Data Logging

Many applications require high-resolution, multichannel, large-bandwidth signal acquisition. Some examples are vibration analysis, vehicle telemetry, and telecommunications. You could use an array of A/D converters to address such applications, but ADCs are costly and consume considerable board space. Figure 1 shows a complete and cost-effective, high-speed, differential, eight-channel, 12-bit acquisition system that uses few parts.

The USB has become the interface of choice for connecting to PCs. Available on all relatively modern PCs, the USB offers a standard connector and can supply power to peripherals at 5V and as much as 100 mA of current. The circuit in Figure 1 combines Maxim's (www.maxim-ic.com) MAX1168, a low-power, 16-bit ADC, with a small USB-interface module to make a simple, eight-channel, 16-bit measurement system. The MAX1168 includes eight input channels, an SPI (serial-peripheral-interface) port, a 4.096V reference, and a clock oscillator.

The asynchronous RS-232C interface is a simple, low-cost option for interconnecting processor-based systems. In many applications, you need to transfer variable-size messages. However, the character-oriented RS-232C protocol offers no direct mechanism for transferring messages as self-contained packets. The method described here uses an obscure feature found in most UART devices to indicate packet boundaries.

This is the electronic schematic of the homebuilt SONAR. Only one piezoelectric tranducer is used for both tramsmit & receive. This transducer is switched from TX to RX via the four 4016 switches. A high gain amplifier stage & rectifier translates the received echoes into voltage pulses. The timing is controlled by the PIC12C508 8-pin microcontroller as it is shown in the following figure:

This circuit changes the change of the resistance value into the change of the voltage using the transistor. Then, it compares that voltage and the voltage of the setting temperature using the voltage comparator and it drives a relay. It is a relatively simple circuit. With this circuit, the difficult point is to handle an analog signal (the temperature change).

This circuit uses an LM11 to form a voltage follower with 1G ohm input resistance built using standard resistor values. With the input disconnected, the input offset voltage is multiplied by the same factor as R2; but the added error is small because the offset voltage of the LM11 is so low. When the input is connected to a source less than 1G ohm, this error is reduced. For an ac-coupled input a second 10M resistor could be connected in series with the inverting input to virtually eliminate bias current error; bypassing it would give minimal noise.

This is a simple but reliable circuit for your sump-pump, aquarium, boat, or whatever, but water only. Please be careful when working with 115Volt line voltage! Take every precaution to avoid electrical shock. Unplug the power before making changes or touching resistor R1.

The circuit is designed to be low cost. It uses a PIC12C508 to perform the control functions and standard 40khz piezo transducers. The drive to the transmitting transducer could be simplest driven directly from the PIC. The 5v drive can give a useful range for large objects, but can be problematic detecting smaller objects. The transducer can handle 20v of drive, so I decided to get up close to this level. A MAX232 IC, usually used for RS232 communication makes and ideal driver, providing about 16v of drive.

This application note describes the evaluation board for the AD7890 12-bit serial data acquisition system. The AD7890 is an eight-channel 12-bit data acquisition system which operates from a single +5 V supply and contains an input multiplexer, on-chip track-and-hold amplifier, high speed 12-bit ADC, 2.5 V reference and a high speed serial interface. The AD7890 accepts an analog input range of ±10 V, 0 to 4.096 V or 0 V to +2.5 V depending on the version of the part being used.

This application note explains National Semiconductor’s CHANNEL LINK chipset and discusses related issues in point-to-point subsystem communications. A background on CHANNEL LINK will be offered followed by several high-speed point-to-point applications that build on the basic serial link transmission topology. System issues such as various bus widths, error detection and control line timing are discussed. The concept of a virtual backplane transceiver is also introduced. Finally, design considerations for high-speed serialized links are presented.

Just a handful of components builds an 8-pin microcontroller based circuit for temperature logging via a serial port; small, fast, and acceptably accurate.

This article details the construction of a bench top power supply that can be used to power circuits or devices during development work in the lab. More specifically it is an adjustable, tracking, dual rail supply which means there are two supply voltages, one positive, one negative, that are adjusted by a common potentiometer such that supply voltages are equal in magnitude. It is capable of supplying up to +/- 15V DC at up to 1A. This is sufficient for the majority of small signal electronic projects.

This project will show you how to build Temperature Logger using a Stamp II connected to a PC serial port. I was planing on using the DS1620, but used a LM335 temperature sensor because it only needs a two wire interface and it is easy to waterproof. All i did to waterproof it was to put some heat srink tubing around the 3 wires then around the hole sensor.

The circuit in Figure 1 efficiently monitors common digital-audio signals. One format for such signals is the Audio Engineering Society (AES) 44.1- or 48-kHz standard. Typically, the data consists of a serial data stream with a data rate of approximately 1 Mbps. A lower frequency pulse interspersed in the data stream synchronizes data frames every 16 to 20 data bits.

The hardware is shown in the picture (might take a little while to load). Don't be the least bit concerned if you don't understand everything in the first few paragraphs below. Their purpose is to provide a brief description of the hardware to those who understand the terminology. The terms will be second-nature by the time you finish the tutorial. Just skim the information, make a note of the ordering information and Super Start, then move on to the circuit description below.

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On these pages, I will introduce the Ultrasonic Range Meter with PIC16F873. As for the range meter which doesn't use PIC, refer to "Ultrasonic Range Meter". I created the PCB pattern for this circuit using EAGLE CAD.

An ultrasonic, or sonar, range finder is a common sensor in robotic systems and industrial environments. Even home and automotive uses are possible. A novel sensor design consists of a WC, a few peripheral components, and a pair of ultrasonic transducers (Figure 1). The range-finder module consists of a WC, a transmitter, a receiver, a direct-receive inhibit circuit, and an RS-485 interface. The module's usable range is approximately 4 in. to 16 ft with an accuracy of approximately ±2 in. This performance is sufficient for many industrial, automotive, and robotic uses.

The Universal Flight Controller/Data logger (UFC) is a small light-weight computer designed for multiple applications in the field of advanced model rocketry. This NAR research & development report describes the project from initial conception, through the design and prototyping stages of both the computer hardware and software. In addition, several possible applications and experiments are described and one example is used to gather actual results.

A project required building a synchronous-demodulator circuit to track a line drawn on paper. The beauty of the synchronous-modulator/demodulator approach is its inherent noise rejection. The method rejects nearly all out-of-band noise, whether from internal drift or external illumination. This rejection is a boon in optical tracking, where the return signal is inevitably buried in 120-Hz ambient light, amplifier offsets, and temperature drifts.