This encoder uses a single contact per key keyboard and provides all other switching function electronically. The diode between terminals 8 and 15 prevents the output going more than 1 volt negative with respect to the negative supply V-..
This switch uses four CD4013 BE dual flip-flops, an inverter, and an optoisolator to drive a triac. The circuit can switch 25-A ac load current. A standard 4x3 telephone keyboard is used to enter a 6-digit code. In case of a wrong code, a signal is available to activate ah alarm...
The darkroom timer/controller uses few external components: a display, a digit driver, keyboard, and output switching devices. A 4-digit common-cathode LED display is desirable for dark room environments. The time base is provided by shaping up the 50/60 Hz ac line. A DPDT switch (Si) is used to select a resolution of or 1 seconds and to simultaneously move the decimal point..
The transmitter keyboard is arranged as a scanned matrix. The matrix consists of 7 driver outputs and 7 sense inputs. The driver outputs DRVON to DRV6N are open-drain n-channel transistors and they are conductive in the stand-by mode. The 7 sense inputs (SENON to SEN6N) enable the generation of 56 command codes. With 2 external diodes all 64 commands are addressable.
This encoder uses a single contact per key keyboard and provides all other switching functions electronically. The diode connected between terminals 8 and 15 prevents the output from goitrg more than 1 V negative with respect to the negative supply Vss. The circuit operates overthe supply voltage range from 3.5 V1o 15 Von the device side of the bridge rectifier. Transients as high as 100 V will not cause system failure, although the encoder will not operate correctly.....
Keyboards can be slotted into two categories, at least as far as the manner that the switches are connected is co..
The charger is based on the LTC4053a standalone
timer-terminated constant current/constant voltage linear
charger. The LTC4053 features a thermal loop which
maximizes the charging rate under all conditions by
regulating the maximum die temperature. Less sophisticated
linear chargers must run lower charging rates or
risk overheating, thus increasing charge times...
This application note describes the implementation of an
IBM MF2 compatible keyboard with National Semiconductor`s
COP888CL or COP943C/COP880CL microcontrollers.
Two different solutions have been developed. One solution,
suitable for laptop/notebook keyboards is based on the
COP888CL with special power saving techniques...
In fact a reasonably useful example will be given using a 68HC705J1A single chip microcontroller. We will get it to read the data from the keyboard, convert the scan codes into ASCII and send it out in RS-232 format at 9600 BPS. However we won`t stop here, you will want to see the bi-directional use of the KBD Clock & Data lines, thus we will use the keyboards status LEDS, Num Lock, Caps Lock and Scroll Lock...
The most important criteria of a data-acquisition system for college science laboratories are simplicity and price rather than precision or speed. The data-acquisition system in Figure 1 offers adequate precision of less than 0.5% and speed of 1 Hz to replace the outdated laboratory chart recorder in student laboratories. You can install the system in 5 sec, operate it with a single toggle switch, and construct it for approximately $40. The only additional equipment.....
The i2c-tiny-usb project is an open source/open hardware project. The goal of i2c-tiny-usb is to provide a cheap generic i2c interface to be attached to the usb. It is meant as a replacement for those simple and cheap printer port to i2c adapters. A USB solution has several advantages incl. the built-in power supply and a more future proof interface. Furthermore no cpu intense bitbanging is required on the host side. This USB solution even requires less parts than some.....
This is the Design for a DMX512 to computer keyboard interface. It sits in line on the computer keyboard and on the DMX 512 chain. Decoding The Lighting data and if one it's set channels is set above 1/2 value this unit will output a sequence of keyboard keys to the connected PC. It is primarily designed to be used with PC connected to video projectors, where the lighting controller may require control of a presentation on the video screen but the PC for the presentation.....
The circuit in Figure 1 uses the
MIC2545A-2 and the MIC2778. The MIC2545A-2 is a programmable
current limit high-side switch that is capable of
having current-limit up to 2.5A...
If you're not familiar with the Arduino, it is "an open-source electronics prototyping platform based on flexible, easy-to-use hardware and software". It has a small microcontroller, a USB port to connect to your computer for programming, a power socket for providing power when the USB cable isn't connected, and various digital and analog input and output pins, for connecting up to leds, switches and various sensors.
The Wireless Keylogger consists of two main building blocks: the transmitter, and the receiver. The actual keylogging takes place in the transmitter, which is in fact a PS/2 hardware keylogger, with a built-in 2.4 GHz wireless module. Captured keystroke data is transmitted through the radio-link in real-time, rather than getting stored. The receiver on the other hand, is a wireless acquisition unit with a USB interface. All keystroke data received from the transmitter is.....
The LTC3455 seamlessly manages power flow
between an AC adapter, USB cable and Li-ion battery,
while complying with USB power standards, all from a
4mm ½§ 4mm QFN package. In addtion, two high efficiency
synchronous buck converters generate low voltage rails
which most USB-powered peripherals require...
The SCHAER+ programmer is a programmer for PIC18 family from a PC parallel port (LPT). It is derivated from the SCHAER programmer I used to download my projects in PIC1684. The SCHAER+ programmer should be improved to use a USB connection, without any external power supply... The SCHAER programmer I'm currently using allows me to program chips like PIC16F84 by managing 5 signals through parallel port.
These filters are useful for equalisation, analysis and other tasks such as the Sound to Light converter (Project 62) or even a fully functional Vocoder. For those who have not heard of the vocoder, it is a device that takes a music source as one input and vocals as the other, allowing a guitar, keyboard or complete ensemble to be made to speak or sing. The "speech" from a good vocoder is quite intelligible, and is "ear candy" of the very best kind for experimental musicians...
The core of this construction is 16-Bit Stereo Digital-To-Analog Convertor with USB interface PCM2702. PCM2702 needs only few additional parts to work. The schematic is not complex. Sound card can be powered directly from USB port (jumper W1) or from external power supply (jumper W3). PCM2702 needs two power supply 3.3V (3V-3.6V) and 5V (4.5V-5.5V). I used fixed output voltage LDO TPS76733Q for 3.3V (IO2) and adjustable output voltage LDO TPS76701Q for 5V (IO3). Both LDO.....
A simple logic-analyzer design is compatible with all versions of Windows and pushes the PIC 18C252 chip to its speed limit to achieve a 1-MHz sampling rate (Figure 1). The circuit can examine three channels of relatively low-speed logic signals that have infrequent, or sparse, transitions. The analyzer can record only 510 transitions per run, but a run can last as long as several minutes, if necessary. Applications include monitoring the I/O of an IBM keyboard or printer.....
Transmitters & Receivers
Sensors & Detectors
Low Frequency Amplifiers
Regulated Power Supplies