New AC Source with Power Line Disturbance Simulator

B&K Precision recently introduced the 9801 AC power source, which is a compact 19″ half-rack, single-phase AC source that outputs up to 300 VA and measures AC power characteristics. You can operate the AC source in a 0-to-300-V continuous sweep range or 150-V/300-V auto-switching range with adjustable start and stop phase angle control. With a built-in power line disturbance (PLD) simulator, list, sweep, and dimmer mode, the 9801 is suitable for simulating various AC power conditions. It provides a complete solution for manufacturing, R&D, and precompliance testing applications.9801_front-B&K

For certain compliance testing applications, manufacturers may need an AC source to simulate various AC power line outlets and disturbances. This includes evaluating a product’s immunity to less than ideal input voltage situations such as dips, surges, and dropouts. Therefore, programmable AC sources with built-in power line disturbance simulation functions can be an invaluable tool for testing devices under these conditions.

The 9801 features a low distortion, single-phase AC output with programmable RMS voltage up to 300 V, maximum RMS current up to 3 A, and adjustable frequency from 45 to 500 Hz. The power source is also capable of delivering up to 12-A peak current.

Provided on the front panel is a universal AC output socket and an easy-to-use rotary knob to set AC waveform parameters. The bright VFD display continuously displays the output voltage, peak and RMS current, frequency, power factor, apparent/true power, and elapsed time. The rear includes an additional AC output terminal block for wire connection and an external BNC connector for output On/Off control and monitoring, external triggering, and synchronization. Users will also benefit from the 9801’s standard RS-232, USBTMC-compliant USB, and LAN interfaces for remote control and programming.

Built-in simulation functions include list mode with PLD simulator, sweep, and phase-cut dimming output. The simulation modes allow users to program varying steps of voltage, frequency, width, slope, and disturbances, sweep the output voltage and frequency, and control the phase cut-off of the AC sine wave’s leading or trailing edge. For pre-compliance testing, voltage fluctuations and frequency simulations can be set up according to IEC61000-4-11, IEC61000-4-14, and IEC61000-4-28.

Furthermore, the 9801 provides several protection features: overvoltage (OVP), overcurrent (OCP), overpower (OPP), and overtemperature (OTP) protection, settable voltage and frequency limits, key lock function, and RMS/peak current protection settings to shut off the output when a load exceeds the set current.

B&K Precision’s 9801 AC power source costs $1,995.

Source: B&K Precision

 

 

Simple Guitar Transmitter (EE Tip #102)

You need a guitar amplifier to play an electric guitar. The guitar must be connected with a cable to the amplifier, which you might consider an inconvenience. Most guitar amplifiers operate off the AC power line. An electric guitar fitted with a small transmitter offers several advantages. You can make the guitar audible via an FM tuner/amplifier, for example. Both the connecting cable and amplifier are then unnecessary. With a portable FM broadcast radio or, if desired, a boombox, you can play in the street or in subway.

Source: Elektor 3/2009

Source: Elektor 3/2009

stations (like Billy Bragg). In that case, everything is battery-powered and independent of a fixed power point. (You might need a permit, though.)

Designing a transmitter to do this is not necessary. A variety of low-cost transmitters are available. The range of these devices is often not more than around 30′, but that’s likely plenty for most applications. Consider a König FMtrans20 transmitter. After fitting the batteries and turning it on, you can detect a carrier signal on the radio. Four channels are available, so it should always be possible to find an unused part of the FM band. A short cable with a 3.5-mm stereo audio jack protrudes from the enclosure. This is the audio input. The required signal level for sufficient modulation is about 500 mVPP.

If a guitar is connected directly, the radio’s volume level will have to be high to get sufficient sound. In fact, it will have to be so high that the noise from the modulator will be quite annoying. Thus, a preamplifier for the guitar signal is essential.

To build this preamplifier into the transmitter, you first have to open the enclosure. The two audio channels are combined. This is therefore a single channel (mono) transmitter. Because the audio preamplifier can be turned on and off at the same time as the transmitter, you also can use the transmitter’s on-board power supply for power. In our case, that was about 2.2 V. This voltage is available at the positive terminal of an electrolytic capacitor. Note that 2.2 V is not enough to power an op-amp. But with a single transistor the gain is already big enough and the guitar signal is sufficiently modulated. The final implementation of the modification involves soldering the preamplifier circuit along an edge of the PCB so that everything still fits inside the enclosure. The stereo cable is replaced with a 11.8″ microphone cable, fitted with a guitar plug (mono jack). The screen braid of the cable acts as an antenna as well as a ground connection for the guitar signal. The coil couples the low-frequency signal to ground, while it isolates the high-frequency antenna signal. While playing, the cable with the transmitter just dangles below the guitar, without being a nuisance. If you prefer, you can also secure the transmitter to the guitar with a bit of double-sided tape.

—Gert Baars, “Simple Guitar Transmitter,” Elektor,  080533-1, 3/2009.