16 mA). In addition this series can operate from voltages up to 18 V. This is the reason that a few of these gates connected in parallel will also form an excellent FET drive (see Figure 3). When you connect all six gates (from the same IC!) in parallel, you can easily obtain 20 mA of driving current.

Elektor, 060036-1, 6/2009

Elektor, 060036-1, 6/2009

This looks like an ideal solution, but unfortunately there is a catch. Ideally, these gates require a voltage of two thirds of the power supply voltage at the input to recognize a logic one. In practice, it is not quite that bad. A 5-V microprocessor system will certainly be able to drive a 4049 at 9 V. But at 12 V, things become a bit marginal!

—Elektor, 060036-1, 6/2009